Bangladesh has vast fisheries resource and the climatic condition is suitable for fish production Chapter 1 INTRODUCTION 1.1 Statuses and Importance of Fisheries in Bangladesh According to the World Bank Bangladesh has vast fisheries resource and the climatic condition is suitable for fish production. Fisheries resource of Bangladesh includes inland water resource and marine water resource. In all seasons and all levels of technological progress, fishes have usually played an essential part in human diet. Most people in developing countries are still depending almost entirely on fish as a source of animal protein. Fishes supply more than 80% of animal protein in the diet of the people of Bangladesh (Rubbi et-al. 1978), 85-95% of fish proteins are digestible and all dietary essential amino acids are present in fish (Nilsons 1946; Deano and Tarry 1949). Ali (1970) pointed out that fish supplies 32.8 g. of protein per person per day out of 57.0g. The fresh water fishes are the most important sources of protein for Bangladesh. In developing countries like us there is a need to increase food production hence the flood plains are the vital resource to meet up the increasing demand of animal protein. Haque (1976) reported that the intake of animal protein per person in Bangladesh was approximately 7.9 g / day which means 32% of normal requirements of 25g. of an adult. This indicates that there is protein deficiency in Bangladesh. Fish is most important items in our dietary chart. It has been reported that near about 8% of the total population in Bangladesh directly depend upon fishing and its ancillary industries for the sake of their livelihood (Karim, 1978). Karim (1978) reported that fish account for about 80% of the countries animal protein supply and 9% of its GDP.
In 1962-63 per capita fish consumption was about 33g whereas at present it is 22g per capita. In other hand minimum requirement of 73g of fish per head per day (BARC 1982) The Bangladesh Fisheries can broadly be divided into (i) Inland or Freshwater Fisheries and (ii) Marine Fisheries. The inland fisheries of Bangladesh are considered to be extremely formidable in terms of natural water areas and its potential for shrimp and fish culture. Inland fisheries contributed to 74.90% of the total fish catch of the country in 1992-93.It includes innumerable rivers and their tributaries, baors, haors and the estuaries. The main river systems in Bangladesh include the Meghan, the Padma, the Jamuna, the Brahmaputra and the Karnaphuli and their tributaries-the total water area of which is over, 1.03 million ha. There are many ox-bow lakes locally called ‘Baors’ formed due to silting up of old rivers in the districts of Jessore, Jenaidah, Court Chandpur, Kustia and Faridpur with a total water area of about 5,488 ha. The natural depressions of land are used partially as agricultural lands in dry seasons and seasonally or perennially filled with water from adjacent rivers during rainy season. Most of these haors are located in the greater Sylhet, Mymensingh and Faridpur districts. The total water areas of the haors in Bangladesh are about 1, 14,161 ha. The Kaptai Lake one of the largest man-made lakes consists of 68,800 ha. The total open water areas of the country are about 4.05 m ha from which a total of 533,000 MT of fish was caught in 1992-93. Floodplains are the integral parts of Bangladesh’s inland aquatic resource system that extends some 4.3 million ha of water bodies. In addition about 5.5 million ha of rice fields, which are intermittently inundated during the monsoon to a depth of 30 cm or more, form parts of aquatic production system. Together they form the vast inland capture fisheries which offer significant livelihood opportunenities to the population and produce the bulk of the annual supply of animal protein. The floods create a vast productive expanse into which the fish migrate seasonally for feeding and reproduction. 60% of the known fresh water fish species in Bangladesh are floodplain dependent (Boyce 1991). Flood lands through subsistent fishing produce 186, 000 MT (Rahman 1993). An estimated 10.8 million house holds (73%) take parts in fishing activities in flood plains (World Bank 1991).
