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Fruit and Vegetable Phytochemicals Elhadi M. Yahia
High Pressure Processing of Fruit and Vegetable Products
Contemporary Food Engineering
Series Editor
Professor Da-Wen Sun, Director
Food Refrigeration & Computerized Food Technology
National University of Ireland, Dublin (University College Dublin) Dublin, Ireland
http://www.ucd.ie/sun/
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High Pressure Processing of Fruit and Vegetable Products
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Netsanet
Jaroslav Dobiáš and Lukáš Vápenka
Concepción Sánchez-Moreno and Begoña De Ancos
Chapter 9 High-Pressure Processing Combined with Heat for Fruit and Vegetable Preservation ..............................................................
Ariette Matser and Martijntje Vollebregt
Chapter 10 Examples of Commercial Fruit and Vegetable Juices and Smoothies Cold Pasteurized by High Pressure .........................
Milan Houska and Petr Pravda
Chapter 11 Regulatory Aspects of High-Pressure Processed Foods in North America, Europe, Asia, New Zealand, and Australia ......................
Tatiana Koutchma and Keith Warriner
Chapter 12 Conclusions and Final Remarks .......................................................
Milan Houska and Filipa Vinagre Marques da Silva
Series Preface
CONTEMPORARY FOOD ENGINEERING
Food engineering is the multidisciplinary field of applied physical sciences combined with the knowledge of product properties. Food engineers provide the technological knowledge transfer essential to the cost-effective production and commercialization of food products and services. In particular, food engineers develop and design processes and equipment to convert raw agricultural materials and ingredients into safe, convenient, and nutritious consumer food products. However, food engineering topics are continuously undergoing changes to meet diverse consumer demands, and the subject is being rapidly developed to reflect market needs.
In the development of food engineering, one of the many challenges is to employ modern tools and knowledge, such as computational materials, science, and nanotechnology, to develop new products and processes. Simultaneously, food quality improvement, safety, and security continue to be critical issues in food engineering studies. New packaging materials and techniques are being developed to provide more protection to foods, and novel preservation technologies are emerging to enhance food security and defense. Additionally, process control and automation regularly appear among the top priorities identified in food engineering. Advanced monitoring and control systems are developed to facilitate automation and flexible food manufacturing processes. Furthermore, energy-saving and the minimization of environmental problems continue to be important food engineering issues, and significant progress is being made in waste management, efficient utilization of energy, and reduction of effluents and emissions in food production.
The Contemporary Food Engineering Series, consisting of edited books, attempts to address some of the recent developments in food engineering. The series covers advances in classical unit operations in engineering applied to food manufacturing as well as topics such as progress in the transport and storage of liquid and solid foods; heating, chilling, and freezing of foods; mass transfer in foods; chemical and biochemical aspects of food engineering and the use of kinetic analysis; dehydration, thermal processing, nonthermal processing, extrusion, liquid food concentration, membrane processes, and applications of membranes in food processing; shelf-life and electronic indicators in inventory management; sustainable technologies in food processing; and packaging, cleaning, and sanitation. These books are aimed at professional food scientists, academics researching food engineering problems, and graduate-level students.
The editors of these books are leading engineers and scientists from different parts of the world. All the editors were asked to present their books to address the market’s needs and pinpoint cutting-edge technologies in food engineering.
All contributions are written by internationally renowned experts who have both academic and professional credentials. All authors have attempted to provide critical, comprehensive, and readily accessible information on the art and science of a relevant topic in each chapter, with reference lists for further information. Therefore, each book can serve as an essential reference source to students and researchers in universities and research institutions.
Da-Wen Sun Series Editor
Series Editor
Prof. Da-Wen Sun, born in southern China, is a global authority in food engineering research and education; he is a member of the Royal Irish Academy (RIA), which is the highest academic honor in Ireland; he is also a member of Academia Europaea (The Academy of Europe), one of the most prestigious academies in the world, a fellow of the International Academy of Food Science and Technology, and a fellow of International Academy of Agricultural and Biosystems Engineering. He is also the founder and editorin-chief of Food and Bioprocess Technology, one of the most prestigious food science and technology journals; the series editor of “Contemporary Food Engineering” book series with already about 50 volumes published; and the founder and president of the International Academy of Agricultural and Biosystems Engineering (iAABE). In addition, he served as the president of the International Commission of Agricultural and Biosystems Engineering (CIGR), the world’s largest organization in the field, in 2013–2014, where is now an honorary president. He has contributed significantly to the field of food engineering as a researcher, academic authority, and educator.
His main research activities include cooling, drying, and refrigeration processes and systems, quality and safety of food products, bioprocess simulation and optimization, and computer vision/image processing and hyperspectral imaging technologies. His many scholarly works have become standard reference materials for researchers, especially in the areas of computer vision, computational fluid dynamics modeling, vacuum cooling, and related subjects. Results of his work have been published in over 800 papers including more than 400 peer-reviewed journal papers (Web of Science h-index = 79); among them, 31 papers have been selected by Thomson Reuters’s Essential Science IndicatorsSM as highly cited papers, ranking him no. 1 in the world in agricultural sciences (December 2015). He has also edited 14 authoritative books. According to Thomson Scientific’s Essential Science IndicatorsSM, based on data derived over a period of ten years from Web of Science, there are about 4,500 scientists who are among the top one percent of the most cited scientists in the category of Agriculture Sciences, and in the last few years, Professor Sun has consistently been ranked among the very top 10 scientists in the world (he was at the 9th position in January 2017), and has been named Highly Cited Researcher in 2015 and 2016 by Thomson Reuters.
