Food science and hygiene updated by Rajiv Kumar Thakur

2015 Food Hygiene, Sanitation & Safety

Bidhya Koirala

Contents UNIT I: INTRODUCTION ................................................................................................................................. 5 1.1

Define the Food Science and Hygiene .......................................................................................... 5

1.2

Describe the scope of food science and hygiene .......................................................................... 6

UNIT II: MICROORGANISMS AND FOOD ....................................................................................................... 7 2.1

Define bacteria, yeasts and moulds .............................................................................................. 7

2.2

Explain the classification of bacteria yeast and moulds ............................................................... 7

A. Classification of bacteria ............................................................................................................... 7 B. Classification of Yeast ................................................................................................................... 8 C. Classification of Moulds ................................................................................................................ 9 2.3

Describe the factors affecting growth of bacteria, yeasts and moulds ...................................... 10

A. Factors affecting growth of bacteria ........................................................................................... 10 B. Factors affecting growth of molds .............................................................................................. 12 C. Factors affecting growth of Yeasts .............................................................................................. 14 UNIT III: FOOD SPOILAGE ............................................................................................................................ 16 2.2

Discuss the spoilage of foods ...................................................................................................... 16

2.3

Define the term contamination .................................................................................................. 16

2.4

Explain the causes of food spoilage ............................................................................................ 16

2.5

Explain the types of food spoilage .............................................................................................. 18

2.6

Explain the microbial spoilage .................................................................................................... 19

2.7

Explain the non‐microbial spoilage ............................................................................................. 20

2.8

Explain the classification of food on the basis of susceptibility to spoilage ............................... 20

2.9

Explain a way to prevent different types of spoilage ................................................................. 21

UNIT IV: FOOD PRESERVATION ................................................................................................................... 23 4.1

Discuss the principles of food preservation ................................................................................ 23

4.2

Explain the methods of preservation .......................................................................................... 24

4.3

Explain the method drying .......................................................................................................... 25

4.4

Explain high temperature preservation method ........................................................................ 26

4.5

Explain low temperature preservation method ......................................................................... 27

4.6

Explain irradiation ....................................................................................................................... 28

4.7

Explain fermentation and chemicals ........................................................................................... 28

Preservation by Fermentation ............................................................................................................ 28 2

Food Preservation by Chemicals ......................................................................................................... 30 4.8

Explain the traditional methods of food storage ........................................................................ 31

UNIT V: FOOD ADDITIVES ............................................................................................................................ 34 5.1

Define food additives .................................................................................................................. 34

5.2

Explain the classification of food additives ................................................................................. 34

5.3

Explain the applications of food additives .................................................................................. 36

5.4

Potential hazards of food additives ............................................................................................ 38

UNIT 6: FOOD ADULTERATION.................................................................................................................... 39 6.1

Describe food adulteration ......................................................................................................... 39

6.2

Explain common adulteration and their prevention .................................................................. 39

6.3

Discuss food adulteration and public health issue ..................................................................... 41

UNIT 7: FOOD SANITATION AND HYGIENE ................................................................................................. 42 7.1

Discuss the water and its sources of contamination .................................................................. 42

7.2

Discuss treatment of water ......................................................................................................... 42

7.3

Discuss the food and its handling process .................................................................................. 46

7.4

Discuss personal hygiene ............................................................................................................ 47

7.5

Discuss hygiene in the kitchen .................................................................................................... 47

7.6

Explain cleaning & sanitizing, method of washing, rinse ............................................................ 48

UNIT 8: FOOD ACCEPTANCE AND PURCHASING ......................................................................................... 52 8.1

Factors affecting the acceptance of food ................................................................................... 52

8.2

Discuss purchasing of safe foods ................................................................................................ 52

8.3

Discuss receiving of safe foods ................................................................................................... 53

UNIT 9: FOOD AND PUBLIC HEALTH ........................................................................................................... 54 9.1

Discuss food hazards ................................................................................................................... 54

9.2

Explain food borne disease ......................................................................................................... 55

9.3

Discuss symptoms of food poisoning .......................................................................................... 56

9.4

Discuss Natural toxicants in food, toxic metals and chemicals .................................................. 57

9.5

Explain factors associated with food borne illnesses ................................................................. 58

9.6

Explain control and eradication of microorganisms, flies, cockroaches and rodents ................ 59

Control of microorganisms: ................................................................................................................ 59 Control of flies ..................................................................................................................................... 60 Prevention and control of cockroach .................................................................................................. 61 3

Control of rodents ............................................................................................................................... 62 UNIT 10: KITCHEN SAFETY ........................................................................................................................... 64 10.1

Why accidents should be prevented........................................................................................... 64

10.2

Explain how accidents take place ............................................................................................... 64

10.3

Explain the types of accidents ..................................................................................................... 65

10.4

Explain how to prevent cuts ....................................................................................................... 66

10.5

Explain how to prevent burns ..................................................................................................... 67

10.6

Explain how to prevent falls ........................................................................................................ 67

UNIT I: INTRODUCTION 1.1 Define the Food Science and Hygiene The Institute of Food Technologists defines food science as "the discipline in which the engineering, biological, and physical sciences are used to study the nature of foods, the causes of deterioration, the principles underlying food processing, and the improvement of foods for the consuming public".

The textbook Food Science defines food science in simpler terms as "the application of basic sciences and engineering to study the physical, chemical, and biochemical nature of foods and the principles of food processing".

Food science draws from many disciplines such as biology, chemical engineering, and biochemistry in an attempt to better understand food processes and ultimately improve food products for the general public. As the stewards of the field, food scientists study the physical, microbiological, and chemical makeup of food. By applying their findings, they are responsible for developing the safe & nutritious foods.

The basis of the discipline lies in an understanding of the chemistry of food components, such as proteins, carbohydrates, fats and water and the reactions they undergo during processing and storage. A complete understanding of processing and preservation methods is required including drying, freezing, pasteurization, canning, irradiation, extrusion, to name just a few. The ability to carry out analysis of food constituents is developed along with statistical quality control methods. The microbiology and the safety aspects of food must also be understood. Other topics covered include food additives, the physio-chemical properties of food, flavor chemistry, product development, food engineering and packaging. Food science integrates this broad-based knowledge and focuses it on food.

Food hygiene - all conditions and measures necessary to ensure the safety and suitability of food at all stages of the food chain.(WHO) Food can become contaminated at any point during slaughtering or harvesting, processing, storage, distribution, transportation and preparation. Lack of adequate food hygiene can lead to food-borne diseases and death of the consumer. 5

1.2 Describe the scope of food science and hygiene Following are the scope of food science and hygiene i.

Food Services: This can include a number of facilities in the commercial sector like food manufacture, catering services and restaurants where nutrition professionals can do anything from menu planning to meal preparation to quality assurance as well as promotion of the food products.

ii.

Health Care: This is one of the largest and well-known scopes of food science and nutrition in hospitals and clinics. Food scientists/dieticians assist in treating patients with some big hospitals also providing scope for research, food administration, teaching etc.

iii.

Information Dissemination: This entails producing books, articles, promotions, television programmes on optimum food practices, since the present era is highly healthconscious.

iv.

Institutional Catering: Food science professionals are needed to plan and prepare nutritious and well-balanced meals for schools, colleges, factories, offices, canteens etc.

Research & Development: R & D, as it is called, deals with conducting research projects on various food items to ensure welfare from both the commercial food services viewpoint, plus that of the health care provision.

vi.

Social Welfare: Run by governmental organizations, this section is busy in improving the eating habits and consequently, the health of the less-fortunate groups in society

UNIT II: MICROORGANISMS AND FOOD 2.1

Define bacteria, yeasts and moulds Bacteria are single-celled living microorganisms. Varying in length from 1/25,000 to 1/1,000 of an inch, they are among the smallest living creatures known. Moulds: They are multiple cell organisms forming tubular filaments. Molds demonstrate branching and reproduce by means of fruiting bodies, called spores, which are borne in or on aerial structures. Their mycelia, or intertwined filaments, may resemble roots. They are many times larger than bacteria and somewhat longer than yeasts. The most important moulds are; 

Penicillium sp. (Blue moulds),



Aspergillus sp. (Black moulds),



Mucor sp. (Gray moulds), and



Byssochlamys fulva

Yeasts are single-cell, microscopic fungi, usually egg-shaped. They are smaller than molds, but larger than bacteria. Their greatest thickness is about 1/2,000 of an inch. Yeasts reproduce mainly by budding. A small bud forms on the parent yeast cell, gradually enlarges, and then breaks off into another yeast cell. A few varieties reproduce by forming spores within a special cell; later, these spores may form new yeast cells. 2.2

Explain the classification of bacteria yeast and moulds A. Classification of bacteria There are many different ways to classify and group bacteria some of which are as follows: 

Classification on the Basis of Shapes: o Round cells or cocci (varieties include diplococcic, tetrad, streptococci, staphylococci, etc.) o Rod cells or bacilli o Spiral or spirilla o Comma or vibrio o Filamento 7



Classification on the Basis of Gram Strain: This classification is based on the results of Gram Staining Method, in which chemical reagent is used to stain the cell wall of the bacteria. o Gram-positive – e.g: Streptococcus, Staphylococcus, Bacillus, Cornybacterium, Actinomycisis o Gram-negative- e.g: Vibrio, Pseudomonas, Neisseria, Shigella



Classification on the Basis of Oxygen Requirement: This classification is based on the requirement of oxygen for the survival of the bacterium. o Aerobic (Need Oxygen): Staphylococcus, Streptcoccus, Myobacterium, Bacillus, Pseudomonas, etc. o Anaerobic (Do not need Oxygen): Clostridium tetani, Clostridium botulinum, Escherichia coli, Klebsiella, Actinomyces, etc.



Classification on the Basis of Growth and Reproduction: This classification is based on the growth and reproduction aspects of bacteria. o Autotrophic Bacteria (Obtain carob and/or sugar from sunlight or chemical reactions) o Heterotrophic Bacteria (Obtain carob and/or sugar from the environment)

B. Classification of Yeast According to MacMillan and Phaff, there are four groups of yeasts 8



Ascomycetous or true yeast –capable of forming ascospores



Basidiomycetous yeast- having a lie cycle similar to Basidiomycetes (fungi)



Ballistosporogenous yeasts- forcibly discharge spores by the drop excretion mechanism



Asporogrnous yeast or Deuteromycetes or false yeasts- incapable of producing ascospores, ballistospores or sporidia, since sexual lifecycle does not occur or has not been observed so far.

Industrially important yeasts are classified by Reed and Peppler in two classes of fungi based on their spore forming capabilities: 

Ascomycetes or ascosporogenous or true yeasts: e.g. Cryptococcus neoformans



Asexual deuteromycetes or asporogenous or false yeasts: e.g. Candida albicans

C. Classification of Moulds Moulds may be classified into Hazard classes A, B & C: i.

Hazard Class A 

Moulds in this group are either directly hazardous to health due to risk of infection or creation of toxins.



They should not be in homes or workplaces and should be removed right away if found.

ii. Hazard Class B 

Moulds in this group can cause allergic reactions, especially over longer periods of time.

iii. Hazard Class C: 

Moulds in this group aren't known to cause any health risks or reactions in humans.



However, that even moulds in this category can potentially cause structural damage to things that they are growing on, and should still be gotten rid of.