Closed water bodies include large-sized ponds called dig his, ponds and tanks. There are about 1.29 million ponds covering over 1, 46,890 ha. of water areas of which about 76,632 ha are under fish culture, 48,814 ha culturable and 25,450 ha. of derelict ponds. Of the total water areas of the ponds 52.17% are now under fish culture, 30.51% easily culturable but now idle and 17.32% are derelict which can be turned into good fish ponds after proper renovation them. Out of the total number of 1.29 million ponds about 46.48% are under culture, 29.90% culturable and rest 23.62% are derelict ponds. The estimated fish production of all these ponds were only 16, 6100 MT in 1986-87 and 24, 2572 MT in 1992-93. Even freshwater Shrimp (M. rosenbergii) can be cultured extensively to meet the demand of the processing industry. Total production of fish from freshwater fisheries was 60, 7645 MT in 1988-89 which increased to 77, 5472 MT in 199293. Drying is one of the most important methods of preservation of fish through out the world. Although drying is regarded as a traditional, even primitive method of fish preservation in many developed countries, it is still of vital importance in the less well developed regions of the world and will remain so for a long time to come (Waterman 1976). In Bangladesh sun drying is commercially practiced for large scale production of different kinds of dried fish. Most of the inland capture fish is consumed fresh. However the major portion of the marine fish, mostly caught during the winter season is sun dried in the traditional method (Rubbi et-al. 1978). According to the BFDC reports (1970-79) total quantity of dried fish production in Bangladesh was 45,000 – 50,000 MT. The major markets for dry fish during 1991-92 were ASEAN (80.08%), Middle East (10.66%), and E.E.C. (8.75%). In order to evaluate the nutritional value of fish it is essential to collect relevant information particularly on the biochemical composition. Some information on biological composition and nutritional status of fresh water fish of this region have been carried out by Khuda et-al. (1960, 1962), Kamaluddin et-al. (1977), Rubbi (1987), Gheyasuddin et-al. (1979,1980) and Fisheries Technological Research Station, Chandpur(1980). Information about the percentages of the edible and non-edible portion of different species of fresh water fishes with their quality assessment are entirely lacking.
The knowledge of biochemical composition of fish can help the dietician to make suggestions to the diet of the patient. The literature on the macro and micro nutrients content of indigenous fishes of Bangladesh is relatively small in comparison with the number of available species. Bangladesh is one of the developing countries in the present world with a vast population. The foremost nutritional problem always has been accrued. Though the indigenous small fish are not economical in the sense of status and are regarded as the fish of poor but they have the great importance in the national nutritional programme.Recently in Bangladesh some exotic fishes are introduced in open water although they are regarded for the close water pond culture. 1.2 Rationale Poor preservation condition and method of preservation of fish and fish product are the two major impediments in the fields of fish marketing around the world including Bangladesh. Poor quality of dried fish product is increasingly becoming an important impediment for the expansion and augmentation of fish processing and marketing in Bangladesh. Identification and determination of the attributes responsible for the deteriorating of fish product quality for example, proximate analysis, total volatile nitrogen (TVN) and trim ethyl amine (TMA) will provide information for further improvement and recommendations. 1.3 Problem Statement It is often said that fish product quality have been deteriorated due to improper preservation method resulting from insufficient handling and storage condition. Fish is an extremely perishable foodstuff. Spoilage of fish begins as soon as the fish dies or is caught. Some times spoilage occurs in the preserved fish like dried product. Poor handling and storage condition may deteriorate the product condition. Any improvement of the above mentioned quality parameter would benefit lots to the dried fish producers, fish product seller and finally the consumers.
1.4 Objectives The overall objective of this study was to improve the fish product quality and their effects of freezing condition on the dried pony fish. The specific objectives are: 1. to determine the dried fish quality 2. to determine effects of freezing condition the dried fish product; and 3. to determine the qualitative and quantitative changes of pony fish during short term freezing . 1.5 Activities 1. Designing the experimental layout; 2. Collection of experimental dried fish; 3. Measuring initial length (cm) and weight (g); 4. Stocking experimental fish into the systems; 5. Preparation of the sample; 6. Analysis of the sample; 7. Calculation the result; 1.6 Expected Out Comes 1. Better understanding the freezing of dried fish; 2. Understanding the role of freezing condition on the improving of dried fish quality. 1.7 Scope and Limitations The experimental analytical activities were done in the Institute of Food and Radiation Biology (IFRB), Atomic Energy Research Establishment (AERE), Savar, Dhaka. Current study dealt only with the effects of freezing condition on dried Pony fish, indicated by proximate analysis, TVN and TMA. Therefore rigorous long-term study is required before
dissemination the results of the current study to the benefices, the end users of fish processor and dried fish seller in home and overseas. Only three parameter ware studied and two condition ware applied in the current study due to insufficient facilities and time boundaries in the laboratory Chapter 2 REVIEW OF LITERATURE The literature required have includes few works on drying and dried products of fish with other dried foods which have direct relationship with present work.
2.1 Biochemical composition of fresh fish The literature required have includes few works on drying and dried products of fish with other dried foods which have direct relationship with present work. Drying of fish in order to preserve them during seasons of abundance for consumption during seasons of shortage is an ancient art. Man has been drying fish as a mean of preserving it ever since he first learned to fashion simple fishing implements from borne in Paleolithic times and a combination of drying and salting as a means of keeping lean fish had certainly become established by the bronze age (Waterman, 1976). Dried fish are in effect not only the cheapest animal protein in the world food market but also the most concentrated. It provides more than half of the nutritional value of the whole international tradition food fish. (Waterman 1976). It is an essential food for the poor in many less developed countries despite their commercial importance. Cured products dried and salted accounts for more than 62% of the world trade, 52% of which is fish and 10% shell fish (Borgstrom 1963). In India, 25% of her total catch is sun dried (Menon 1958). Open sun drying method although the earliest method of preservation yet about 50% dried fish was wasted, 30% during drying and 20% during storage as estimated by Doe et al.