He received a first-class BSc honors and MSc in mechanical engineering and a PhD in chemical engineering in China before working in various universities in Europe. He became the first Chinese national to be permanently employed in an Irish university when he was appointed college lecturer at the National University of Ireland, Dublin (University College Dublin, UCD), in 1995, and was then progressively promoted in the shortest possible time to senior lecturer, associate professor, and full professor. Dr. Sun is now a professor of food and biosystems engineering
and the director of the UCD Food Refrigeration and Computerized Food Technology Research Group.
As a leading educator in food engineering, Prof. Sun has trained many PhD students who have made their own contributions to the industry and academia. He has also frequently delivered lectures on advances in food engineering at academic institutions worldwide, and delivered keynote speeches at international conferences. As a recognized authority in food engineering, he has been conferred adjunct/visiting/ consulting professorships from 10 top universities in China, including Zhejiang University, Shanghai Jiaotong University, Harbin Institute of Technology, China Agricultural University, South China University of Technology, and Jiangnan University. In recognition of his significant contribution to food engineering worldwide and for his outstanding leadership in the field, the International Commission of Agricultural and Biosystems Engineering (CIGR) awarded him the “CIGR Merit Award” in 2000, and again in 2006, and the Institution of Mechanical Engineers based in the United Kingdom named him “Food Engineer of the Year 2004.” In 2008, he was awarded the “CIGR Recognition Award” in honor of his distinguished achievements as one of the top 1% among agricultural engineering scientists in the world. In 2007, he was presented with the only “AFST(I) Fellow Award” given in that year by the Association of Food Scientists and Technologists (India), and in 2010, he was presented with the “CIGR Fellow Award”; the title of Fellow is the highest honor at CIGR and is conferred to individuals who have made sustained, outstanding contributions worldwide. In March 2013, he was presented with the “You Bring Charm to the World Award” by Hong Kong–based Phoenix Satellite Television with other award recipients including the 2012 Nobel Laureate in Literature, and the Chinese Astronaut Team for Shenzhou IX Spaceship. In July 2013, he received the “Frozen Food Foundation Freezing Research Award” from the International Association for Food Protection (IAFP) for his significant contributions to enhancing the field of food-freezing technologies. This is the first time that this prestigious award was presented to a scientist outside the United States. In June 2015 he was presented with the “IAEF Lifetime Achievement Award.” This IAEF (International Association of Engineering and Food) award highlights the lifetime contribution of a prominent engineer in the field of food.
Editors
Dr. Milan Houska, born June 16, 1952 in Prague.
1971–1976: MSc degree in process engineering and design of chemical and food machinery
1980: PhD degree, thesis “Engineering Rheology of Thixotropic Fluids”
1980–1985: Scientific worker of Department of Physical Properties of Foods at Food Research Institute Prague (FRIP)
1985–1998: Head of Department of Physical Backgrounds of Food Processing, FRIP
1999–2015: Head of Department of Food Engineering, FRIP
2015–2017: Senior researcher
June 2017–now: Vice-director for research at FRIP
He earned his PhD degree after 3 years of studying at Department of Process Engineering at Faculty of Mechanical Engineering of the Czech Technical University in Prague. The title of the PhD thesis was “Engineering Rheology of Thixotropic Fluids.” After finishing PhD studies, he started to work at FRIP at the Department of Physical Properties of Foods, where studies of texture and mechanical and thermal properties were conducted. After several years of the work in this department, he became a head of this department. After joining with the Department of Heat Processing of Foods, he started to be a leader of the joint departments with the title Department of Food Engineering.
Research activities
• Rheological and mechanical properties of foods
• Food properties database
• Modelling of thermal processes during production
• Distribution and retail and quantitative analysis of risk of growth and survival of pathogenic and spoilage microorganisms
• Food color (with coworkers)
• Influence of high pressure on foods
• Vacuum cooling of liquid and solid foods
• Enhanced speed thawing of foods
Main projects
• Coordinator of the project “Aseptic cooker AV-630.”
• Coworker at the project “Aseptic filling machine ASP200/360.”
• Coordinator of the previous project granted by the National Agency for Agricultural.
• Research “Development of equipment and research of influence of high pressure on nonthermal processing of foods,” successfully finished in 1998.
• Coordinator of the project dealing with processing of foods that decrease the allergenic activities of apple, carrot, and celery juices.
• Coordinator of the project dealing with physical methods of treatment of wine grapes to contain more resveratrol content (UV treatment, ozonized water treatment, and storage).
• He is an active editor of the Journal of Food Engineering, Elsevier.