Different types of moulds a) Alternaria: Alternaria is classified in hazard class B and is usually black or grey. It grows on dusty areas such as on walls or around windows and in damp areas such as on plants or in soil.

b) Cladosporium: Cladosporium, is classified in either hazard class B or C, depending on the species. It is usually green, brown, grey, or black and grows in many places, including on walls, dust and insulation. c) Penicillium: Penicillium can be classified in either hazard class B or C, depending on the species. It can be blue, green or white and is often found on food, like cheese and fruit, or in walls and insulation. Thanks to a strain of Penicillium, Penicillin was discovered. d) Stachybotrys Chartarum: Stachybotrys Chartarum, commonly referred to as “black mold”, is classified in hazard class A, meaning it is a toxic mold. Unlike most species of mold, it can only be one colour: black. Black mold can be extremely dangerous and requires a very damp area to grow. e) Acremonium: There are various species of acremonium that can be classified in hazard classes A, B, or C. Acremonium can be found in white, grey, or brown. It is often found on insulation or drywall. f) Ulocladium: Ulocladium can be classified in hazard class B or C. It usually grows in damp areas and is often be found on walls, around windows, and in dusty areas. Ulocladium commonly appears as a grey or black mold. g) Aspergillus: Depending on the species of aspergillus, it can be classified in either hazard class A or B. It can be found in grey, brown, yellow, green, white, or black, and grows on walls, insulation, paper products, soil, and clothing

2.3

Describe the factors affecting growth of bacteria, yeasts and moulds A. Factors affecting growth of bacteria There are six basic factors that affect bacterial growth. One easy way to remember these conditions is to use the easy-to-remember acronym FAT TOM: Food, Acidity, Time, Temperature, Oxygen, and Moisture. i. Food (nutrient requirements): A suitable food supply is the most important condition affecting the growth of bacteria. Every living cell requires certain nutrients to multiply. These include solutions of sugars or other carbohydrates, proteins, and small amounts of other materials such as phosphates, chlorides, and calcium. If the food supply is removed, bacteria will not multiply.

ii. Acidity (pH Requirements): All bacteria have an optimum pH range for growthgenerally around neutral pH- as well as a minimum and maximum. The pH of foods can be adjusted to help control bacterial growth. 

Optimal pH for growth: 6.0 – 8.0



Disease causing bacteria: 4.6 - 9.5



Spoilage bacteria: 1.5 - 9.5

[Note: The term pH refers to the acidity or alkalinity of an aqueous solution. The pH scale ranges from 0 to 14, with pH 7 being neutral. Numbers smaller than 7 indicate a more acidic condition; numbers greater than 7 indicate a more basic, or alkaline, condition.]

iii. Time: Time is a factor in pretty much all of the other five conditions. The more amounts of time bacteria spend in favorable conditions, the higher the rate of reproduction. iv. Temperature: As with pH, all bacteria have an optimum temperature range for growth and a minimum and maximum temperature below or above which they cannot grow. Bacterial groups bear names that indicate their relationships to temperature – psychrophile, psychrotroph, mesophile, and thermophile. 

Psychrophilic (“cold loving”) and Psychrotrophic group. o Both grow above the temperature range of subzero to 20 °C. o Psychrophiles have an optimum temperature of 15 °C and cannot grow above 25 °C. o Psychrotrophs grow best between 25 °C to 40 °C, but can grow slowly in or on food at refrigerator temperatures (around 4 °C). o Both are primarily responsible for the spoilage of refrigerated foods.



Mesophilic group (meso = middle). o Grows best at temperatures of 30 °C to 40 °C). o Some grow well at higher temperatures, such as 46.7 °C.

o All of the bacteria that affect food safety grow within this mesophilic temperature range, although some may be considered psychrotrophic as well. 

Thermophilic group (“heat loving”). o Grow at high temperatures. o Found in soil, manure, compost piles, and even hot springs. o Not pathogenic and do not produce toxins during spoilage of foods; therefore, they do not affect food safety.

v. Oxygen. Bacteria can be placed into groups based on their need for oxygen. 

Aerobes require free oxygen to survive. o Obligate aerobes need a high concentration of oxygen. o Microaerophiles need a lower concentration of oxygen than obligate aerobes.



Anaerobes cannot grow if free oxygen is present. o Obligate anaerobes must avoid all oxygen. o Facultative anaerobes use oxygen when it is present but do not need it to grow. The majority of bacteria are facultative anaerobes.



Aerotolerant bacteria are not affected by oxygen.

vi. Moisture: Bacteria need water to grow. Foods that have a water activity of 0.85 or higher can support the growth of bacteria. Water activity is a measure of how much water is available to the bacteria.

B. Factors affecting growth of molds Following are the major factors affecting growth of mould: i. Food (Nutritional requirements) 

Nutrient requirements for moulds may vary from mould to mould.



Some moulds may thrive well on substrates with high sugar or salt content.



Some may prefer simple sugars while others have the ability to utilize complex sugars.

ii. Temperature 

Different mold species have different optimal growth temperatures, with some able to grow in refrigerators.



The majority of moulds are mesophilic, i.e., they can grow at temperatures within the range of 10-35°C. Optimum temperatures for growth may range between 15 and 30°C.



However, some moulds such as Chaetomium thermophilum and Penicillium dupontii are thermophilic, i.e., they can grow at 45°C or higher and fail to grow below 20°C.



A few moulds are psychrophilic and are unable to grow above 20°C.



A significant number are psychrotolerant and are able to grow both at freezing point and at room temperature.

iii. Light 

Many moulds species grow well in the dark, but some prefer daylight or alternate light and darkness for them to produce spores.

iv. Oxygen



Nearly all molds require oxygen to grow.

v. Acidity (pH Requirements): 

Moulds differ in their pH requirements.



Molds can grow over a pH range of 1.5 to 9.0



Most will grow well over the pH range 3-7.



Some such as Aspergillus niger and Penicillium funiculosum can grow at pH 2 and below.

vi. Moisture (Water activity) 

All moulds require moisture for growth but the amount required varies widely.



Moulds that are capable of growing at very low water activity are referred to as xerophiles, for examples Eurotium species and Wallemia sebi.



Those that are capable of growing at very high water activity are referred to as hydrophilic, e.g. Stachybotrys, Chaetomium and Ulocladium.

C. Factors affecting growth of Yeasts Many environmental factors (e.g temperature, pH, water activity, nutrition etc.) determine the physical and chemical limits for survival and growth of yeasts. i. Temperature 

Most yeasts exhibit optimal growth in the range 20-30 0C, but the upper and lower limits are not well defined for individual species.



Very few species grow above 40-45 0C, but many grow at 2-10 0C, including spoilages species of Saccharomyces and Zygosaccharomyces.



Consequently yeasts can be significant in the spoilage of refrigerated foods. Some species of Candida, Cryptococcus etc grow at temperatures less than 0 0

C and spoil frozen foods.

ii. Acidity (pH Requirements) 

Yeasts grow best in the range pH 4.5-7.0. They prefer acidic environments, and many species grow at pH values as low as 2.0-2.5.



The stronger growth of yeasts at low pH when compared with bacteria leads to their predominance in acid foods.



Very few species grow at pH 9.0 and some species show weak or no growth at pH 7.0-7.5.

iii. Food (Nutritional requirements) 

Yeast can grow in a variety of foods but grow best in foods that contain carbohydrates (sugar and starch) and acid.



They also need nitrogen and several minerals to grow properly. Given these optimum conditions, yeast usually produce carbon dioxide and ethyl alcohol which make them very important to the food industry.

iv. Moisture (Water Activity) 

Most yeast grows best with a plentiful supply of available moisture.



Many yeasts are capable of growing in foods that contain high levels of sugar or salt.



The water requirement of yeast is generally less than bacteria but more than molds

v. Oxygen 

Yeasts grow best in the presence of oxygen (aerobically) but some fermentative yeast can grow slowly without oxygen (anaerobically).

2.4

Explain harmful and useful effects Microorganisms are of significance in food systems because they have both adverse and beneficial effects- they can cause spoilage and illness, but they are also used to produce a variety of foods through fermentation i. Spoilage: Most food undergoes losses in desirability as a result of changes in appearance, texture, odour, and taste during storage. In many foods, these changes are the result of the activity of microorganisms. ii. Foodborne illness: Some microorganisms are capable of illness and are called pathogens. Salmonella, staphylococcus aureus, shigella, clostridium botulinum, and E. coli are some major examples iii. Fermentation: Fermentation occurs when microorganisms grow in food and cause desirable changes. It can occur in both animal foods (e.g. sausage, cheese) and plant foods (e.g. pickles, bread).

Microorganisms

Useful effects

Harmful effects

Bacteria

Certain types of bacteria are

Certain types of pathogenic bacteria

used to make cheese and

causes food poisoning and food

yoghurt

borne illness

Fermentation is used in beer

Ferments food and cause “off”

and wine production as well

flavors in jams

Yeasts

as bread making. 3

Moulds

Certain cheeses have mould

Moulds grow on the outside of food

introduced into them to turn

and affects taste and appearance;

them blue- e.g. stilton

certain types of moulds can be hazardous

UNIT III: FOOD SPOILAGE

2.2

Discuss the spoilage of foods Food spoilage can be defined as decomposition and damage caused to food by various agents making it unsuitable for consumption. Spoilage of food involves any change which renders food unacceptable for human consumption and may result from a variety of causes, which includes 

Insect damage;



Physical injury due to freezing, drying, burning, pressure, drying, radiation etc;



activity of indigenous enzymes in plant and animal tissues;



Chemical changes not induced by microbial or naturally occurring enzymes. These changes usually involved O2, light and other than microbial spoilage, are the most common cause of spoilage e.g. oxidative rancidity of fats and oils and the discoloration of cured meats; and

 2.3

Growth and activity of microorganisms- bacteria, yeasts and molds

Define the term contamination Food contamination refers to the presence of harmful chemicals and microorganisms in food which can cause consumer illness. Contamination is the state of being impure or unfit for use due to the introduction of unwholesome or undesirable elements. Food can be contaminated by insects, rodents, chemicals, microbes, or other foreign particles.

2.4

Explain the causes of food spoilage Food spoils mainly because of any one or more of the following reasons: i. Microbial action: 

Microbes are present everywhere and these organisms can contaminate and spoil food.



Milk turns sour because of microbial action, yeasts ferment fruit juices and mould grows on bread.



Some bacteria which cause food poisoning or food infection may contaminate food which is unhygienically handled.

ii. Presence of contaminants 

If any unwanted inedible matter is added to or is present in food, the food is said to be spoilt.



Contaminants present in food could be nail chipping, hair, stones, grit, dirt or other extraneous matter.



Accidental contamination by metallic fragments (stapler pins, flexible aluminum wires etc) and shards of glass may render food harmful.

iii. Action of insects 

Foods are spoilt because of the presence of worms, weevils, fruit flies, moths, etc.



This may spoil the food and reduce its nutrient content.



The presence of insects or insect body fragments or droppings in food served to customers is highly objectionable and will affect the reputation of the catering establishment.

iv. Natural enzymes 

Foods spoil by autolysis or the action of various enzymes naturally present in them.



Signs of spoilage seen in fruits and vegetables include overmaturing, softening, browning and sprouting.



Enzymes naturally present in meat act on meat fibers and bring about autolysis. If these natural changes are not controlled, food may spoil.

v. Physical changes 

These changes occur in food by freezing, desiccation, evaporation and absorption of moisture.



Mechanical damage during harvesting and transporting foods, like bruising and crushing of fruits and vegetables, broken eggs and cracked shells, can accelerate spoilage by microorganisms because of easy access.

vi. Chemical reactions 

A reaction between acidic food and iron from the can causes hydrogen swell in canned foods



Development of oxidative rancidity in fats and the fatty phases of food results in spoilage of fried snacks and oil based pickles.



Other changes include oxidative discolouration, flavor changes and nutritive loss.

2.5

Explain the types of food spoilage Spoilage of food can broadly be categorized into three major types: i. Physical spoilage 

Physical damage to the protective outer layer of food during harvesting, processing or distribution increases the chance of chemical or microbial spoilage.



Examples of physical spoilage include: o Staling of bakery products and components o Moisture migration between different components o Physical separation of components or ingredients o Moisture loss or gain

ii. Chemical spoilage 

When animal or vegetable material is removed from its natural source of energy and nutrient supply, chemical changes begin to occur which lead to deterioration in its structure.



The two major chemical changes which occur during the processing and storage of foods and lead to a deterioration in sensory quality are lipid oxidation (rancidity) and enzymic browning.



Chemical reactions are also responsible for changes in the colour and flavour of foods during processing and storage.

iii. Microbial spoilage 

These micro organisms (moulds, yeasts and bacteria) do not cause disease but they spoil food by growing in the food and producing substances which alter colour, texture and odour of the food, making it unfit for human consumption.