(1977) in Bangladesh due to fly infestation. He also reported that 5-6 days of drying cause much loss through spoilage. Shaha and Chowdhury (1951) showed that the protein content of the locally cured fish was considerably lower than that of the fish dried by the Govt. yard in India. The ash content of locally dried fish was higher than the Govt. yard products. Martenik and Jacobs (1943), Doha (1964) indicated that nutritionally the dehydrated products are very good and neither the nutritive value nor the digestibility of the protein was adversely affected. Rahman et al. (1978) studied on the Rohu fish and showed no loss of proteins and lipids as a result of drying. Malek et al.,(1966) determination the moisture and ash contents in Puntius stigma and the results were 72.65% and 2% respectively. Rubbi et aim (1987) studies the proximate composition of 27 species of freshwater fish both scaly and non scaly fish and found the following result: Moisture: 72.1%-83.6% Protein: 11.9%-21.9% Fat: 0.8 %-15.0% Ash:0. 8%-5.11% 2.3 Materials and Methods 2.3.1 Materials The experimental sample consists of one type of dried fish. These is Harpoon nehereus (Hamilton-Buchanan, 1822)
2.3.1.1 Collection of specimen The dried sample was collected from the whole sale market of carwanbazar from Dhaka. All the samples were collected in 5th June , 2006 and stored in polythene bag at Food Technology Division of Institute of Food and Radiation Biology (IFRB), AERE, Savar, Dhaka at ambient temperature (¹ 28 0C) and 4-5°C temperature. 2.3.1.2 Identification of Specimen Plate (1) shows Harpodon nehereus (Hamilton-Buchanan, 1822).It belong to order Aulopiformes and commonly known as Bombay duck. Locally it is named as Latia, Latta.It is a marine water fish and found in fishing ground of Bay of Bengal especially in Swatch of no-ground. It is strongly compressed and mouth large. Teeth present and lower jaw is longer than upper jaw. P H value of the sample was 6.18. Taxonomic formula of the fish is Br. XXXIV-XXVI ; D. 12-14 ; P. 11-12; V. 9 ; A. 13-15; C.19 Fig 2.3.2 Methods Determination of spoilage Quality literally means degree or grade of excellence. It may also involve safety aspects such as being free from harmful bacteria, parasites or chemicals. It is important to remember that "quality'' implies different things to different people and is a term which must be defined in association with an individual product type. The quality changes of fish during spoilage were determined both by subjective and objective parameters as follows: 1.
Sensory methods by organoleptic score techniques of Shewan et. al ( 1957)
2.
Chemical indices such as TVN and TMA were determined by Conway micro -diffusion technique (Conway, 1968).
1. Organoleptic methods (Sensory evaluation): Organoleptic measurement of dry fish Harpodon nehereus (Hamilton-Buchanan, 1822) is different from fresh fish. For organoleptic assessment of quality of dried sample a test panel
consisting of 5 to 6 members was organized. They tested the samples before and after cooking. The samples were tested after 10days, 20days and 30days of storage. During organoleptic test the criteria considered before cooking were appearance, fungal infestation, odor, rarcidity and overall acceptability. The criteria considered after cooking were appearance, texture, flavour, rancidity, saltiness and overall acceptability. Cooking was done by boiling the sample for 5minutes. The panel members assessed the quality of the sample according to the following score sheet: Appearance: 1. Very good--------------------10 2. Good--------------------------8 3. Fair----------------------------6 4. Not bad-----------------------4 5. Bad----------------------------2 6. Very bad----------------------0 Fungal infestation: 1. No fungal infestation--------------------10 2. Trace fungal infestation-----------------8 3. Slight fungal infestation-----------------6 4. Moderate fungal infestation-------------3 5. Heavy fungal infestation-----------------0 Texture: 1. Normal cooked smoked fish-----------10 2. Slight tough-------------------------------8 3. Moderately tough-------------------------6 4. Tough-------------------------------------3 5. Very tough-------------------------------0