Dr. Filipa Vinagre Marques da Silva’s research activity and interests are in Food Process Engineering, in particular studying the effects of new food preservation technologies such as high-pressure processing, on food safety and shelf-life, and the design of proper pasteurization processes. Her expertise in microbiology and enzymes are helpful for studying the effect of emerging food pasteurization technologies on food spoilage microbes/enzymes. The production of plant extracts and the determination of their biological activity such as antibacterial, antifungal, and insecticidal activities, is another area of research.
Contributors
Francisco Purroy Balda Hiperbaric, S.A. Burgos, Spain
Roman Buckow
CSIRO Agriculture and Food Werribee, Victoria, Australia
Begoña De Ancos Institute of Food Science, Technology and Nutrition—ICTAN
Spanish National Research Council—CSIC Madrid, Spain
Jaroslav Dobiá š Department of Food Preservation University of Chemistry and Technology Prague, Czech Republic
Evelyn Department of Chemical Engineering University of Riau Pekanbaru, Indonesia
Milan Houska Food Research Institute Prague, Czech Republic
Tatiana Koutchma Agriculture and Agri-Food Canada Guelph, Ontario, Canada
Pui Yee Lee Department of Food Science University of Otago Dunedin, New Zealand
Ariette Matser Wageningen UR Food & Biobased Research Wageningen, the Netherlands
Indrawati Oey Department of Food Science University of Otago Dunedin, New Zealand
Petr Pravda Kofola Joint Stock Company Ostrava-Poruba, Czech Republic
ConcepciÓn Sánchez-Moreno Institute of Food Science, Technology and Nutrition—ICTAN Spanish National Research Council—CSIC Madrid, Spain
Filipa Vinagre Marques da Silva Chemical and Materials Engineering Department University of Auckland Auckland, New Zealand
Netsanet Shiferaw Terefe
CSIRO Agriculture and Food Werribee, Victoria, Australia
Jan T ř íska
Global Change Research Institute CAS Brno, Czech Republic
Lukáš Vápenka
Department of Food Preservation University of Chemistry and Technology Prague, Czech Republic
Martijntje Vollebregt
Wageningen UR Food & Biobased Research Wageningen, the Netherlands
Keith Warriner
University of Guelph Guelph, Ontario, Canada
1 Introduction to High-Pressure Processing of Fruit and Vegetable Products
Milan Houska and Filipa Vinagre Marques da Silva
High-pressure processing (HPP) is a cold pasteurization technology by which products, already sealed in their final package, are introduced to a vessel and subjected to a high level of isostatic pressure (300–600 MPa). As pressure is commonly transmitted by the water contained inside the HPP chamber, the technology is also referred to as high hydrostatic pressure. Both commercial HPP units with high capacity and several food products, namely of fruit origin, are marketed successfully around the world. Chapter 5 is devoted to industrial equipment available whereas Chapter 10 deals with examples of commercial fruit and vegetable products. Chapter 4 is dedicated to packaging, as prior packaging of food before HPP is mandatory in this technology.
High-pressure treatment of fruit and vegetable products opens the gate to nearly fresh products as regards the sensorial and nutritional quality of original raw materials. It has a great commercial importance and it enables consumers to find a relatively stable and safe source of nutrients, vitamins, minerals, and health effective components. Such components can play an important role as a preventive tool against the start of illnesses, namely in the elderly. It is well known that a preventive health effective diet is cheaper than “solving the consequences” by pharmaceuticals. Many fruits and vegetables are eaten raw and thus present a higher content of vitamins and other thermolabile constituents as opposed to foods that are cooked before consumption. The conventional thermal pasteurization/sterilization applied to fruit and vegetable juices not only decreases the “fresh notes” of the raw fruits/ vegetables, but also generates new “cooked notes” flavors (Silva et al., 2000), often undesirable. In addition, the fruit and vegetable color, antioxidant properties, and other quality parameters can also be negatively affected by thermal treatments, as opposed to HPP (Patras et al., 2009; Silva et al., 1999; Sulaiman et al., 2017). Thus, the HPP technology allows nonthermal pasteurization of fruit juices and other beverages, namely sodas and alcoholic (e.g., beer and wine), better retaining its original organoleptic and nutritive properties (Milani and Silva, 2016) with extended shelflife and possibly with fewer/no chemical preservatives (van Wyk and Silva, 2017). The effects of HPP technology on the quality of fruit and vegetable products, namely
nutrients and stability, health active components, and sensory aspects, were reviewed in Chapters 6 through 8.
The regulatory aspects for high-pressure treated fruit and vegetable products in different regions of the world (Europe, the United States, Asia, and Australia) are also an important topic dealt with in Chapter 3 of the book. Effects of HPP and HPP + heat on key spoilage/pathogenic microorganisms including the resistant spore form and fruit/vegetable endogenous enzymes were covered in detail in Chapters 2 and 3. Chapter 9 of this book deals with heat-assisted HPP and its effect on quality.