For example, souring of milk, growth of mould on bread and rotting of fruit and vegetables.

2.6

Explain the microbial spoilage

Most foods serve as good growth medium for many different microorganisms. Considering the variety of foods and the methods used for processing, it is apparent that practically all kinds of microorganisms are potential contaminants. Given a chance to grow, the microorganisms will cause changes in appearance, flavor, odour and other qualities of foods. These degradation processes includes: Putrefaction: Protein foods + proteolytic microorganisms  amino acids + amines + ammonia + H S. 2

Fermentation: Carbohydrate foods + saccharolytic microorganisms  organic acids + alcohol + gases. Rancidity: Fatty foods + lipolytic microorganisms



fatty acids + glycerol.

Microorganisms cause spoilage not only by degradation of foods, but also by synthesis of various products like pigments and polysaccharides leading to discolorations and formation of slimes. The common spoilage defects that occur in different foods with some examples are shown in the table below Food

Types of spoilage

Bread Pickles

Moldy Film/ Pink Yeasts

Fresh Meats

Putrefaction

Alcaligenes, Clostridium, Proteus vulgaris, Pseudomonas fluorescens

Fish

Discolorations

Alcaligenes, Pseudomonas, Flavobacterium

Poultry

Slime, Odor

Alcaligenes, Pseudomonas

Eggs

Colorless & Green Alcaligenes, Rots fluorescens

Concentrated Juices

‘Off’ flavor

Fresh fruits and Soft rots vegetables

Milk/ Cream

Decomposition

Microbes involved Rhizopus nigricans, Penicillium Rhodotorula

Pseudomonas,

Acetobacter, Lactobacillus, Leuconostoc Rhizopus, Erwinia of Yeasts, 19

Proteus,

molds,

Alcaligenes,

Proteus,

2.7

fats

Pseudomonas, Clostridium

Flavor changes

Lactobacillus,Streptococcus, Leuconostoc

Gray & black mold

Botrytis, Aspergillus niger

Micrococcus,

Bacillus,

Explain the non-microbial spoilage

Food may spoil as a result of chemical changes within the food itself or by a reaction between the food and the packaging material. Rancidity is caused by a chemical reaction that breaks down the fatty acids in fat to smaller molecular weight fatty acids and, at the same time, releases certain odiferous products. 2.8

Explain the classification of food on the basis of susceptibility to spoilage Food can be classified into three main groups on the basis of their shelf life or perishability or susceptibility to spoilage. i. Non-perishable or stable foods: 

These foods do not spoil unless they are handled carelessly.



They should be stored in a cool, dry place. They can be stored for more than a year.



They should be picked and cleaned before storage. If necessary, grains can be washed with water to remove any dust and dirt sticking to them. These should be dried in the sun, allowed to cool and stored in containers with tight fitting lids.



Non-perishable foods include sugar, jaggery, hydrogenated fat, vegetable oil, ghee, whole grains, dals, whole nuts, dry salted fish and meat, papads, canned foods, preserves such as pickles, jams, etc.

ii. Semi-perishable foods: 

These foods do not spoil for a fairly long time if stored properly.



They are less likely to decay due to micro-biological contamination then other perishable foods.



Natural chemical breakdown is also slower in such foods. 20



If they are stored in a cool place with adequate ventilation they have moderately long shelf life.



Use of proper containers is equally important.



Semi-perishable foods include processed cereals, pulses and their products like flour, parched rice, popcorn, etc. Their shelf life depends on the storage temperature and moisture in the air.



Other semi-perishable foods are potatoes, onions, canned foods that need refrigeration, apples, citrus fruits, pumpkin, etc.

iii. Perishable foods: 

This is the largest of the three groups and includes most of the food items we consume everyday such as milk products, eggs, poultry, meat, fish, most fruits and vegetables such as bananas, pineapple, papaya, green leafy vegetables, etc.



As these foods contain high amounts of protein, moisture and other nutrients, they are an ideal medium for bacterial growths.



They also spoil easily by natural enzymatic changes.



They have a very short shelf-life of a few hours o few days, after which they spoil rapidly.



It is this group which is responsible for the outbreak of food-borne illnesses.



This group also includes all prepared menu items, opened canned foods and frozen foods which have thawed.



Foods in this group must be stored at low temperatures to retard the action of micro-organisms and enzymes.

2.9

Explain a way to prevent different types of spoilage

A number of methods of prevention can be used that can totally prevent, delay, or otherwise reduce food spoilage.  

Food rotation system: Using the first in first out method (FIFO), ensures that the first item purchased is the first item consumed. Preservatives can expand the shelf life of food and can lengthen the time long enough for it to be harvested, processed, sold, and kept in the consumer's home for a reasonable length of time.



 



Refrigeration can increase the shelf life of certain foods and beverages, though with most items, it does not indefinitely expand it. Freezing can preserve food even longer, though even freezing has limitations. A high-quality vacuum flask (thermos) will keep coffee, soup, and other boiling-hot foods above the danger zone (140F/58C) for over 24 hours. Canning of food can preserve food for a particularly long period of time, whether canned at home or commercially. Canned food is vacuum packed in order to keep oxygen out of the can that is needed to allow bacteria to break it down. Canning does have limitations, and does not preserve the food indefinitely. Lactic acid fermentation also preserves food and prevents spoilage.

UNIT IV: FOOD PRESERVATION

Food is a perishable commodity. The primary objective of food preservation is to prevent or slow down the growth of micro-organisms including moulds, yeasts and bacteria as the growth of these micro-organisms causes spoilage of food. Importance of food preservation i.

ii.

iii.

4.1

To increase the shelf life of food as well as its supply. Although the freshness, palatability and nutritive value may be altered with time delay, perishable foods can be preserved to prevent spoilage and made to be available throughout the year. In this way, preservation helps to increase variety in our diet and makes it better balanced. To save food for future use at the time of scarcity or drought etc. after suitable preservation and proper storage. Preservation of food also minimizes the preparation time and energy at home. To stabilize the price of food throughout the year since seasonal food can be preserved and made available for consumption throughout the year. Discuss the principles of food preservation There are three major principles of food preservation: i. Prevention or delay of the growth of microorganisms. ii. Prevention or delay of self-decomposition iii. Prevention of damage from insects or animals . i. Prevention or delay of the growth of micro-organisms 

Avoiding invasion of micro-organisms e.g. by aseptic techniques



Removing micro-organisms e.g. filtration



Inhibiting the growth and activity of micro-organisms e.g. freezing, refrigeration, drying, anaerobic conditions, chemicals or antibiotics



Killing the micro-organisms e.g. heat or irradiation

ii. Prevention or delay of self-decomposition 

Destruction or inactivation of inherent enzymes naturally existing in food e.g. by blanching



Prevention or delay of chemical reactions e.g. prevention of oxidation by using antioxidants 23

iii. Prevention of damage from insects or animals 

By using suitable chemicals to kill insects or animals from destroying the foods.



By storing foods in dry, air tight containers to prevent the insects or animals from destroying them.

4.2

Explain the methods of preservation Based on the mode of action, the major food preservation techniques can be categorized as i. Slowing down or inhibiting chemical deterioration and microbial growth, ii. Directly inactivating bacteria, yeasts, molds, or enzymes, and iii. Avoiding recontamination before and after processing A number of techniques or methods from the above categories are shown in figure below

4.3

Explain the method drying The technique of drying is probably the oldest method of food preservation practiced by mankind. The preservation of foods by drying is based on the fact that microorganisms and enzymes need water to be active. In preserving foods by this method, one seeks to lower the moisture content to a point where the activities of food spoilage and food-poisoning microbes are inhibited. Dried, desiccated foods are those that generally do not contain more than 25% moisture. Drying techniques Several types of dryers and drying methods are commercially used to remove moisture from a wide variety of food products including fruit and vegetables. There are three basic types of drying process: i.

Sun drying and solar drying 

The earliest uses of food drying/ desiccation consisted of exposing fresh foods to sunlight until drying had been achieved.



Fruits such as grapes, apricots may be dried by this method, which requires a large amount of space for large quantities of product.

ii. Atmospheric drying including batch (kiln, tower and cabinet dryers) and continuous

(tunnel, belt, belt-trough, fluidized bed, explosion puff, foam-mat, spray, drum and microwave) 

Eggs may be dried as whole egg powder, yolks, or egg white. Dehydration stability is increased by reducing the glucose content prior to drying. Spray drying is the method most commonly employed.



Milk is dried as either whole milk or nonfat skim milk. The dehydration may be accomplished by either the drum or spray method.



Meat is usually cooked before being dehydrated. The final moisture content after drying should be approximately 4% for beef and pork.

iii. Sub-atmospheric dehydration (vacuum shelf/belt/drum and freeze dryers).



In freeze drying (lyophilization, cryophilization), actual freezing is preceded by the blanching of vegetables and the precooking of meats. Freeze drying is generally to high temperature vacuum drying. 25

4.4

Explain high temperature preservation method The use of high temperatures to preserve food is based on their destructive effects on microorganisms. With respective to food preservation, there are two temperature categories in common use: o Pasteurization o Sterilization i. Pasteurization  Pasteurization by use of heat implies either the destruction of all disease producing organisms (e.g. pasteurization of milk) or destruction or reduction in the number of spoilage organisms in certain foods, as in the pasteurization of vinegar.  It is a process of heating a food, usually liquid, to a specific temperature (below boiling point) for a definite length of time, and then cooling it immediately. This process slows microbial growth in food.  Pasteurization aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and consumed before its expiration date).  The process of pasteurization was named after Louis Pasteur who discovered that spoilage organisms could be inactivated in wine by applying heat at temperatures below its boiling point. The process was later applied to milk and remains the most important operation in the processing of milk.  There are basically two methods of pasteurization in use today:  Batch: In the batch process (batch pasteurizer), a large quantity of milk is held in a heated vat at 65°C for 30 minutes, followed by quick cooling to about 4°C.  Continuous flow: In the continuous flow process (continuous flow pasteurizer,)-also known as HTST, for high temperature, short time, milk is forced between metal plates or through pipes heated on the outside by hot water. While flowing under pressure, the milk is held at 72°C for at least 16 seconds. Before being chilled back to 4°C or cooler, it flows through a heat exchanger to pre-warm cold milk just entering the system. ii.

Sterilization  The heat sterilization involves exposing food to a temperature generally exceeding 100◦C for a period sufficient to inhibit enzymes and all forms of microorganisms including bacteria spore.  This method can be used commonly to sterilize foods in cans or containers. Canned foods are sometimes called commercially sterile.



 

Most of the ready to serve beverages, nectars and fruit juices are preserved in bottles after sterilization. The liquid materials are heated up to their boiling point (beyond 100 0C along with all additives, viz, colours, flavours, etc.) and are filled into pre-sterilized bottles. Later the bottles are crown corked. Canning is also a heat sterilization process for preserving food materials like fruits, vegetables, meat, fish, etc. Except for the consumption of large quantities of heat and can metal (usually tin metal is used), canning is also an excellent process of food preservation. Sterilization is a term referring to any process that eliminates (removes) or kills all forms of microbial life, including transmissible agents (such as fungi, bacteria, viruses, spore forms, etc.) present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media.

4.5

Explain low temperature preservation method The commonly applied low temperature preservation (cooling) methods are refrigeration, freezing, freeze drying, etc. Some of them are explained below i.

Refrigeration: - Refrigeration is normally resorted to storing food materials for a limited period which varies from 2-10 days. - The refrigeration temperatures are usually of the order of 0 0C to 5 0C. - Food materials, whether solids or liquids or pastes or doughs, can be stored either with some amount of preprocessing or in the raw form. - Refrigerated preservation is generally used for retail vending of processes/unprocessed foods. - Frozen foods are stored at -18 0C until they are transported to retail selling.

ii.

Freezing - Freezing is an excellent process of preservation of food materials without virtually losing any nutrients. - The texture of the food materials is also not lost during freezing. - The food materials are initially preprocessed to remove most of the unwanted materials and frozen at -18 0C to -25 0C, later they are stored at -18 0C temperature until they are transported for retail vending. - Ice-cream, fruit pulps, processed meat are preserved by freezing alone as it is not amenable to canning. - Except for consumption of high energy for freezing, it is an excellent method for food preservation.