Flavour: 1. Flea sent smoky flavour----------------10 2. Good smoky flavour---------------------8 3. Moderate smoky flavour----------------6 4. Just smoky flavour-----------------------4 5. Strong smoky flavour--------------------2 6. Very strong smoky flavour--------------0 Rancidity: 1. No rancid flavour-------------------------10 2. Slight rancid flavour----------------------8 3. Moderate rancid flavour------------------6 4. Just rancid flavour-------------------------4 5. Rancid flavour-----------------------------2 6. Strong rancid flavour----------------------0 Saltiness: 1. Rightly salted-------------------------------10 2. Moderately salted---------------------------8 3. Less salted-----------------------------------4 4. Too much salted----------------------------0 Overall acceptability: 1. Highly acceptable--------------------------10 2. Acceptable-----------------------------------9 3. Moderately acceptable ---------------------8 4. Just acceptable-------------------------------6 5. Just unacceptable---------------------------5 6. Unacceptable-------------------------------3 7. More unacceptable-------------------------1
8. Extremely unacceptable------------------0 3.4.2Chemical indices such as TVN and TMA were determined by Conway methods. The sample was taken from whole body of the dried fish. According to Derrick 2 grams of muscle were used to prepare an extract for analyzing the TVN. Measurement of TVN and TMA was probable the first chemical method to be used as practical index of freshness and it is still the most popular. TVN and TMA have widely been used as an index for freshness of fish. According to Burgess et al., (1965) the upper limit of TVN is 30mg / 100g for acceptable condition for fresh raw fish. Three methods were used to determine TVN or TMA 1) The Conway micro-diffusion method 2) Semi micro steam distillation 3) And flow injection gas diffusion For the estimation of TVN and TMA Conway micro diffusion technique was used. This technique was carried out in the special glass dish called “Conway Dish� which had second concentric wall inside, thus having two separate chambers. For covering the Conway Dish glass lids were used. Preparation of the reagents: 1. 10% trichloroacetic acid ( TCA) solution 2. 2% boric acid solution a) 2g boric acid b) 22 ml alcohol c) 1ml mixed indicator d) 77 ml distilled water e) N/10 Noah was added up to a color of reddish was obtained. 3. Mixed indicator a) 0.1 % bromocresol green in 95 % alcohol
b) 0.1 % methyl red in 95 % alcohol c) 10 ml (a) + 2ml (b) mixed in a bottle 4. Saturated K2C03 (4 part K2C03 in 3 part DH2O) 5. Standardization of H2SO4 against K2C03 using methyl orange indicator prepared 0.1% in DH2O. 6. Formalin (30% formaldehyde solution) 3.5 Preparation of the extract: At first 2g of sample was taken from sample dried fish (Harpodon nehereus Hamilton-Buchanan, 1822 ) and was kept in 10% TCA solution over night in a conical flask. Then the sample was ground in a mortar with pestle with 10% TCA. Then the mixture was transferred in a measuring cylinder and was made to a volume of 25 cc by adding extra 10% TCA and filtered this extract by 80g filter paper. For the determination of TVN and TMA filtered extract was used. 3.7 Procedure for the determination of TVN and TMA: In the Conway dish into the inner chamber 2 ml of 2% boric acid solution was taken. Glass lid was used with grease for covering the side of the Conway dish in such a way that the outer chamber of the Conway dish was partially open. Then 2 ml of sample extract was taken into outer chamber and 2 ml of saturated K2C03 solution was added with sample. Then the lid was fixed quickly and left it over night at ambient temperature. On the following day titration at the residual boric acid solution was done by standard N/70 H2SO4 solution. To determine the TMA same procedure was followed. But in this case, in addition to the above reagents, 1 ml or 10-20 drops of formalin was added into outer chamber of the Conway dish. Blank Sample: The procedure followed to prepare blank was same as TVN but only the exception was that 2 ml of the sample was not taken to outer chamber of the Conway dish.