REFERENCES
Milani, E.A., Silva, F.V.M. 2016. Nonthermal pasteurisation of beer by high pressure processing: Modelling the inactivation of Saccharomyces cerevisiae ascospores in different alcohol beers. High Pressure Research 36(4): 595–609.
Patras, A., Brunton, N.P., Da Pieve, S., Butler, F. 2009. Impact of high pressure processing on total antioxidant activity, phenolic, ascorbic acid, anthocyanin content and color of strawberry and blackberry purees. Innovative Food Science and Emerging Technologies 10(3): 308–313.
Silva, F.M., Silva, C.L.M. 1999. Colour changes in thermally processed cupuaçu (Theobroma grandiflorum) purée: Critical times and kinetics modelling. International Journal of Food Science and Technology 34(1): 87–94.
Silva, F.M., Sims, C., Balaban, M.O., Silva, C.L.M., O’Keefe, S. 2000. Kinetics of flavour and aroma changes in thermally processed cupuaçu (Theobroma grandiflorum) pulp. Journal of the Science of Food and Agriculture 80(6): 783–787.
Sulaiman, A., Farid, M., Silva, F.V.M. 2017. Strawberry puree processed by thermal, high pressure or power ultrasound: Process energy requirements and quality modeling during storage. Food Science and Technology International 23(4): 293–309.
van Wyk, S., Silva, F.V.M. 2017. High pressure inactivation of Brettanomyces bruxellensis in red wine. Food Microbiology 63: 199–204.
2 High-Pressure Processing Effect on Microorganisms in Fruit and Vegetable Products
Filipa Vinagre Marques da Silva and Evelyn
2.1 INTRODUCTION
High pressure processing (HPP), also named high hydrostatic pressure, is a modern method of food pasteurization commercially used in many countries. It relies on the application of very high pressures (up to 600 MPa) to the food/beverage to inactivate microorganisms. Since no heat or mild heat is applied, most of the original food sensory, nutrient, and functional properties are retained after processing, and fresh-like fruit and vegetable products with longer shelf life are produced. HPP can damage the microbial cell membrane, which affects its permeability and ion exchange, and denature proteins involved in microbial replication. Examples of commercial HPP processed fruit and vegetable products are citrus/fruit/vegetable juices, fruit jams, jellies and dressings, avocado products and salsas, and vegetable products/meals. After pasteurization, the fruit and vegetable products may contain microorganisms in lower concentrations. Therefore, they are stored cold and distributed at temperatures below 7°C to avoid or retard undesirable microbial growth during storage. The low temperature also inhibits enzymatic or other biochemical spoilage reactions. The microorganisms able to grow under refrigerated conditions, classified as psychrotrophs, are more critical for HPP fruit and vegetable products. Nevertheless, since few studies on psychrotroph’s inactivation by HPP are available, all types of microorganisms were reviewed. Those were bacteria, molds, and yeasts, which can be found in fruit and vegetable products and included spore-formers, non-spore-formers, pathogenic, and spoilage organisms. We are listing different categories of microorganisms covered in the chapter.
2.2 SPOILAGE MICROORGANISMS IN FRUIT AND VEGETABLE PRODUCTS
The highest incidence of rapid spoilage of processed foods is caused by bacteria, followed by yeasts and molds (Sinell, 1980). Parasites (protozoa and worms), natural toxins, viruses, and prions can also be a problem if industry uses contaminated raw materials (FDA, 1992).
2.2.1 Microbial SporeS
Before discussing microbial targets of pasteurization, we must recognize that the spore is the most resistant microbial form. Spore is a highly resistant dehydrated form of dormant cell produced under conditions of environmental stress and as a result of “quorum sensing.” Molds (e.g., Neosartorya fischeri, Byssochlamys nivea), certain yeasts (Saccharomyces cerevisiae), and bacteria (Alicyclobacillus acidoterrestris, Bacillus coagulans, Bacillus subtilis) can produce spores, although yeast spores are not as resistant as bacterial spores. Heat is the most efficient method for spore inactivation and is presently the basis of a huge worldwide industry (Bigelow and Esty, 1920; Gould, 2006). Microbial spores are much more resistant to heat in comparison to their vegetative counterparts, generally being able to survive the pasteurization process. Similarly, spores are much more resistant to HPP than vegetative cells, and usually HPP by itself is insufficient to inactivate spores in foods. Thus, the combination of HPP with moderate heat
(HPP-thermal or high pressure thermal processing—HPTP) is used to inactivate spores. The HPTP requires lower temperatures and/or times than thermal processing alone for the same spore inactivation (Evelyn and Silva, 2015a,b, 2016a,b; Evelyn et al., 2016; Silva et al., 2012). Spore resistance may also be affected by the food environment in which the organism is processed (Evelyn, 2016; Evelyn and Silva, 2015a, 2016b). For instance, spores (and vegetative cells) become more resistant at low water activity (Corry, 1976; Murrel et al., 1966; Silva et al., 1999; Uchida and Silva, 2017). The spore age is another important factor for spore resistance, especially for mold spores, which become more resistant to HPTP with time (Evelyn and Silva, 2017). If, after pasteurization, the storage temperature as well as the food characteristics (pH, water activity, food constituents) are favorable for sufficient time, surviving spores can germinate and grow to attain high numbers (e.g., 10 7/g or mL) and cause food-borne diseases or spoilage. Control of spores during storage of pasteurized foods requires an understanding of both their resistance and outgrowth characteristics.