4.6

Explain irradiation  Food irradiation is a preservation process of exposing foods to high-energy rays to improve product safety and shelf life.  Food irradiation is a technology for controlling spoilage and eliminating food-borne pathogens, such as salmonella. The result is similar to conventional pasteurization and is often called "cold pasteurization" or "irradiation pasteurization."  Like pasteurization, irradiation kills bacteria and other pathogens that could otherwise result in spoilage or food poisoning.  Red meats, poultry, potatoes, onions, spices, seasonings, fresh fruits and vegetables may be irradiated to prevent growth of food poisoning bacteria, eliminate parasites, or delay ripening and spoilage. Also, irradiation could be used to replace chemical preservatives in foods.  There are three main sources of radiation approved for use on foods.  Gamma rays are emitted from radioactive forms of the element cobalt (Cobalt 60) or of the element cesium (Cesium 137).  X-rays are produced by reflecting a high-energy stream of electrons off a target substance (usually one of the heavy metals) into food.  Electron beam (or e-beam) is similar to X-rays and is a stream of high-energy electrons propelled from an electron accelerator into food.

4.7

Explain fermentation and chemicals

Preservation by Fermentation Fermentation could be described as a process in which microorganisms change the sensory (flavor, odor, etc.) and functional properties of a food to produce an end product that is desirable to the consumer. Technically, fermentation is the biochemical conversion of sugars, starches, or carbohydrates, into alcohol, and organic acids, by bacteria and enzymes.

Fermentation as a Preservation Method As new preservation techniques have been developed, the importance of fermentation processes for food preservation has declined. Yet fermentation can be effective at extending the shelf life of foods and can often be carried out with relatively inexpensive, basic equipment. Therefore, it remains a very appropriate method for use in developing countries and rural communities with limited facilities

To reduce or prevent microbial spoilage of food, fermentations use a combination of the following three principles. 

Minimize the level of microbial contamination onto the food, particularly from “high-risk” sources (asepsis)



Inhibit the growth of the contaminating micro flora



Kill the contaminating microorganisms

Fermentation improves the safety of foods by decreasing the risks of pathogens and toxins achieving the infective or toxigenic level, and extends the shelf life by inhibiting the growth of spoilage agents, which cause the sensory changes that make the food unacceptable to the consumer. Additional Benefits of Fermentation 

Fermenting enhances the flavors of some foods, as with the extended fermentation of wine, and beer, which creates their distinctive flavors.



Fermenting makes foods more edible by changing chemical compounds, or predigesting, the foods for us. There are extreme examples of poisonous plants like cassava that are converted to edible products by fermenting.



Fermentation increases nutritional values with the biochemical exchange it produces, and allows us to live healthier lives. Here are a few examples: 

The sprouting of grains, seeds, and nuts, multiplies the amino acid, vitamin, and mineral content and antioxidant qualities of the starting product.



Fermented beans are easier for our bodies to digest, like the proteins found in soy beans that are nearly indigestible until fermented.



Fermented dairy products, like, cheese, yogurt, and kifir, can be consumed by those not able to digest the raw milk, and aid the digestion and well-being for those with lactose intolerance and autism.



Vinegar is used to leach out certain flavors and compounds from plant materials to make healthy and tasty additions to our meals.

Principal groups of microorganisms used in food fermentation 1. Lactic acid bacteria (LAB)- Lactobacillus, Lactococcus, Streptococcus 29

2. Acetic Acid Bacteria – Acetobacter, Gluconobacter 3. Yeasts – converts food to alcohol and carbondioxide 4. Molds- converts food to enzymes

Examples of more common fermented foods SN

Food

Principal Ingredient

Microorganism

Wine

Grapes

Yeasts

Beer

Barley

Yeasts

Bread

Wheat

Yeasts

Yoghurt

Milk

Lactic Acid Bacterial (LAB )

Cheese

Milk

Lactic Acid Bacteria (LAB)

Soy Sauce

Soybeans

Molds+ LAB+ Yeasts

Fermented Sausages

Meat

LAB+ molds

Food Preservation by Chemicals Chemical preservation of food is done by use of chemicals commonly known as food preservatives. Preservatives are substances which, under certain conditions, either delay the growth of microorganisms without necessarily destroying them or prevent deterioration of quality during manufacture and distribution. The purpose of using a chemical agent as a preservative is to retard food spoilage caused by microorganisms Preservatives can be naturally occurring or synthetic substance that is added to food products to prevent decomposition by microbial growth or by undesirable chemical changes. These substances are added in very low quantities (up to 0.2%) which do not alter the physiochemical properties of the foods at or only very little. Roles of chemical preservatives in food preservation 

Chemical preservatives interfere with the cell membranes of microorganisms, their enzyme activity or then genetic mechanisms.



Preservatives may also serve as antioxidants, stabilizers, firming agents as well as moisture retainers.

Commonly used preservatives in food preservation: Different chemical preservatives are used, which involves i.

ii.

Traditional chemical food preservatives 

Sugar



Salt

Acidulants 

Benzoic acid



Sorbic acid



Lactic acid

iii. Gaseous chemical food preservatives/ leavening agents 

Sulphur dioxide and sulphites



Carbondioxide

iv. Antioxidants

4.8



Butylated Hydroxy Anisole (BHA)



Butylated Hydroxy Toluene(BHT)



Propyl Gallate



Natural/Synthetic Tocopherols (Vitamin E)



Ascorbic Acid (vitamin C) and



Lecithin.

Explain the traditional methods of food storage The traditional methods were mostly based on reducing the moisture or activity of water so that the food spoiling microorganisms could not survive. This would obviously cause some changes or damage to the physical structure of the foods viz. contraction in volume and surface area and hence contraction in cellular structure, etc. Some of the commonly used traditional methods are: i.

Dehydration by Sun Drying 

This method is indeed considered as the grandmother’s technique of preserving foods.



The food on dehydration loses moisture and thus, water is not available for microorganisms to grow and survive.



The food item also loses weight, and hence is easy to handle and transport.



In the olden days, the food materials, may be it grains, pulses, meat, fish or vegetables, were kept in yards under sunshine to get dried.

 ii.

It was an excellent method in terms of energy saving and convenience.

Salting 

Salt (Sodium Chloride) is used as a preservative in food processing.



It also works on the principle that it does not allow moisture to be available for microorganisms for their survival and growth.



In fact, salt is considered as a number one natural preservative. There is no limit for its addition except for taste.



A combination of both salting and drying is also used for preservation of fish, meat and some vegetables.

iii.

Pickling 

The effect of pickling is also akin to salting, which reduces the water activity.



Pickling is done both by acids and by oil.



The food materials like fish, meat, prawns, some vegetables, etc are initially dried (or cooked in case of some animal based products) and later the dry material is pickled in acids (like acetic acid-vinegar) or in vegetable oils.



Some of the Nepali pickles made out of fruits/vegetables have a shelf life of one year or more.

iv.

Smoking 

Smoking is one of the oldest food storage methods along with drying, when food was cooked over open fires.



Smoked meats traditionally were sliced thin and placed over a fire where three modes of preservation took place: The heat of the fire killed harmful

microorganisms, some of the chemical compounds in the wood being used for smoking had anti-microbial actions, and dehydration prevented degradation.

UNIT V: FOOD ADDITIVES 5.1

Define food additives Food additives are substances which are added to food which either improve the flavor, texture, colour or chemical preservatives, taste, appearance or function as processing aid. Food additives as non-nutritive substances added intentionally to food, generally in small quantities, to improve its appearance, flavor, texture or storage properties. According to Joint FAO/WHO Codex Alimentarius Commission (1991) Food additive means any substance not normally consumed as a food by itself and not normally used as a typical ingredient of the food, whether or not it has nutritive value, the intentional addition of which to food for a technological (including organoleptic) purpose in the manufacture, processing, preparation, treatment, packing, packaging, transport or holding of such food results, or may be reasonably expected to result (directly or indirectly), in it or its by-products becoming a component of or otherwise affecting the characteristics of such foods. The term does not include “contaminants” or substances added to food for maintaining or improving nutritional qualities.

Food additives must serve one of the following purposes: 

Preserving nutritional quality of the food;



Providing necessary ingredients or constituents of foods manufactured for group of consumers with special dietary needs.



Enhancing the keeping quality or stability of a food;



Improving the organoleptic properties provided that the nature, substance or quality of the food is not changed in such a way as to mislead the consumer.

5.2

Explain the classification of food additives The classification of food additives as per Codex Alimentarius SN Functional classes

Definition

Acidity Regulator

A food additive, which controls the acidity or alkalinity of a food.

Anti Caking Agent

A food additive, which reduces the tendency of particles of food to adhere to one another

Antifoaming agent

A food additive, which prevents or reduces foaming.

Antioxidant

A food additive, which prolongs the shelf-life of foods by protecting against deterioration caused by oxidation such as fat rancidity and color changes

Bleaching agent

A food additive (non-flour use) used to decolourize food. Bleaching agents do not include pigments.

Bulking agent

A substance, other than air or water, which contributes to the bulk of a food without contributing significantly to its available energy value

Carbonating agent

A food additive used to provide carbonation in a food.

Color

A food additive, which adds or restores color in a food

Color

retention A food additive, which stabilizes, retains or intensifies the color of a food

agent 10

Emulsifier

Forms or maintains a uniform mixture of two or more phases in a food

Emulsifying salt

Rearranges cheese proteins in the manufacture of processed cheese, in order to prevent fat separation

Firming agent

Makes or keeps tissues of fruit or vegetables firm and crisp, or interacts with gelling agents to produce or strengthen a gel

Flavour enhancer

Flour

Enhances the existing taste and/or odour of a food

treatment A substance added to the flour to improve its baking quality or

agent

colour

Foaming agent

Makes it possible to form or maintain a uniform dispersion of a gaseous phase in a liquid or solid food

Gelling agent

Gives a food texture through formation of a gel

Glazing agent

A substance which, when applied to the external surface of a food, imparts a shiny appearance or provides a protective coating

Humectant

Preservative

A food additive, which prevents food from drying out by counteracting the effect of a dry atmosphere. Prolongs the shelf-life of a food by protecting against deterioration caused by microorganisms

Propellant

A gas, other than air, which expels a good from a container

Raising agent

A substance or combination of substances which liberates gas and thereby increases the volume of a dough

Stabilizer

Makes it possible to maintain a uniform dispersion of two or more substances

5.3

Sweetener

A non-sugar substance which imparts a sweet taste to a food

Thickener

Increases the viscosity of a food

Explain the applications of food additives The applications of some major group of food additives are as follows: i. Antioxidants  Antioxidants like lecithin, ascorbic acid, tocopherol. Butylated hydroxyanisole (BHA) can be added to ghee, butter, etc to prevent its oxidative deterioration. ii. Preservatives

  

Class I preservatives can be used without restriction e.g. salt, sugar, spices, vinegar. Class II preservative use is restricted to only certain foods. The presence of a Class II preservative has to be declared on the packaging/ label e.g. sulphites, nitrates and nitrites, benzoic acid, sorbic acid.

iii. Food colours



Use of colour is restricted to only specific items of food. Caramel can be used without label declaration- other natural colours must be declared e.g. beta carotene, chlorophyll, riboflavin, annatto,saffron, curcumin or turmeric. Some common permitted synthetic food colors for use include: Ponceau 4R, Carmoisine, Erythrosine (red); Tartrazine, Sunset Yellow FCF (Yellow); Indigo Carmine, Brilliant Blue FCF (blue); Fast Green FCF (Green). Synthetic food colours are permitted only in certain foods such as ice cream, biscuits, cakes, canned peas, fruit squashes.

iv. Flavouing agents



There are over 1200 different flavoring agents used in foods to create flavor or replenish flavors lost or diminished in processing, and hundreds of chemicals may be used to simulate nature flavors. Alcohols, esters, aldehydes, ketones, protein hydrolysates and MSG are examples of flavoring agents. Natural flavoring substances are extracted from plants, herbs and spices, animals, or microbial fermentations. They also include essential oils herbs, spices and sweetners. 36



Synthetic flavoring agents are chemically similar to natural flavorings, and offer increased consistency in use and availability. They may be less expensive and more readily available than the natural counterpart although they may not adequately simulate the natural flavor. Some examples of synthetic flavoring agents include amyl acetate, used as banana flavoring benzaldehyde, used to create cherry or almond flavor, ethyl butyrate for pineapple, methyl anthranilate for grape,etc. Flavor enhancers such as monosodium glutamate (MSG) is permitted in restricted amounts and its addition needs to be declared on the label with a warning that the food is un-suitable for children below 12 months of age.