Calculation: Amount of TVN / TMA (mg N / 100g of fish muscle) = (Burette reading- Blank reading) × 0.2 x Volume of extract × 100 Wt. of the sample × Volume of the extract taken 3.8 Analytical Methods for the Determination of Biochemical Composition: 3.8.1 Determination of Moisture content At first two dried porcelain basins of known weight were taken with minced sample in each basin. The weight of the basins with fish were taken in a chemical balance and placed in an oven at about 105ºc for complete evaporation of moisture. After 1 day the basins were transferred into desiccators, cooled and weighed. This process was repeated until a constant weight was obtained. It usually requires 2-3 days for complete drying of dried fishes. The difference in the initial weight and the dried constant weight of the sample gives the moisture content. Percentage of moisture was calculated by the following equation: Wt. of initial sample − Constant wt. of the dried sample × 100 % of moisture= Wt. of the sample taken 3.8.2 Determination of Ash content At first two dried porcelain crucibles of known weight were taken with minced sample in each crucible. About 2 g of sample was weighed in a porcelain crucible. Then the sample was allowed to burn over a flame until it charred and then placed in a muffle furnace at 550ºc - 600ºc temperature for complete combustion. When the material become white residue was cooled weighed. Percentage of ash was calculated by the following equation:
Initial wt. – Final wt. × 100 % of Ash = Wt. of sample taken 3.8.3 Determination of Protein content By “Micro-Kjeldhal” method the crude protein of the dried fish was determined. The principle of Micro-Kjeldhal method for the determination of crude protein is based on the conversion of nitrogen of protein into NH4SO4 when digested with H2SO4 which on distillation with excess of sodium hydroxide liberates ammonia which is than absorbed in boric acid solution with indicator. By titration with (0.01N) HCl solution the amount of nitrogen absorbed in boric acid is determined directly. Procedure: At first about 1g of minced sample in a filter paper was weighed and transferred to the digestion apparatus flask. It was digested with 25 ml. H2SO4 and 1 g Catalyst mixture. In the blank only filter paper was digested similarly. The digestion was done in duplicate for each sample and continued heating until the acid become clear. The digested product of each flask was then 100 ml. in100ml. Volumetric to a Micro-Kjeldhal distillation apparatus followed by 10ml. of 30% Noah which was added slowly and carefully. The distillation was continued for a fixed period and the distillate was collected in 10 ml. of 2% Boric acid solution in3 a 100 ml. conical flask with addition of 4 drops of mix indicator. It was then titrated against (0.01N) HCl solution. Simultaneously a blank titration was also carried out. The percentage of nitrogen in the dried sample was calculated by the following equation:
(S-B) × strength of (0.01N) HCl × 14 × vol. made up to digest (100) × 100 % of N2 = Wt. of sample taken × aliquot the digest take × 1000 Where,S = Final titration reading B = Initial titration reading
The percentage of protein in the dried sample was calculated by multiplying an empirical factor of 6.25 for fish. 3.8.4 Determination of Lipid content At first 5g of dried fish sample was taken in a mortar and homogenized. An adequate amount of sands were added and grained gently by a pestle. 1.0 ml of chloroform-methanol (2:1) mixture was added into the above sample and homogenized properly. Then filtered through a filter paper (11 cm) and was collected into a pre-weighed test tube. Add 1 ml 4% CaCl 2 solution and kept it over night. From the upper portion of the test tube separated the supernatant. All the test tubes were kept in a beaker in an oven at 60ºc for about 2-3 days. Then the test tubes were reweighed The dried sample left after moisture determination was finely ground and about 0.5g were taken in a mortar and macerated with fine sand. These were then flittered with chloroform methanol and 1ml of CaCl2 up to 10ml in weighted test tubes. The test tubes were then kept over night and the supernatants were removed. All the test tubes were kept in a beaker in an oven at 60ºc for about 2-3 days. Then the test tubes were reweighed. The percentage of lipid content was calculated by the following equation:
% of fat =
Final wt. of test tube – Initial wt. of test tube × 100 Wt. of sample taken