2.2.2 UndeSirable MicroorganiSMS in FrUit prodUctS
In high-acid and acidified foods, the main pasteurization goal is to avoid spoilage during distribution at room temperature or at refrigerated conditions, rather than avoiding outbreaks of public health concern. High-acid foods include most of the fruits, normally containing high levels of organic acids. The spoilage flora is mainly dependent on pH and soluble solids. The type of organic acids and other constituents of these foods such as polyphenols might also affect the potential spoilage microorganisms. Given the high acid content of this class of foods (pH < 4.6), the bacterial pathogens (vegetative and spore cells) including the deadly spore-forming Clostridium botulinum are not able to grow. It is generally assumed that the higher the acidity of the food, the less probable the germination and growth of bacterial spores, a pH < 4.6 being accepted as safe in terms of pathogenic spore-formers. However, various incidents in high-acid foods involving the spore-forming spoilage bacterium Alicyclobacillus acidoterrestris (Cerny et al., 1984; Jay, 2000) have been registered since its optimum growth pH is between 3.5 and 4.5 for the type strain (Pinhatti et al., 1997), and optimum growth temperature is between 35°C and 53°C (Deinhard et al., 1987; Sinigaglia et al., 2003) depending on the strain.
Typical microbes associated with spoilage of high-acid and acidified foods are A. acidoterrestris bacteria, molds such as Byssochlamys nivea and Neosartorya fischeri, yeasts (e.g., Saccharomyces cerevisiae), and lactic acid bacteria (LAB; e.g., Lactobacillus, Leuconostoc). The growth of spoilage spore-forming Bacillus and Clostridium has been reported in less acidic fruit products (3.7 < pH < 4.6) such as tomato purée/juice, mango pulp/nectar, canned pear, and pear juice (Ikeyami et al., 1970; Shridhar and Shankhapal, 1986). In addition, less resistant vegetative microorganisms belonging to the LAB family that do not have the capacity to produce spores can be found in spoiled fruits and vegetables. The Escherichia coli O157:H7 is a vegetative pathogen able to survive and grow at 25°C in acidic environments but not at ≤10°C (Conner et al., 1995). It is known that Salmonella and E. coli 0157:H7 possess
relatively high resistance to acidic environments, being able to survive up to several weeks at pH ≤ 4.6. Although growth is not probable in this acidic environment, their very low infectious dose (10–100 cells) can become a public health concern even in the absence of growth (FDA, 2011).
2.2.3 UndeSirable MicroorganiSMS in Vegetable prodUctS
Most of the bacteria grow best around pH values of 6.5 to 7. As opposed to high acid fruit products, vegetable products and certain fruit juices (e.g., tomato, pear, some tropical juices) have low acidity (pH > 4.6), and therefore vegetative bacterial pathogens (e.g., Salmonella, Escherichia coli), bacterial spores from pathogens (Clostridium botulinum, Bacillus cereus), and bacterial spores from spoilage species (Geobacillus stearothermophilus = Bacillus stearothermophilus) can grow. With respect to temperature, the optimum growth temperature of most bacteria is around 37°C. Thus, cold storage and distribution of low acidity vegetable products is an additional hurdle to controlling the growth of possible survivors (e.g., spore-formers) in the HPP pasteurized vegetable product.
As mentioned, various pathogens can be associated with food-borne diseases and outbreaks from improperly processed/preserved/stored low-acid chilled foods. With respect to public health, the most dangerous spore-formers in low-acid chilled foods are the psychrotrophic nonproteolytic strains of Clostridium botulinum (Gould, 1999; Carlin et al., 2000a). In spite of the low incidence of this intoxication, the mortality rate is high if not treated immediately and properly. These strains of C. botulinum have been implicated in human botulism incidents from the ingestion of not only a few contaminated fish and meat products but also vegetable products (Lindström et al., 2006) such as canned truffle cream/canned asparagus (Therre, 1999), pasteurized vegetables in oil (Aureli et al., 1999), and canned eggplant (Peredkov, 2004). Bacillus cereus is another spore-forming and pathogenic bacterium detected in pasteurized and chilled foods such as cooked rice and other chilled foods containing vegetables (Carlin et al., 2000a,b), since some strains of B. cereus can grow at low temperatures (T < 8°C) (Dufrenne et al., 1994, 1995; García-Armesto and Sutherland, 1997; Choma et al., 2000). There are some nonpathogenic spore-formers including Bacillus and Clostridium spp. (Broda et al., 2000), and molds that can cause significant economic losses to food producers. For example, B. circulans was identified as the major spoilage Bacillus in commercial vegetable purées pasteurized and stored at 4°C (Carlin et al., 2000b). Very limited data on spoilage and HPP/HPTP/thermal resistance of spore-formers are available in the literature.