Emulsifying and stabilizing agents  Commonly used emulsifying / or stabilizing agent include agar, alginates, dextrin, sorbitol, pectin, cellulose, mono glycerides or diglycerides of fatty acids.  Modified starches are being used the world over by the food processing industry as thickeners, binders and stabilizers. These starches make sauces thick, potato chips crisp, pudding smooth in texture.  Edible gums are used as thickening agent in jams, gravies and sauces: jellying agent in pudding desserts: encapsulating agent to stabilize flavours.

vi. Anti- caking agents



Anti- caking agents are anhydrous substances that can pick up moisture without themselves becoming wet and these are added to products such as table salt and dry mixes. “Free flowing” salt has anticaking agents added to prevent formation of lumps. Common permitted anticaking agents include carbonates of calcium, magnesium; silicates, myristates, palmitates or stearates. In addition, calcium, potassium or sodium ferrocyanide may also be used as anticaking agents in common salt, iodized salt and iron-fortified salt.

vii. Buffering agents



Buffering agents are materials used to counter acidic and alkaline changes during storage or processing of food, thus improving flavour and increasing stability of foods. Examples are acetic acid, calcium oxide, ammonium phosphate monobasic, ammonium carbonate (bread improver in flour), citric acid, malic acid, DL lactic acid, L (+) tartaric acid (acidulants).

5.4

Potential hazards of food additives Some of the potential hazards of food additives are categorized in the table below:

Additives Preservatives

Flavoring Agents

Sweeteners

Colors

Emulsyfying and  Carrageenan has been correlated to inflammation and been stabilizing agents shown to cause ulcers, colon inflammation, and digestive cancers. Firming agent  Citric agent In large or concentrated amounts can cause tooth erosion

Potential Hazards  Butylated Hydroxyanisole or BHA is considered to have a carcinogenic effect.  Researches suggest that adding nitrites to food as a preservative can actually encourage the formation of chemicals that cause cancer within that food.  Food preservatives can weaken heart tissues.  Aspartame, sulfites, benzoates and yellow dye No. 5 as preservatives can exacerbate breathing problems in asthmatics and others  MSG promotes the growth, and spread, of cancer cells within the body, and can also be linked to "sudden cardiac death.  MSG is also linked with obesity and inflammation within the body, particularly the liver.  use of artificial sweeteners over a longer period is believed to encourage the development of urinary tract tumors  Aspartame can cause neurological problems, such as hallucinations, and that consumption of the artificial sweetener, over extended periods of time, increases cancer risks.  It is suspected that cyclamate may actually increase the cancer-causing activity of other substances, rather than causing cancer itself.  Saccharin has been found to cause cancer of the ovaries, as well as other organs, and increases the cancer-causing effects of other compounds.  Mannitol (sugar alcohols) are not fully digestible and they can cause intestinal discomfort, gas, bloating, flatulence, and diarrhea.  Synthetic colors like brilliant blue and indigotine have been loosely linked to cancers in animal studies.  Colors may also cause hypersensitivity (allergy-like) reactions in some consumers and might trigger hyperactivity in children.

UNIT 6: FOOD ADULTERATION 6.1

Describe food adulteration According to the Food Act of Nepal, 2023 (1997), "adulterated food" means any food in any of the following conditions:  The food which is so rotten, decayed or kept or prepared in a dirty or filthy or poisonous condition that it is injurious to health,  The food of which some or all parts have been so made of any diseased or disease carrying animal, bird or injurious vegetation as to render it unfit for consumption by the human being,  The food which is likely to be injurious to health because of the fact that any food additive, preservative, inner or outer mixed chemical compound or pesticide level exceeds the prescribed upper limit. A food adulterant may be defined as any material which is added to food or any substance which adversely affects the nature, substance and quality of the food. Food adulteration takes into account not only the intentional addition or substitution or abstraction of substances which adversely affect the nature, substances and quality of foods, but also their incidental contamination during the period of growth, harvesting, storage, processing, transport and distribution. Simple example of food adulteration includes addition of water to milk; removal of fat from milk, etc. Reasons/Causes of food adulteration  Vested interests of individuals for profit making, ignoring public health and safety.  May be due to ignorance by individuals (lack of knowledge & regulatory provisions, accidental causes)  In addition to individuals adding adulterants to products, companies may try to extend their profit making by extending their products.

6.2

Explain common adulteration and their prevention The following table gives a compilation of common adulteration in food items SN Food Items Common adulterants 1 Milk Water, Antibiotic residues, formalin, boric acid, pesticide residues, urea, sugar, starch. 2 Chilli powder Brick dust, saw dust 3 Turmeric powder Yellow aniline dyes, Tapioca starch, non-permitted colors like metanil yellow 39

4 5 6

7 8 9 10 11 12 13

Ghee and Vanaspati

Extraneous color, animal body fat, hydrogenated vegetable oil, excessive moisture Edible oils Mineral oils, argemone oil, aflatoxin, pesticide residues, cheaper vegetable oils Spices Non-permitted colors, mineral oil coating, husk starchm foreign seeds, exhausted spices, extraneous matter Non alcoholic beverages Saccharin, non-permitted colors and excessive permitted colors Confectionary, sweets Non-permitted colors, aluminium foil, permitted colour more than prescribed limit Coffee Chicory powder, date or tamarind seeds,artificial color Tea Iron filings, foreign leaves, exhausted leaves Pulses and their products Foreign pulses like khesari, foreign starch, extraneous like besan matter Cereals and their products Fungal infestation, pesticide residues, sand, dirt,marble like atta, maida, suji chips, foreign starch, powdered chalk, iron filings Black pepper Papaya seeds

Prevention measures ii.

Detection/ testing/checking before purchase  During purchases, if any food items are suspected of adulteration they can be detected by consumers using a variety of simple techniques.  Adulteration of papaya seed with Black Pepper may be detected by way of visual examination as also by way of smelling. Papaya seeds do not have any smell and are relatively smaller in size.  These adulterants like sand, grit, etc in rice and other cereals may be detected visually and removed by way of sorting, picking, and washing.

iii.

Consumer awareness  Consumer awareness and sensitization can be an important way to prevent adulteration. Consumers can be made aware of their rights and dangers of consuming adulterated food.  Further, awareness campaigns can be conducted to educate the consumers to get samples of suspected items tested at recognized laboratories for further action or to make complaints if they are of any adulteration in their surroundings.

iv.

Regulatory measures

  v.

6.3

Any person/ entity responsible for adulteration may be liable to penalties and punishments as specified in the food act and regulations. The existing laws should be made fool proof and be implemented mercilessly.

Food inspections and monitoring  The authorities, especially food technology and quality control department should take severe action against those who are adulterating food.  Surprise raids and frequent checks should be conducted. Food inspectors should visit hotels and consumer stores to find the wrongdoers who are misusing the license given to them. Discuss food adulteration and public health issue There are many adulterants which might prove to be a hazard to our health especially if consumed over a long period of time. Following are some of the impacts of adulterants on public health:  Mustard oil is often adulterated with oil of prickly poppy (Argemone Mexicana)/ This argemone oil has toxins that can cause epidemic dropsy. Some of the symptoms of epidemic dropsy are swelling of the body, acute nausea, vomiting and loose motions.  Many adulterants are carcinogenic. For example metanil yellow and malachite green are textile dyes which are used immorally as food coloring agents. Accordingly, they constitute a serious public health hazard and are sufficient environmental concern. They both have carcinogenic effects.  Khesari dal is often used a scommon adulterant of Bengal gram dal. Khesari dal contains neurotoxins that cause lathyrism which is a kind of paralysis.  Lead chromate powder used in turmeric causes brain damage and stiffness of limbs.  Auramine which is a food color affects the liver and kidney.  Tamarind and date seed powder mixed with coffee powder can cause diarrhea.  Adulteration on bakery items and dairy products may have tremendous effects on a child’s health. Such as cream-filled foods, cereal, cream sauces causes increased salivation, abdominal cramp, vomiting, prostration etc.  Chalk-powder mixed in sugar may cause stomach disorder.

UNIT 7: FOOD SANITATION AND HYGIENE 7.1

Discuss the water and its sources of contamination Pure Water: Pure water may be defined as water that is free of extraneous substances. Safe Water: Safe water is water that is not likely to cause undesirable or adverse effects although it may contain various contaminants. Safe means that although the purified water may contain some contaminants, the risks imposed by those contaminants are of an acceptable nature.

7.2

Discuss treatment of water Contaminated/ impure water can be treated/ purified by either of the following methods i. Natural Method:  impounding or storage  oxidation and settlement ii. Artificial method  Physical: distillation, boiling  Chemical: precipitation, disinfection or sterilization  Filtration: slow sand filtration, rapid sand filtration, domestic filtration Water can be treated at two levels: large scale treatment and small-scale treatment. i. Large scale treatment/purification of water a. Storage and sedimentation: Water is impounded/stored in artificial or natural reservoirs  Ninety percent of suspended impurities settle down in 24 hours thus making the water clearer.  The amount of free ammonia is reduced and that of nitrated increases because aerobic bacteria oxidize the organic matter.  There is approximately 90% reduction in bacterial count in the first five to seven days. Optimum period is 10-14 days. If water is stored for longer duration there is chance of algal growth giving rise to foul smell and color change of water.  Rate of sedimentation may be enhanced by the use of alum (Phitkiriammonium sulphate). b. Coagulation and filtration: This is done through sand filter beds: > 98-99 percent bacteria and other impurities are removed. Sand filters are of two types: Slow sand or biological filters and repid sand or mechanical filters

Slow sand or biological filters:  Filter beds are watertight rectangular tanks or reservoirs ordinarily kept open. They are 2.7 to 3.6 m deep and have a constant head of water above the sand bed.  The sand bed has two layers of bricks placed one over the other on their edges and arranged in the form of drains for the passage of filtered water.  The next layer consists of gravel, broken stones or pebbles 15-30 cm high, followed by a 15-30 cm layer of coarse sand.  Above this a 90 cm layer of fine sand and a waterhead of 90 cm from the settling tank.  The action of the slow sand filter is three fold. o Mechanical straining of suspended impurities by the upper layer of filter o Chemical action as organic matter is oxidized by presence of air and nitrifying micro-organisms in the sand. o Biological action in the vital layer: The vital layer is formed after a few days of use of the filter. It is a slimy gelatinous layer consisting of algae, plankton and bacteria which remove organic matter; oxidize ammoniacal nitrogen to nitrates and help in yielding bacteria-free water. As this layer retains all the bacterial of the water, it should not be disturbed.  Percolation takes two hours or more and for efficient filtration, the rate of flow should not exceed 0.1 to 0.4 m3/hr/m2 surface area.  By this filtration, total bacterial count is reduced by 99.9 to 99.99 % and E. coli is reduced to 99 to 99.9%.

Slow Sand Filter

Rapid Sand or Mechanical Filters:  The filters are small and fixed inside a covered shed. The wooden, iron or concrete cylinders are 2m deep and have a 1.2 to 1.5 m thick filtering media.  They filter water at a very high rate. The steps involved are: o Coagulation: raw water is treated with a chemical coagulant, for example, alum. o Rapid mixing: this allows quick and thorough mixing and distribution of alum throughout water o Flocculation: this is a slow and gentle stirring for 30 mins which results in a flocculant precipitate of aluminuim hydroxide. o Sedimentation: water is kept for two to six hours to allow the floculant precipitate impurities and bacteria to settle down. At least 95% of the bacteria need to be removed before the water enters the rapid sand filters. o Filtration: the size of sand grains is between 0.6-2 mm. Rate of filtration is 515 m3/ hr/m2 area. The alum flocculant, which is held back, forms a slimy layer which absorbs bacteria and also causes oxidation of ammonia. The suspended impurities may clog the filters which are then subjected to a washing process called back washing, i.e. reversing the water flow. o By this filtration. 98-99 percent bacteria are removed.