Determination of salt content: For the determination of salt content in the brine fish sample, the fish was macerated in a mortar with a pestle to make a homogenous mixture. Then about 5gms of minced fish were transferred to a 250 cc conical flask. About 50 cc of distilled water was poured in to the flask and the mixture was accurately shaken. The flask with sample were kept overnight at 10°C. The content was then made into volume 100 cc in a volumetric flask; filtered and salt content in the filtrate was
determined titrametrically against standard silver nitrate solution using potassium chromate as indicator. The percentage of salt content was calculated by the following equation: 0.005265 × 100 × 100 % Salt content =
Vol. of sample × vol. of solution taken
× Burette reading
Chapter 4 RESULTS AND DISCUSSION 4.1 Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) is the indicator of fish spoilage. During our investigation the average TVN found in room temperature 19.6 (TVN mg-N / 100g of fish sample) and in freezing condition 14.7(TVN mg-N / 100g of fish sample)( fig: 1). Table 1: Determination of Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
At ambient R1 Temperature R2 At 4-5°C F1 Temperature F2 Blank
of Amount N/70H 2SO4 (ml) 2.9 2.9 2.5 2.6 1.7
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of (ml) sample 2.9
16.8
2.65
13.3
Table 2: Determination of Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
of Amount N/70H 2SO4 (ml)
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of (ml) sample
At ambient R1 Temperature R2 At 4-5°C F1 Temperature F2 Blank
3.0 2.9 2.7 2.7 1.7
2.95
17.5
2.7
14.0
Table 3: Determination of Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
of Amount N/70H 2SO4 (ml)
At ambient R1 Temperature R2 At 4-5°C F1 Temperature F2 Blank
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of (ml) sample
3.1 3.1 2.9 2.8 1.7
3.1
19.6
2.85
14.7
Table 4: Total volatile nitrogen (TVN mg –N / 100 g of fish muscle) of Harpodon nehereus at ambient temperature and at 4-5°C temperature Storage period (in days) TVN at ambient temperature TVN at 4-5°C temperature
3
15
30
16.8 13.3
17.5 14
19.6 14.7
Figure 1: Values of TVN at ambient temperature and at 4-5°C in storage period (in days) are shown in graphical representation
TVN at 4-5째C temperature TVN at ambient temperature
Series1 Series2
(in days)
Series3
Storage period
0
10
20
30
40
50
60
4.2 Tri-methyl Amine (TMA mg-N / 100g of fish sample) In freezing condition the average TMA was 4.2 (TMA mg-N / 100g of fish sample) and in the ambient condition 6.06(TMA mg-N / 100g of fish sample) (fig: 2)
Table 5: Determination of Tri-methyl Amine (TMA mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
At ambient R1 Temperature R2 At 4-5째C F1 Temperature F2 Blank
of Amount N/70H 2SO4 (ml) 2.1 2.0 2.0 1.9 1.7
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of (ml) sample 2.05
4.9
1.95
3.5
Table 6: Determination of Tri-methyl Amine (TMA mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
of Amount N/70H 2SO4
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of
At ambient R1 Temperature R2 At 4-5°C F1 Temperature F2 Blank
(ml)
(ml)
sample
2.1 2.2 1.9 2.1 1.7
2.15
6.3
2.0
4.2
Table 7: Determination of Tri-methyl Amine (TMA mg-N / 100g of fish sample) of Harpodon nehereus
Sample
Number Sample
of Amount N/70H 2SO4 (ml)
At ambient R1 Temperature R2 At 4-5°C F1 Temperature F2 Blank
2.2 2.2 2.0 2.1 1.7
of Mean Amount Amount of TVN of N/70 H 2SO4 mg-N/100 g of (ml) sample 2.2
7.0
2.05
4.9
Table 8: Trim ethylamine (TMA mg/ 100 g of fish muscle) of Harpodon nehereus at ambient Temperature and at 4-5°C temperature Storage period (in days) TMA at ambient temperature TMA at 4-5°C temperature
3
15
30
4.9 3.5
6.3 4.2
7.0 4.9
Figure 2: Graphical representation of Trim ethylamine (TMA mg/ 100 g of fish muscle) of Harpodon nehereus at ambient Temperature and at 4-5°C temperature
TMA at 4-5째C temperature TMA at ambient temperature
Series1 Series2 Series3
(in days) Storage period
0
10
20
30
40
50
4.3 Proximate composition The average proximate composition are shown in the pie diagram (Figure 3,4) Table 9: Determination of Lipid content of Harpodon nehereus Sample
Weight of Weight of Calculated the test the test weight tube tube+ sample sample (g) (g) (g)
At ambient 18.24 Temperature At 4-5째C 18.36 Temperature
Weight of Weight of Lipid (%) the test lipid tube+ lipid (g)
(g)
18.74
0.5
18.27
0.03
6
18.86
0.5
18.38
0.02
4
Table 10: Determination of Lipid content of Harpodon nehereus Sample
At
Weight of Weight of Calculated the test the test weight tube tube+ sample sample (g) (g) (g)
ambient 18.24
18.74
0.5
Weight of Weight of Lipid the test lipid tube+ lipid (g)
(g)
(%)
18.26
0.02
4
Temperature At 4-5째C 18.36 Temperature
18.86
0.5
18.38
0.02
4
Table11: Average Lipid content of Harpodon nehereus Sample
Value of table 8
Value of table 9
At ambient Temperature At 4-5째C Temperature
(%) 6 4
(%) 4 4
Average Lipid content (%) 5 4