Other examples of foodborne infections from raw and processed foods include E. coli serotype O157:H7 (verotoxigenic E. coli VTEC; raw fruit juice, lettuce) and Vibrio cholerae (water, ice) (FDA, 1992; WHO, 2002). Psychrotrophic spoilage microbes such as LAB (Lactobacillus spp., Leuconostoc spp., Carnobacterium spp.), molds (Thamnidium spp., Penicillium spp.), and yeasts (Zygosaccharomyces spp.) can also occur in chilled low-acid vegetable products during storage in general due to postprocess contamination. These are very sensitive to HPP.
2.3 PASTEURIZATION
Pasteurization was redefined by the United States Department of Agriculture as “any process, treatment, or combination thereof, that is applied to food to reduce the most resistant microorganism(s) of public health significance to a level that is not likely to present a public health risk under normal conditions of distribution and storage” (NACMCF, 2006). This definition therefore includes nonthermal pasteurization processes such as HPPs, and the effects of HPP on microorganisms and foods are active research topics (Karwe et al., 2014; Norton and Sun, 2008; Rendueles et al., 2011). The efficacy of HPP in terms of microbial spore and endogenous enzyme inactivation in fruit and vegetable products is limited (Evelyn, 2016; Sulaiman and Silva, 2013; Sulaiman et al., 2015, 2017; Van Buggenhout et al., 2006). Thus, simulta neous HPP-thermal (HPTP) processing has been investigated for efficient spore inactivation (Evelyn and Silva, 2015a,b, 2016a; Evelyn et al., 2016). Silva et al. (2012) could successfully reduce the temperature required to inactivate Alicyclobacillus acidoterrestris in orange juice from 85–95°C to 45–65°C when using 600 MPa HPP. Likewise, approximately less than 30°C of temperature resulted in similar N. fischeri and B. nivea ascospore inactivation after 600 MPa HPTP of juice/puree (Evelyn and Silva, 2015b; Evelyn et al., 2016), thus demonstrating the benefit of HPP technology.
2.3.1
Hpp backgroUnd
HPP pasteurized foods were first seen in Japan from the early 1990s (Van Loey et al., 2003), although the extension of food shelf life by HPP was known since 1899 (Hite, 1899). Fruit jams and sauces are examples of the first HPP processed foods, followed by other food products such as guacamole in the United States, fruit juice in France, Mexico, and the UK, and a delicatessen style ham in Spain (Patterson et al., 2006). Since then, HPP has been extended to preserve fruits and vegetables (32%), juices and beverages (11%), meat products (27%), seafood and fish (16%), and other products (14%) (Buckow and Bull, 2012). Approximately 265 industrialscale HPP machines have been produced and installed worldwide for food processing until 2014 with the highest number installed in the North America and Europe (Hiperbaric, 2015). Please consult Chapter 5 for more details.
2.3.2 MecHaniSMS oF Microbial inactiVation dUring Hpp and Hptp
The mechanism of microbial inactivation by high pressure has been thoroughly investigated. Considerable alterations in the cellular structure or physiological functions of microorganisms after exposure to high pressure alone and combined with mild heat result in microbial cell death. This can be seen by observing the structural damage of the cell membrane and envelopes due to membrane phase transition and fluidity changes (Abe, 2013; Rozali, 2015). However, microbial spores are distinguishable from vegetative cells in the mechanism of inactivation by high pressure. Generally, a two-step inactivation process has been widely accepted for spore inactivation: (i) activation of nutrient germinant receptors and the release of dipicolinic
Nonnutrient spore germination
Dominant at 100−200 MPa— retarded up to 600 MPa, T: 30−50°C
Nonphysiological germination
Retarded at 200 MPa— dominant at 400−600 MPa, T < 60°C
Germinant receptors
(GerA homologs)
Release of ions and Ca2+−DPA
Nonphysiological germination p > 600 MPa and T > 60°C
(SpoVA protein unfolding? irre versible or reversible changes in the inner membrane?)
Active Gpr Max 4 log10 (pressure resistant superdormant spores?)
Partial core hydration
Retarded at 400−600 MPa and T < 50°C (Gpr inactivation?)
Cortex hydrolysis and full core hydration
SASP degradation
Inactivation
Rapid inactivation > 7 log10
FIGURE 2.1 Proposed germination and inactivation pathways of Bacillus subtilis, dependent on the applied pressure (P) and temperature (T) conditions by Reineke et al. (2013) (permission from Elsevier).
acid during germination, causing a loss of spore resistance; and (ii) subsequent inactivation by pressure and heat (Black et al., 2005; Georget et al., 2015; Heinz and Knorr, 2002; Mathys et al., 2009; Reineke et al., 2013).
Reineke et al. (2013) suggested that spore germination and inactivation pathways were dependent on the pressure–temperature combinations to explain the mechanism of Bacillus subtilis spore inactivation by HPTP in buffer solution (Figure 2.1). For 100–200 MPa at 30–50°C, physiological spore germination occurs by triggering germinant receptors. Spores are able to degrade small acid-soluble proteins, but only 4 log inactivation was obtained after long pressure dwell times (>1 h). For 400–600 MPa at T < 60°C, and pressure (P) > 600 MPa and temperature (T ) > 60°C, nonphysiological pressure induced germination occurs followed by subsequent inactivation, which is fastest and higher (>7 log inactivation). Nonetheless, more research is needed to elucidate the mechanisms of the spore inactivation in food products.