Steps in rapid sand filtration

Chlorination: In water treatment or purification practice, the term disinfection is synonymous with chlorination. Disinfection of water is therefore, usually carried out by the use of chlorine who fulfils all the criteria’s of good disinfectant. This supplements sand filtration. Chlorine kills pathogenic bacteria but has no effect on spores and certain viruses except in high doses. It also oxidizes iron, manganese and hydrogen sulphide, 44

helps in coagulation, controls the growth of slime producing organisms and algae and it destroys constituents which contribute to odour and taste. The recommended concentration of chlorine is 0. 5 mg/L for one hour. A minimum level of 0.2 ppm to 0.5 ppm residual chlorine is recommended for drinking water. ii. Small scale treatment/purification of water a. Boiling: It is highly efficacious method, killing human pathogens even in turbid water and at high altitude Water must be boiled vigorously for five to ten minutes. This kills all spores, cysts and ovas and yields relatively sterilized water. It also removes temporary hardness of water. b. Chemical disinfection: Chemical disinfection of water can be done by following disinfectants:  Bleaching powder: contains 33 percent available chlorine when fresh. It is unstable but retains its strength when mixed with excess of lime.  Five percent solution of chlorine.  Perchloron or HTH (High Test Hypochlorite)  Chlorine tablets: one tablet of 0.5 gm is sufficient to disinfect 20 litres of water.  Iodine: two drops of 2% ethanol solution of iodine is sufficient for on elitre water. A contact period of 20-30 minutes is required.  Potassium permanganate: It kills the cholera vibrio but is not effective against other organisms. It changes color, smell and taste of water. c. Filtration: Water is filtered through ceramic filters that consist of a candle that holds back bacteria but not viruses. The candle may be made of unglazed porcelain or coated with a sliver catalyst. The candles needs to be cleaned by scrubbing with a brush under running water and should be boiled at least once a week. Pores may increase in size after repeated use and brushing and make the filter ineffective. d. Solar Disinfection (SODIS):  Solar Water Disinfection (SODIS) is a simple, environmentally sustainable, low-cost solution for drinking water treatment at household level for people consuming microbiologically contaminated raw water.  SODIS uses solar energy to destroy pathogenic microorganisms causing water borne diseases and therewith it improves the quality of drinking water.  Pathogenic microorganisms are vulnerable to two effects of the sunlight: radiation in the spectrum of UV-A light (wavelength 320-400nm) and heat (increased water temperature).



7.3

Contaminated water is filled into transparent plastic bottles and exposed to full sunlight for six hours. During the exposure to the sun the pathogens are destroyed. If cloudiness is greater than 50%, the plastic bottles need to be exposed for 2 consecutive days in order to produce water safe for consumption.

Discuss the food and its handling process Safe steps in food handling, cooking, and storage are essential to prevent foodborne illnesses. In every step of food handling, following five key rules should be followed: i. Keep Clean  Hands should be washed thoroughly before handling food and often during food preparation  Hands should be washed after going to the toilet.  All the surfaces and equipments used for food preparation should be washed and sanitized.  Kitchen areas and food should be protected from insects, pests and other animals. ii.

Separate raw and cooked food  Raw meat and poultry should be separated from other foods.  Separate equipment and utensils such as knives and cutting boards can be used for handling raw foods.  Foods should be stored in containers to avoid contact between raw and prepared foods.

iii.

Cook thoroughly  Food should be cooked thoroughly, especially meant, eggs and poultry.  Foods like soups should be brought to boiling to make sure that they have reached 700C. For meat and poultry, it should be ensured that juices are clear, not pink.  Cooked food should be reheated thoroughly.

iv.

Keep food at safe temperatures  Cooked food should not be left at room temperature for more than 2 hours.  All cooked and perishable food should be refrigerated promptly (preferably below 5 0C.  Cooked food should be kept piping hot (more than 60 0C) prior to serving.  Food should not be stored too long even in the temperature.  Frozen food should not be thawed at room temperature.

Use safe water and raw materials 46

    

7.4

Safe water should be used or should be treated to make it safe. Fresh and wholesome foods should be selected and purchased. Foods processed for safety such as pasteurized milk should be chosen. Fruits and vegetables should be washed well, especially if eaten raw. Food should not be purchased and used beyond its expiry.

Discuss personal hygiene

Personal hygiene is a measure taken at individual level to promote personal cleanliness so that transmission of diseases from source to susceptible hosts is prevented. An important way to prevent food contamination is to maintain a high standard of personal hygiene and cleanliness. Some of the common personal hygiene measures to be followed in food processing and handling are as follows:  Wearing a hat/hairnet that completely covers the hair. Not combing hair in a processing room or storeroom.  Covering all cuts, burns, sores and abrasions with a clean, waterproof dressing.  Not smoking or eating in any room where there is open food because bacteria can be transferred from the mouth to the food.  Not spit, coughing or sneezing in a processing room or storeroom.  Washing hands and wrists thoroughly with soap after using the toilet, eating, smoking, coughing, blowing nose, combing hair, handling waste food, rubbish or cleaning chemicals. Drying hands on a clean towel before handling food again.  Keeping finger nails cut short.  Not wearing perfume or nail varnish as these can contaminate products.  Not handling any food if one has sores, boils, septic spots, a bad cold, chest infection, sore throat or a stomach upset. 7.5

Discuss hygiene in the kitchen Some of the important hygiene measure to be followed in the kitchen includes: i. Keeping kitchen equipments clean - Microorganisms can easily breed in dirty equipments, but if the machines and equipments are properly cleaned, the germs have nothing to feed on and cannot grow. - Therefore machines and kitchen equipments should be cleaned with hot water and detergent immediately after use. ii. Regularly cleaning kitchen between tasks using clean-preferably disposable cloths - Kitchen should be thoroughly cleaned after each work step. 47

Dirty cloths that have been reused often contain a high number of micro-organisms that are transferred to kitchen surfaces or equipment during cleaning. Therefore fresh cloths or disposable cloths should be used every day.

iii. Storing detergents and disinfectants outside the kitchen - Cleaning agents, disinfectants and pesticides can contaminate food. So they must not come in contact with food and must therefore be stored outside the kitchen. iv. Not touching prepared meals and the interior surfaces of crockery with bare hands - Microorganisms are always present on our hands and can be transferred to food or crockery/ cutlery if touched with bare hands. - Therefore, clean gloves should be used when portioning or mixing food that will not be subsequently heated. - The interior surfaces of crockery should not be touched with bare hands. v. Covering meals - Food should always be covered before storage to ensure that it is protected from microorganisms in the air. - Suitable ways covering food include lids, clean crockey or food-safe film or foil. vi.Tasting food in the proper manner

7.6

When tasting food, care should be taken to ensure that saliva does not come into with the food being prepared. A clean spoon should be use to take a small sample of the food and then tipped into a small bowl or directly onto another spoon intended to use for tasting. This ensures that the food itself remains untainted.

Explain cleaning & sanitizing, method of washing, rinse Cleaning is a process which will remove soil and prevent accumulation of food residues which may decompose or support the growth of disease causing organisms or the production of toxins. The main purpose of cleaning and sanitizing dishes is to remove visible surface dirt and reduce the level of bacteria to a safe level so as to  Reduce health hazard by avoiding contamination  Prevent spoilage of food  Control odor  Create a pleasing appearance Cleaning agents include the following: 48

Cleaning agent Soap

Advantages

Disadvantages

 Good cleanser  Good for hand-washing

 Poor rinsing quality; lot of water is required for rinsing  May form insoluble precipitate with hard water  Not recommended for dishwashing  Ineffective against rust and firmly attached food deposits

Synthetic  Remove dirt, grease and food soil detergents  Effective in hard water  Useful for manual and machine dishwashing and cleaning food contact surfaces  No undesirable action on hands Acid  Remove salt deposits in sinks and cleaners machines  Remove water spots  Used for removing rust stains  Removes tarnish from copper and brings back the glow Abrasive  Remove soil which acidic and cleaners alkaline cleaners cannot, e.g firmly attached scorched, baked-on deposits  Can clean rusty  Cleans badly soiled floors

 Harsh on the hands  Should be used with caution as they can damage the surface being cleaned

 May roughen the surface and increase chances of future dirt accumulation  Not advised for normal cleaning

Steps of cleaning i.

ii.

Pre-wash: The removal of gross food particles before applying the cleaning solution. This may be accomplished by flushing the equipment surface with cold or warm water under moderate pressure. Washing: the application of the cleaning agent. There are many methods of subjecting the surface of equipment to cleaning agent and solutions.  Soaking: Immersion in a cleaning solution. The cleaning solution should be hot and the equipment permitted to soak for 15-30 minutes before manually or mechanically scrubbed  Spray method: spraying cleaning solution on the surface. This method uses a fixed or portable spraying unit with either hot water or steam. 49

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Foaming: utilizes a concentrated blend or surfactant developed to be added to highly concentration solution of either alkaline or acid cleaners. It produces stable, copious foam when applied with a foam generator. The foam clings to the surface to be cleaned, which increases contact time of the liquid with the food, and prevents rapid drying and runoff of the liquid cleaner, thereby improving cleaning.  Jelling: utilizes a concentrated powdered-jelling agent which is dissolved in hot water to form a viscous gel. The desired cleaning product is dissolved in hot gel and the resulting jelled acid or alkaline detergent is sprayed on the surface to be cleaned. The jelled cleaner will hold a thin film on the surface for 10 minutes or longer to attack the soil. Soil and gel are removed with a pressure warm water rinse.  Abrasive type powders and pastes are used for removing difficult soil. Scouring pads should not be used on food-contact surfaces because small metal pieces from the pads may serve as focal points for corrosion and may be picked up in the food. iii. Rinse: the removal of all traces of the cleaning solution with clean potable water. iv. Sanitization Sanitizing is a reduction in the number of disease causing bacteria to safe levels. This is achieved through the use of heat or the application of chemical compounds. All food contact surfaces must be cleaned first and then sanitized as any kind of dirt interferes with the action of chemical sanitizers. Sanitizing is achieved by using chemical sanitizers or hot water. Guidelines for optimum sanitization  Choose hot water or heat for sanitization wherever possible  Use a chemical disinfectant only when the application of health is impossible.  Clean equipment and surfaces well before sanitization by health or chemical solution.  Choose a chemical disinfectant which is effective against a wide range of bacteria  Sanitize either by immersing the object in the correct concentration of sanitizer for one minute, or rinse, swab or spray double the recommended concentration of sanitizer on the surface to be sanitized and let the surface dry.