Figure 3: Average Lipid content of Harpodon nehereus in graphical representation
6 5 4 3 Of ambient Temperature
2
Of 4-5째C Temperature
1 0 (%) Value of table 8 Value of table 9
Average Lipid content
Table 12: Determination of moisture content of Harpodon nehereus Sample
Weight of the Weight of Sample Petri dish Petri dish + weight sample
Weight after Percentage 1 day in oven
(g)
(g)
(g)
(g)
(%)
At ambient 23.38 Temperature At 4-5째C 26.25 Temperature
26.38
3.0
26.06
10.67
29.25
3.0
28.99
8.67
Table 13: Determination of moisture content of Harpodon nehereus Sample
Weight of the Weight of Sample Petri dish Petri dish + weight sample
Weight after Percentage 1 day in oven
(g) At ambient 23.37 Temperature At 4-5째C 26.26 Temperature
(g)
(g)
(g)
(%)
25.37
2.0
25.10
13.5
28.26
2.0
27.99
13.5
Table 14: Average moisture content of Harpodon nehereus Sample
Value of table 11
Value of table 12
At ambient Temperature At 4-5째C Temperature
(%) 10.67 8.67
(%) 13.5 13.5
Average Lipid content (%) 12.09 11.09
Table 15: Determination of average ash content of Harpodon nehereus Sample
Weight of Weight of Weight of Final Weight of Ash crucible crucible sample weight of ash content +sample crucible + % ash (g) (g) (g) (g) (g) At ambient 19.53 21.53 2.0 19.66 0.13 6.5 Temperature 20.53 2.0 18.69 0.16 8 At 4-5째C 18.53 Temperature Figure No.3 Biochemical composition of Harpodon nehereus at ambient temperature
6.5
5
12.09
Ptotein Moisture Ash Fat 76.41
Figure No.4 Biochemical composition of Harpodon nehereus at 4-5째C temperature
6.5
5
12.09
Ptotein Moisture Ash Fat 76.41
Chapter 5 DISCUSSION 5.1 Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) Total Volatile Nitrogen (TVN mg-N / 100g of fish sample) is the main indicator of fish spoilage. TVN become increased at the time period increased .At the beginning the TVN value was remained same. In the Freezing condition the bacterial activities retired so production volatile nitrogen containing is stopped. While in the ambient temperature the condition is
favorable for bacterial growth and increased the production of Total Volatile Nitrogen. Muslemuddin et al,.(1978), also reported that thought the production of TVN increased with the progress of storage time in ice yet it did not show the rise with time due to leaching action of melt water. However, ambient (at 300c) the rate of formation of TVN must have superceded the leaching action, thus showing an increase of the TVN values with the length of soaking time. The above findings lead to the suggestion that during spoilage changes studies in lower temperatures, (here 40-50 C) the use of chemical parameter (determination of TVN value) does not give any clear index of Qualitative Change. In that case, the sensory method should be followed very carefully. The acceptable ranges of TVN value are our study has been found to 38mg/100grm. of fish mussel in case of TVN Value the upper limit for acceptability has been drawn at 30 mg/100grm. of fish mussel the upper limit has been suggested by, Yamamura(1933) And Ahmed el al,. (1981) So, our actual range was with the range of weirzhehowski (1956) who suggested a range of 30mg-40mg/100gms. of fish mussel a acceptable limit. Figure No.1 Biochemical composition of Harpodon nehereus at ambient temperature
6.5
5
12.09
Ptotein Moisture Ash Fat 76.41
Figure No.2 Biochemical composition of Harpodon nehereus at 4-5째C temperature
4
8 11.0 9
Ptotei n Moisture Ash Fat
76.9 1
Figure 3 Values of TVN at ambient temperature and at 4-5째C in storage period (in days)
TVN at 4-5째C temperature
13.3
TVN at ambient temperature
14
16.8
14.7
17.5
19.6
Series1 Series2 Series3
Storage period (in days)
3 0
15 10
30 20
30
40
50
60
Figure 4 Values of TMA at ambient temperature and at 4-5째C in storage period (in days)
TMA at 4-5째C temperature
3.54.2 4.9
TMA at ambient temperature
4.9 6.3
7
Series1 Series2 Series3
Storage period (in days)
0
3
15 10
30 20
30
40
50
Plate 1. Raw dried Bombay duck (Harpodon nehereus Hamilton-Buchanan, 1822)
Plate 2. Determination of Sample pH Plate 3
Plate 4
Plate 3 & 4: Sample 1 stored in Freezing temperature 40-50C and sample 2 stored in room temperature (Âą300C) Plate 5
Plate 6
Plate 5 & 6: Sample for determination of total volatile nitrogen (TVN mg-N / 100g o fish sample)
Plate 7: Photography showing the sample stored in muffle furnace for determination of ash