2.3.3 ModelS For deScribing log Microbial
SUrViVor S aFter Hpp and Hptp
Mathematical models and kinetic parameters for microbial inactivation are important tools to analyze the effectiveness of HPP and HPTP, to design new processes,
B. nivea inactivation in strawberry puree (8.1°Brix) by 600 MPa–75°C
A. acidoterrestris inactivation in apple juice (10°Bri x) by 600 MPa–45°C
N. fischeri inactivation in apple juice (10.6°Brix) by 600 MPa–75°C
S. cerevisiae inactivation in beer (4.8% alc/vol) by 400 MPa–room temperature
A. acidoterrestris inactivation in orange juice (9.2°Bri x) by 600 MPa–65°C
FIGURE 2.2 Bacteria, mold and yeast spore inactivation by HPP and HPTP in fruit products and beer.
and to optimize food safety and quality. These are based on the reduction in the number of microorganisms in response to the application of a lethal effect. Linear and nonlinear models have been commonly used to describe the log survival curves of pathogenic and spoilage bacteria after HPP and HPTP treatments. The nonlinearity of log microbes vs. time is very common, with curves presenting concave upward and tails as shown in examples presented in Figure 2.2 for B. nivea, N. fischeri, S. cerevisiae, and A. acidoterrestris spores submitted to HPP/HPTP. Note that although linearity was registered for A. acidoterrestis spores in apple juice treated at 600 MPa–45°C, the inactivation of spores suspended in orange juice treated at 600 MPa–65°C seemed nonlinear, showing that the same microbe can exhibit linear or nonlinear behavior depending on the processing conditions. The effect of pressure on microbial inactivation is well known and similar to temperature. The higher the HPP pressure, the higher the inactivation. Therefore, the HPTP inactivation studies are often conducted at the maximum pressure allowed by the equipment with measurable changes in the microbial concentration with processing time.
2.3.3.1 Simple First-Order Linear Model
Predictive microbiology began when Bigelow and Esty (1920), Bigelow (1921), and Esty and Meyer (1922) proposed the use of first-order kinetics to model the thermal inactivation of microorganisms in foods. The model describes a linear decrease in the logarithmic cell populations with time, as a constant intensity of pressure and/ or heat is applied. The decimal reduction time DP,T value is the time in minutes at a
certain temperature and pressure necessary to reduce microbial population by 90%, and is calculated from the reciprocal of the slope of the following equation:
The temperature coefficient zT value (°C) is the temperature increase for constant pressure that results in a 10-fold decrease in the D value. This is estimated from the negative reciprocal of the slope of Equation 2.2:
DTref is the D value at the reference temperature Tref (can be any reference temperature, °C); T is the temperature of the isothermal treatment (°C). Similarly, the pressure coefficient z P value (MPa) can also be estimated for a fixed temperature (Equation 2.3, P = HPP pressure in MPa):
With respect to HPP, deviations from the linearity (e.g., tails) can be observed in the survival curves (Evelyn and Silva, 2015a,b, 2016a,b; Evelyn et al., 2016), which can mean that individuals of a microbial population have different resistances.
The biphasic model is a particular case of the first-order kinetics, where the spore survival line presents two rates of microbial inactivation corresponding to two D values.
2.3.3.2 Nonlinear Weibull Model
Due to its simplicity and accuracy, the Weibull distribution (Weibull, 1951) has been used to describe the nonlinear microbial inactivation in various foods. Two mathematical forms of the Weibull model are shown in Equations 2.4 and 2.5. In the Weibull adapted by Peleg and Cole (1998), b (the scale factor) is a rate parameter that is related to the velocity of the inactivation of the microorganism, and n is the survival curve shape factor:
n < 1 and n > 1 correspond to survival curves with concave upward (tailings) and concave downward (shoulders), respectively. If n = 1 t, the Weibull model becomes the simple fi rst-order kinetics.
Van Boekel (2002) presented another form of the Weibull model, in which the Greek letters α and β are the scale and shape parameters, respectively (Equation 2.5). Likewise, the survival curve is concave upward if β < 1 and concave downward if β > 1 and linear if β = 1:
2.4 HPP AND HPTP INACTIVATION OF MICROORGANISMS IN FRUIT PRODUCTS
2.4.1 Spore-For Mer S
In this section, a review of the inactivation results obtained with bacterial and mold spores treated by HPTP and yeast spores treated by HPP in fruit products will be first discussed followed by a review of the models and estimated parameters used to predict microbial spore inactivation by HPP and HPTP in fruit products. Overall, the spores of some strains of B. nivea mold appear to be more resistant to HPTP than N. fischeri mold spores and A. acidoterrestris bacterial spores. The last two seem to have similar resistance. The examples of spore survival lines shown in Figure 2.2 can also confirm this.