Various methods to wash, rinse and sanitize

Method of cleaning and sanitizing food contact surfaces

UNIT 8: FOOD ACCEPTANCE AND PURCHASING 8.1

Factors affecting the acceptance of food

Factors Affecting Food Choice and Acceptance

8.2

Discuss purchasing of safe foods Following considerations should be made for purchasing of safe and wholesome foods:  Only pasteurized milk and well-inspected meat and poultry should be purchased.  “Expiry” and “best before” dates should be checked and purchase food accordingly.  Canned goods in tins that are dented, rusted, bulging, or cracked should not be purchased as contents may be contaminated.  Food should not be purchased from unrefrigerated displays that should be in a cooler.  Eggs that are cracked or not refrigerated should not be purchased.  Cold and hot food should be purchased last when shopping, so it will have the least amount of time to change temperature before getting it home/hotel.  Raw meat products should be kept separate from other products in the shopping cart. These products should be placed in plastic bags at checkout, to prevent juices from leaking or contaminating other foods. 52

8.3

Discuss receiving of safe foods The goals of receiving safe food are i. To make sure foods are fresh and safe when they enter the hotel/facility ii. To transfer them to proper storage as quickly as possible. There are several important guidelines to keep in mind and tasks to complete as the person/facility is ready to receive food:  It should be ensure that the receiving area is equipped with sanitary carts for transporting goods.  It should be planned ahead for deliveries to ensure sufficient refrigerator and freezer space.  All the items for storage should be marked with the date of arrival or the “use by” date.  The receiving area should be kept well lit and clean to discourage pests. When the food delivery arrives, it should be ensured that the food looks and smells clean and is equipped with the proper food storage equipment. Then, following inspection of food should be done:  Checking expiry dates of milk, eggs and other perishable goods.  Making sure shelf-life dates have not expired.  Making sure frozen foods are in airtight, moisture-proof wrappings.  Rejecting foods that have been thawed and refrozen. Looking for signs and thawing and refreezing such as large crystals, solid areas of ice or excessive ice in containers.  Rejecting cans, that have any of the following: swollen sides or ends; flawed seals or seams; dents or rust. Also cans with any foamy or bad smelling contents should be rejected.  Checking temperature of refrigerated and frozen foods, especially eggs and dairy products, fresh meat, and fish and poultry products.  Looking for content damage and insect infestations.  Rejecting dairy, bakery and other foods delivered in flats or crates that are dirty.  Making sure that the packages of food products are not leaking and intact.

UNIT 9: FOOD AND PUBLIC HEALTH 9.1

Discuss food hazards Food Hazard means a biological, chemical or physical agent in, or condition of, food with the potential to cause an adverse health effect. Hazards may be introduced into the food supply any time during harvesting, formulation and processing, packaging and labeling, transportation, storage, preparation, and serving. i. Biological Hazards  Biological hazards occur when hazardous or pathogenic organisms are introduced to food and thus pose a food safety concern to consumers.  Biological hazards include bacteria, viruses and parasites of public health significance.  Ingesting food contaminated with pathogenic microorganisms and/or their toxic by-products can lead to food-borne illness. These illnesses can take the form of infection or intoxication, or both. ii. Chemical hazards  Chemical hazards occur when chemicals are present in foods at levels that can be hazardous to humans.  In the food system, there are various types of chemical hazards, some notable ones include: o Mycotoxins o Natural Toxins o Marine Toxins o Environmental Contaminants o Food Additives o Processing-induced chemicals o Pesticides/Agricultural Products and o Veterinary Drug Residues iii. Physical hazards:  Physical hazards cover all materials (excluding bacteria and their by-products (toxins), viruses and parasites) which may be found in a food that are foreign to that particular food.  These materials are usually non-toxic but are associated with unsanitary conditions of production, processing, handling, storage and distribution of food.  Some examples of extraneous physical materials that may be found in food are insects, hair, metal fragments, pieces of plastic, wood chips and glass.



9.2

Extraneous material can be considered hazardous due to its hardness, sharpness, size or shape. It may cause lacerations, perforations and wounds or may become a choking hazard.

Explain food borne disease Food borne disease is often referred to generally as “food poisoning”. A Food borne disease has been defined by WHO as “any disease of an infectious or toxic nature caused by or thought to be caused by the consumption of food or water”. Food borne diseases can be classified into two broad categories: i. Food Borne Infection:  A food borne infection is caused by ingestion of food contaminated by viruses, bacteria or parasites, and occurs in one of two ways: o o

 

Viruses, bacteria or parasites in ingested food invade and multiply in the intestinal mucosa and/or other tissues. Bacteria in ingested food invade and multiply in the intestinal tract and then release a toxin or toxins that damage surrounding tissues or interfere with normal organ or tissue function.

Symptoms of infection usually include diarrhea, nausea, vomiting and abdominal cramps. Fever is often associated with infection. Some of the major food borne infections are listed in the table below: SN Category Infections 1 Bacterial Typhoid fever and paratyphoid fever Other Salmonella infections Clostridium perfringes illness caused by enterotoxin released by Clostridium perfringes Bacillus cereus gastroenteritis caused by enterotoxin released by Bacillus cereus Diptheria Bacillary dysentery(shigellosis) Streptococcal sore throat Anthrax, brucellosis, tuberculosis 2 Viral and Infectious hepatitis rickettsial Q Fever 3 Protozoal Amoebic dysentery 4 Zooparasitical Taeniasis, ascariasis, etc.

ii. Food Borne Intoxication:  A food borne intoxication is caused by ingestion of food already contaminated by a toxin. Sources of toxin are: o

Certain bacteria, 55

o o

 

9.3

Poisonous chemicals (e.g., heavy metals like copper), or Toxins found naturally or formed in animals, plants or fungi (e.g., certain fish and shellfish, certain wild mushrooms).

Food borne intoxications most often result from bacteria that release toxins into food during growth in the food. Viruses and parasites are unable to cause The most common or sometimes only symptom of intoxication is vomiting. Other symptoms can range from nausea and diarrhea to interference with sensory and motor functions (e.g., taste, touch, muscle movements). These include: double vision, weakness, respiratory failure, numbness, tingling of the face and disorientation. Fever is rarely present with intoxication Some of the major food borne intoxications are listed in the table below: SN Category Infections 1 Bacterial origin Botulism caused by toxin produced by Clostridium botulinum Staphylococcal enterotoxin food poisoning caused by toxin produced by S. aureus 2 Food borne Intoxications caused by fish and plant toxins intoxications due to Intoxications caused by inorganic and organic chemical poisons compounds in food 3 Fungal Mycotoxicosis

Discuss symptoms of food poisoning Symptoms from the most common types of food poisoning will often start within 2 - 6 hours of eating the food. That time may be longer or shorter, depending on the cause of the food poisoning. Possible symptoms include:  Abdominal cramps  Diarrhea (may be bloody)  Fever and chills  Headache  Nausea and vomiting  Weakness (may be serious) Some of the major symptoms of food poisoning based on causative agents are as follows: SN Agents Main Symptoms 1 Staphylococcus aureus enterotoxin Vomiting 2 Clostridium perfringes enterotoxins Abdominal pain and to a lesser extent watery diarrhoea 3 B cereus enterotoxins Watery diarrhea and to a lesser extent abdominal pain 56

4 5

9.4

Non-typhoidal Salmonella; Compylobacter; Vibrio Clostridium botulinum

Febrile watery diarrhea Neurological (ptosis, diplopia, poor accommodation, dysphagia, dyspnoea, constipation and paralysis of facial, intercostal and skeletal muscles

Discuss Natural toxicants in food, toxic metals and chemicals

SN Category Diseases

Toxicants

Foods commonly involved

Beta-oxalyl amino-alanine (BOAA) Phalloidine and alkaloids found in some poisonous mushrooms Sanguinarine Solanine

Lathyrus sativus (Khesari dal)

Natural toxins in food

Fungal toxins

Neurolathyrism Mushroom poisoning Epidemic dropsy Solanine Poisoning Ergotism

Aflatoxin food poisoning

Chemical Lead, mercury, and heavy cadmium poisoning metals Arsenic, Fluoride Poisoning Chemical Poisoning

Poisonous mushrooms such as species of Amanita phalloides and Amanita muscaria Argemone Mexicana (Dhaturo) Potato, tomatoes, peppers

A toxin (ergot) produced by a group of fungi called Claviceps purpurea

Rye, wheat, sorghum, barley

Aflatoxin produced by some groups of fungus (e.g. Aspergillus flavus, Aspergillus parasiticus) lead, mercury, cadmium

Cereal grains, groundnuts, peanuts, cottonseed, sorghum

Arsenic, Fluoride Pesticides and insecticides

Fish, canned food Foods contaminated by utensils or coated with heavy metals Any foods accidently contaminated Residues on crops, vegetables, fruits Accidental poisoning where some chemicals may be mistaken for food ingredients When contaminated containers are used to hold stored foods

Persistent Organic Pollutants (POPs) such as Dioxins and PCBs 57

Any foods accidently contaminated

9.5

Explain factors associated with food borne illnesses Some of the major factors associated with food borne illness outbreaks are:  Improper hot/cold holding temperatures of potentially hazardous food  Improper cooking temperatures of food  Dirty and/or contaminated utensils and equipment  Poor employee health and hygiene  Food from unsafe sources When food is being prepared by either the public in their home, or by a food facility operator, the presence of one or more of these risk factors dramatically increases the risk of a food borne illness outbreak. i. Improper hot and cold holding temperatures of potentially hazardous foods  The purpose of holding potentially hazardous foods at proper temperatures is to minimize the growth of any pathogenic bacteria that may be present in the food.  The number of bacteria that a person ingests with their food has a direct impact on a possible illness.  Holding potentially hazardous foods at improper temperatures may allow pathogenic bacteria to reproduce rapidly and progressively to great numbers, thus putting someone who eats that food at great risk for food borne illness. ii. Improper Cooking Temperatures of Foods  Cooking food to the proper temperatures is extremely important because many raw meats have pathogenic bacteria on them naturally, such as salmonella on raw chicken.  Cooking is the only food preparation step that will actually kill bacteria.  Proper holding temperatures slow down reproduction, freezing food makes bacteria go dormant, but proper cooking temperatures will kill bacteria that are in the food. iii. Dirty or Contaminated Utensils and Equipment  When utensils or equipment become dirty or contaminated, they can transfer that contamination to the food causing a food borne illness.  This may occur in a number of different ways. If utensils or equipment are not cleaned frequently, and old food residue is allowed to build up at room temperature, bacteria in the residue may multiply rapidly and contaminate any food that comes into contact with it.  A specific kind of contamination can occur when ready-to-eat foods come into contact with raw animal products or their juices. This is called crosscontamination.



Utensils, equipment, and food contact surfaces may also be contaminated by other means. If they come into contact with dirty mop water, garbage, pesticides, sewage, or anything else that could potentially cause illness.

iv. Poor Employee Health and Hygiene  A food worker that has been diagnosed with an acute gastrointestinal illness, or is showing symptoms such as diarrhea, or vomiting in conjunction with diarrhea, could potentially contaminate food and cause food borne illness.  It is possible for a food worker to transfer their illness to customers via the food.  Even there is the potential for employees working with large batches of food to spread the illness to numerous people causing an outbreak v. Food from Unsafe Sources  Majority of the biological and toxic agents that cause food borne illnesses originate from sources early in the food handling chain, before the food enters the kitchen.  Foods from unregulated sources pose the greatest risk of contamination with biological, chemical and physical agents.