5.2 Tri methylamine (TMA mg-N / 100g of fish sample) Plate 8: Photography showing the sample stored in incubator for determination of moisture Trim ethyl amine (TMA) is produced by many spoilage micro-organisms from a compound known as trim ethylamine oxide (TMAO).Trim ethyl amine (TMA) was determined at different day interval (3,5,30 day) the average TMA was at room temperature and at freezing condition the TMA was 3.16 (Fig:2) Trim ethyl amine (TMA) normally found in the freshwater fish spp. But found in the marine fish spp. At a level related to the salinity of the habitat. Dried fisheries product may have fewer microorganisms to produce trim ethylamine oxide (TMAO). But for long-term preservation these products may infected by microorganism which could retire by short-term preservation method like freezing. In our investigation the average TMA was 19.63.at room temperature and 14.7 at freezing condition. This due to less spoilage of the fish muscle due to fewer microorganisms I.J.Clucas (1982). Ice has a preservative action on the fish product. 5.3 Proximate composition The result of the proximate composition the raw Harpodon nehereus contain in room temperature was Moisture:12.09% Ash
:6.3%
Protein :76.61% Fat
:5% And the freezing condition the proximate of raw Harpodon nehereus was
Moisture:11.09% Ash
:8 %
Protein :76.91% Fat
:4%
Kuda et el.,(1962) studies the proximate composition in large quantity of both fresh and dried fish of this region and found the following ranges. Proximate composition Moisture Ash Protein Fat
Fresh fish 75.85-82.45% 0.77-1.66% 12.26-20.01% 0.38-4.01%
Dry fish 15.93-20.42% 4.77-10.48% 63.25-72.78% 1.81-5.38%
Kamaluddin et al.,(1977) published data on proximate composition of large number of fish of this region. They obtain: Moisture:70.00% Ash
:01.50%
Protein :16.50 % Fat
:9.50% In case of adult Puntius stigma Latifer et al.,(1981),reported that
Moisture:83.11% Ash
:13.97%
Protein :19.28 % Fat
:3.14% The result of the proximate composition of, dried Harpodon nehereus
collected in the month of June and July 2006.
That is more or less has got
similarities with the finding of the above scientists like (Kuda et al; 1962). During preservation ice has a positive impact on the quality thus the protein quality and mineral composition become intact. Room temperature storage may be has a negative impact on the product quality thus the protein composition might lower down. RECOMMENDATION
1. During the current study the effect freezing on dried fish quality was evaluated. Further studies should be conducted on other method of preservation. 2. More research is needed to evaluate the involvement different chemical associated with the spoilage. 3. Current study is totally laboratory (off station) based, so further fields studies are needed to clarify the actual effect of freezing preservation.
CONCLUSION Dried Loitta fish Harpodon nehereus of Bangladesh has a very favorable flavor and taste of its own. This species has a important exploitable value. This fish export in abroad in dried condition .So the qualitative and quantitative value must be maintained during preservation. Blow fly infestation and different microorganism might infected the protein quality of the dried product. Our present investigation has focus on the qualitative and quantitative changed in the present marketing condition and solve the problem. Short-term preservation method might help to solve the present problem. REFERENCES Ahmed, M. 1991. A model to determine benefits obtainable from the management of riverine fisheries of Bangladesh. ICLARM Tech. Rep. 28,133p. A.O.A.C, 1965. “Official method of analysis.� Association of official agricultural chemists. 10 th Ed. Washington, D.C Bargstorm, G. 1961. Fish as Food. Academic press, Newyork, London, Toronto, Sydney, Sanfrancisco. Vol 1:145-152: 613. Boyce, J.K. 1991. Birth of a mega project: the political economy of flood control in Bangladesh. Journal of Social Study 52 (April): 1-23.
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deterioration Hilsa fish during storage. Proc. 3 rd Ann. Bang. Science Conf; Abst. No. Peryam, D.R and Pilgrim F.I. 1957, Food technol. Champaign 11: 9-14.
Rahman, M.A., Gheyasuddin, S. and Majid, M. A. ,1978. Effects of drying on the composition and the quality of Rhu Fish. Bangladesh J. Agri. Sci. 5 (1), 113-118. Rubbi, S.F., Rahman, M.M., Khan, A.R., Jahan, S.S. and Begum, M. 1987. Proximate composition of some commercial species of fresh water fish. Bang. J. Sci. Ros. %(1): 1-20. Shafi, M.O. and Quddus, M.M.A. 1982. Bangladesher Matsha Shampad, Bangla Academy. P. 174-175. Thilsted, S. and Hassan, N. 1993. A comparison of the nutritional value of indigenous fish in Bangladesh-the contribution to dietary intake of essential nutrients. The XV international Congress of Nutrition, Adelide, Australia, 12p. Tsai, Chu-fa and Youssouf, M.A. 1997. Open water Fisheries of Bangladesh, The University Press Ltd. P. 95. Von Loesecke, H.W. 1955. Drying and Dehydration of foods. Reinhold Publishing Corporation, Newyork, London: Chapman and Hall (Ltd.) P. 164.
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