9.6

Explain control and eradication of microorganisms, flies, cockroaches and rodents Control of microorganisms: Methods used to control the microorganisms and their transmission of infectious disease involves stopping their growth for a period of time, reducing the number of microorganisms to a safe level or destroying the microorganisms. i. Heat methods: Health is the most common, inexpensive, simplest but effective method used to destroy microorganisms. Health denaturates the proteins and enzymes of microorganisms. The heat used in sterilization is either moist or dry. a. Boiling: Bacteria, fungi and many viruses are destroyed by boiling at 100 for 10 to 30 minutes. Some viruses and endospores may require boiling for up to 20 hours. b. Steam under pressure: The most common device used is an autoclave. At a pressure of 15 pound/ sq. inch, and a temperature of 121 0C for 15 to 20 minutes it will destroy microorganisms and endospores. c. Pasteurization: It is mainly used in the food and dairy industries and it involves raising the temperature high enough to destroy pathogens or inhibit their growth without affecting the quality of product. 59

iii. Cooling: The effect of low temperature on microorganisms depends on the type of microorganisms and the intensity of cold application. Temperature in a refrigerator ranges from 0-80C and has a bacteriostatic effect which reduces the metabolic rate of most organisms. Freezing at -200C kills most bacteria, but some may survive in a frozen state. iv. Drying or dessication: To grow and multiply, microorganisms require water. The removal of water by evaporation or freeze-drying inhibits growth and reproduction of microorganisms by inhibiting enzymes. They may be viable for years so when water is made available, they resume growth and reproduction v. Application of UV and ionizing radiation: Both types of radiation damage the DNA of microorganisms and denaturates their proteins vi. Use of chemical agents: Chemical agents are used to control the growth of microorganisms on food. Most chemical agents reduce the number of microorganisms but do not achieve sterility. Some of the common disinfectants used in food are Butylated Hydroxy Anisole (BHA), Butylated Hydroxy Toluene (BHT), Propyl Gallate, Natural/Synthetic Tocopherols (Vitamin E), Ascorbic Acid (vitamin C), Lecithin, Lactic acid, etc. Control of flies Control methods of files can be divided into three categories i. Physical and mechanical control  Flies can be prevented from entering building by screening windows and other opening.  Mesh size of 3-4 strands per cm will exclude houseflies from buildings.  Air currents, such as air barriers found in entrances of some shops, and fans mounted over doorways may reduce the number of flies entering premises.  Placing curtains of vertical, often colored, strips of plastic or beading in doorways also help keep out flies.  Restaurants, food stores often mount ultraviolet light traps on walls to attract flies, which are then killed by an electric grid.  Commercially available sticky tapes (fly-papers) incorporating sugar as an attractant can be relatively effective.  Food should be covered well. ii. Environmental sanitation  Environmental sanitation aims at reducing housefly populations by minimizing their breeding places. For e.g, domestic refuse and garbage should be placed 60



either in strong plastic bags with the openings tightly closed or in dustbins with tight fitting lids. Households refuse should be burnt or buried.

iii. Insecticidal control  Larvicides can be directed against larvae by spraying the insides of dustbin and refuse and garbage heaps, manure piles and other breeding sites.  Commerical aerosol spray cans or hand sprayers can be used indoors to spray insecticides to give an immediate kill of adult flies.  Flies may also be controlled by spraying indoor walls, ceilings, doors, etc with malathion, propoxur, cypermethrin or permethrin or deltamethrin.  Baits can sometimes quiclkly reduce fly populations. Toxic baits (consisting of sugar mixed with bran and treated with insecticides) can be scattered on floors or placed intrays. Prevention and control of cockroach Heavy infestations of cockroaches can be dealt with by chemical control measures, followed by environmental management to deprive the insects of food and shelter. Low numbers can be effectively controlled by baits or traps. i. Environmental management a. Cleanliness and hygiene  Food should be stored in tightly covered containers in screened cabinets or refrigerators.  All areas have to be kept clean so that no fragments of food or organic matter remain.  Rubbish bins should be securely covered and emptied frequently, preferably daily.  Basements and areas underneath buildings should be kept dry and free of accessible food and water. b. Reduction of accessibility  Groceries, laundry, dirty clothing, egg crates and furniture should be checked before being taken into a building.  In some instances, accessibility to buildings can be reduced by closing gaps in floors and door frames. Openings for drain water and sewer pipes, drinkingwater and electricity cables should also be closed. ii. Chemical control  Cockroaches are difficult to control with insecticides for several reasons, one of which is that they may become resistant to commonly used compounds. Moreover, many insecticides are repellent to them and are therefore avoided 61

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Insecticides are applied to the resting and hiding places as residual sprays and insecticidal dusts. Such applications are effective for periods ranging from several days to months, depending on the insecticide and the substrate on which it is deposited. Insecticides can also be combined with attractants as toxic baits.

Control of rodents The prevention and control of rodents are achieved by following methods i. Eliminating the hiding and nesting sites:  Keeping surroundings clean and free from debris to prevent rodents’ entry and breeding in the premises.  Good housekeeping will prevent hiding and nesting places to rodents.  Make all openings to construction rodent proof through engineering methods. ii. Eliminating food sources  Spillage should be cleaned daily  Garbage should not be stored outside in plastic bags as plastic bags are not rodentproof, instead metal bins or heavy duty plastic bins with tight-fitting lids should be used.  Pet food dishes and leftovers should be promptly removed after breeding.  Food grains or other food materials should be stored in rodent proof containers wherever feasible. iii. Trapping  Trapping can be effective method of controlling rodents, but it requires more skill and labor than other methods.  For successful trapping, it is advisable that baited traps should be placed.  The traps either trap live rodents or kill the rodents. The commonly available traps are cage traps, Sherman traps, trigger or snap traps, break back traps. iv. Baiting  The process of baiting utilizes special chemicals called rodenticides for killing the rodents.  The use of rodenticides (zinc phospide, barium carbonate, etc.) or the process of baiting should be undertaken by trained individuals and require utmost care as they pose threat to non target organisms, as well as hazards of accidental poisoning. v. Fumigation

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Fumigation is the choice method for killing rodents in burrows, enclosed structures/places. It is usually carried out by trained professionals due to the risk posed by the noxious gases released during the process. The fumigants commonly used are Aluminium phosphide and calcium cyanide. Sulphur dioxide, carbon monoxide and methyl bromide are used especially in godowns, granaries, etc.

UNIT 10: KITCHEN SAFETY 10.1

Why accidents should be prevented Accidents should be prevented because they have a direct or indirect effect on individuals and the establishment. Direct effect of accidents i. Injury: Accidents result in injury which can cause much pain and absenteeism from work. Unattended wounds may become a source of infection. ii. Expenditure: Accidents are expensive. Frequent accidents will result in additional to the management. Indirect effects of accidents i. Damaged or broken material ii. Reduced efficiency: if an area is accident-prone, workers try to avoid accidents and work slowly; other staff will be engaged in attending to the inkured, cleaning up the mess, doctor visits and investigations iii. Work schedule and routine is upset: work is completed in a hurry and hygienic aspects tends to get overlooked in an attempt to just complete the job iv. Injured workers may have to stay away from work and need to be replaced, resulting in training of new employees or being under staffed v. Accidents can result in fines or imprisonment: under the labor law, accidents in food service operation may face legal action.

10.2

Explain how accidents take place There are two major factors how accidents takes place i. The Human Factor (Careless, negligent and slack food handler) - In most of the cases, it has been noticed that people are responsible for most of the accidents as they are the ones who create unsafe conditions. - The may be careless, for example.  Pick up broken glass with bare hands  Ignore operating instructions on equipments  Lift very heavy loads alone  Do not use safety devices on grinders and slicers - They may be inattentive, for example,  Bump into other people  Drop heavy items or spill hot liquids on their own feet  Close doors and drawers on their own fingers and squash them  Rush with arms full and minds elsewhere on wet greasy follors ii. -

Unsafe workplace The layout may be badly planned or conditions in the kitchen may be conducive to unnecessary accidents. 64

Unsafe surroundings are results of the following:  Steep, marrow, dark stairways  Unnecessary steps  Clogged floor drains  Ladders too short to reach uppermost shelves so boxes are used instead  Unprotected meat slicer blades  Doors opening into corridors  Knives left lying around  Handles of pots and pans protruding outwards

In summary, accidents take place due to the following reasons:  Carelessness, lack of concentration or being distracted by something when carrying out a task.  Work areas are sometimes small and cramped with poor lighting increasing risks of accidents  Operations of faulty equipment and machinery can also cause accidents.  Poor storage of supplies and obstructions in walkways creating a difficult access  Spills and slippery floors also can result in accidents.  Incorrect lifting of heavy objects  Faulty or frayed electrical appliances.

10.3

Explain the types of accidents  Falls and collisions - Workers may slip and fall on floors made of slippery material- floors may be slippery because of grease, fruit and vegetable peels and water on the floor or workers footwear may have slippery soles - Workers may fall from a height while trying to reach for things- they climb on unsafe boxes, chairs, shelves and rickety ladders - Workers may collide with other people, equipment, furniture, etc. damaging it as well as hurting themselves or - Workers may trip and fall by getting stuck in physical objects. 

Cuts - Cuts and lacerations can be caused in the kitchen due to following reasons:  Careless handling of knives, food slicers, choppers, mixers, broken glass, etc by untrained employees during the rush hour  By sharp edges of badly designed equipment and  By following incorrect practices such as catching knives as they fall, leaving them in a dishwater in sinks or washing then in dishwashing machine or using blunt knives which need a lot of pressure to cut with.

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Burns and scales - Burns and scalds are the second most common accidents in the kitchen. They result in injury of varying degrees of severity. - They are caused by contact with  Hot surfaces of grills, ovens, griddles, burners, etc.  Hot water or steam from boilers and steamers  Spillage or splashes from hot food or drink  Hot fat from frying pans, deep fat fryers and  By using defective equipment like loose handles on utensils, faulty tongs, etc.

Other types of accidents include,  Fires  Electrical shocks  Bites and stings  Poisoning  Inhalation of foreign bodies 10.4

Explain how to prevent cuts The food service workers need to be careful not to get cut. In order to prevent cut, following precautions are required: 

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Appropriate tools (not bare hands) should be used to pick up and dispose of broken glass. Broken glass should immediately be placed into a separate, clearly marked garbage container. Care should be taken when cutting rolls of kitchen wrap with the cutter. Care should be taken with can openers and the edges of open cans. Knife should not be used to open can or to pry items loose. Pusher should be used to feed food into a grinder. Slicers and grinders should be turned off and unplugged when removing food and cleaning. Guards or grinders and slicers should be used. Equipment blades should be replaced as soon as they are cleaned. Broken glassware should be handled with care

Additionally,  Knives should be kept sharp. Dull blades are harder to work with and cause more cuts than sharp ones.  Knives or equipments should not be left in the bottom of the sink. 66

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Knives should be carried by the handle with the tip pointed away. It should never be tried to catch a falling knife.

When storing or cleaning equipment, it is necessary to ensure that  Knives and other sharp tools are stored in special places when not in use.  Dishes and glasses are washed separately to help prevent them from being crushed by heavier objects and breaking in the dishwasher or sink.  Glasses or cups should not be stacked inside on another.  Nails, staples and protruding sharp edges should be watched out while unpacking boxes and crates. 10.5

Explain how to prevent burns There are many ways person can get burned in a food service environment. Burns can result from contact with hot surfaces as grills, ovens, burners, fryers and other heating equipment. Burns can also be caused by escaping steam or hot food or drinks that are splattered, splashed or spilled Following measures can be taken to prevent burns:             

10.6

Thick, dry potholders or mitts should be used and food should be stirred with long handled spoons or paddles. Hot water faucets (taps, mixtures) should be turned on cautiously. Insulated rubber glove should be wore for water that is more than 75 0C. Instructions should be followed for the use of cooking equipment-particularly steam equipment. It should be ensured that all steam is expelled from steamers before opening the lids. Cooking lids and similar equipment should be lifted away to avoid burns from steam. To avoid splattering and splashing, kettles should not be filled full. Also food should not be allowed to boil over. Cooking surfaces should not be crowded with hot pans. Cooked foods should be removed from cooking surfaces immediately. Oil should be allowed to cool and extreme caution should be used when cleaning fryers. Caution should be used when removing hot pans from the oven. Insulated gloves or mitts should be worn. Clothing that may drape onto a hot spot and catch a fire should not be worn. All employees should be trained on use of fire-extinguisher, through fire drills.

Explain how to prevent falls In order to prevent slips and falls, following precautions should be used: 67

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Wet spots and spills, particularly on the floors should be cleaned immediately. People should be cautioned when floors are wet. Spills should be mopped. Shoes that have no-slip soles should be used. Boxes or other objects should not be stacked too high; they can fall and cause people to trip. Items such as boxes, ladders, step stools and carts should be kept out of the paths of foot traffic. Floors, flooring and stairs should be well maintained. Torn carpets, loose tiles, broken floors, loose steps, loose electrical wires, or other obstruction should be attended at once. Stepladder of sufficient height should be used to reach objects at high location. Adequate lighting is also essential. Traffic lines should be kept clean, dry and free from obstructions.

Sources:  Safe Food Handling: A training guide for managers of food service establishments; WHO Geneva M. Jacob, 1989.  Encyclopedia of Restaurant Training- A complete ready to use training program for all positions in the food service industry; Lara Arduser & Douglas Robert Brown 2005 Atlantic Publishing Group.Inc  Food Science Text Series Essentials of Food Hygiene-Third Edition; Vaclavik V. A., Christian E.W.;Springer, 2008  The Hospitality Industry Handbook on Hygiene and Safety; Lisa Gordon-Davis,South Africa, 2008