2.4.1.1
Bacterial Spores
Table 2.1 shows the log reduction achieved in A. acidoterrestris and Bacillus coagulans bacterial spores suspended in fruit juices, pulps, and concentrates after high pressure in the range of 200 to 621 MPa combined with moderate temperatures of 45–90°C. Tomato juice was HPTP at higher temperature, 105°C. The log reductions for A. acidoterrestris in fruit juice concentrates were minimal due to the high sugar protective effect against pressure and heat. For example, regarding apple juice concentrates processed for 10 min at 621 MPa–90°C, there is no inactivation for 70°Brix as opposed to 5.0 decimal reductions in 35°Brix (Lee et al., 2006). Similarly, in another study with another strain of apple juice/concentrates (35.7°Brix), there is no effect of 200 MPa–50°C process for 10 min vs. 2.0 log reduction in 11.2°Brix juice. The processing temperature has an important role in the spore inactivation. In general, higher reductions in spores were obtained at higher HPP temperatures (60–105°C). For example, HPTP of apple juice containing ATCC 49025 strain processed at 621 MPa–90°C–1 min resulted in 6.0 log reductions (Lee et al., 2002), whereas 600 MPa–45°C–10 min only achieved 1.2 log reductions (Uchida and Silva, 2017) in spite of higher processing time. The effect of strain is also noticeable in Soko łowska et al.’s (2013) results and by comparing between the results of different authors. Likewise, B. coagulans is very resistant requiring also the use of heat for its inactivation in tomato juice/pulp. The use of 105°C resulted in 3.2 log reductions after 0.5 min processing. In general, to achieve 6 log bacterial spore reduction, the maximum pressure and temperature should be used in HPTP processing. To reduce the processing times and increase throughput, higher temperature is recommended.
2.1
TABLE
Bacterial Spore Inactivation in Fruit Products after HPP
et al. 2002
Alicyclobacillus acidoterestris a ATCC 49025, Apple juice
Alicyclobacillus acidoterestris a NFPA1013,
Silva et al. 2012 Alicyclobacillus acidoterestris NZRM 4447
Sokolowska et al. 2013
Alicyclobacillus acidoterestris TO-117/02
Daryaei and Balasubramaniam 2013
Alicyclobacillus acidoterestris TO-29/4/02
Bacillus coagulans 185A
Zimmermann et al. 2013 a Cocktail of strains. nr: not reported.
Bacillus coagulans ATCC 7050
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The fur business of Canada has its beginning when the company trader strikes a bargain with the Eskimo for his season’s catch of the white fox of the arctic and other skins.
The Hudson’s Bay Company has more than two hundred trading posts where Indians, Eskimos, and white trappers exchange furs for goods. Eighteen of the stations lie near or north of the Arctic Circle.
Most of the fine fox skins now marketed in Canada come from animals raised in captivity on fur farms. Occasionally a cat may act as a substitute mother for a litter of fox kittens.
Winnipeg has long been an important city in the Canadian fur trade, and here the world’s greatest fur organization has its headquarters. I refer, of course, to the Hudson’s Bay Company, which for more than two hundred and fifty years has been bartering goods for the furs of British North America. It was founded when the British had scarcely a foothold in Canada, and its operations won for them their dominion over the northwestern part of our continent. In the beginning it was but one of many trading enterprises of the New World. To-day it has adapted itself to the tremendous changes in our civilization and it is bigger, stronger, and richer than ever.
Massachusetts Colony was not fifty years old when the Nonsuch, loaded to the waterline with the first cargo of furs, sailed for England from Hudson Bay. The success of the voyage led the dukes and lords who backed the venture to ask King Charles II for a charter. This was granted in 1670, and thus came into existence, so far as the word of a king could make it so, “The Governor and Company of Adventurers of England Trading into Hudson’s Bay,”
exclusive lords and proprietors of a vast and but vaguely known region extending from Hudson Bay westward, with sole rights to fish, hunt, and trade therein.
It remained for the Company to make good the privileges conferred by the charter and maintain the profits, which at that period sometimes amounted to one hundred per cent. a year. For nearly a century the company’s ships and forts did battle with the armed forces of the French. For another long period its factors and traders had to meet the attacks of rival companies. At times the company was nearly wiped out by the heavy losses it sustained. For almost two centuries it furnished the only government of the Canadian Northwest, and without the use of a standing army it administered a vast region, out of which provinces and territories have since been carved.
The “Company of Adventurers” has now become a fifteen million dollar corporation, paying regularly five per cent. on ten million dollars’ worth of preferred stock. A fleet of river, lake, and ocean steamers has succeeded the Nonsuch. The early trading posts, stocked with crude tools, weapons, and ornaments for the Indians, have been supplemented by a chain of eleven department stores, extending from Winnipeg to Vancouver, and at the same time the number of trading posts exchanging goods for furs is greater than ever. There are about two hundred of these posts, eighteen of which are near or north of the arctic circle. The Company no longer actually governs any territory, and it is selling to settlers the remainder of the seven million acres in the fertile belt it has received from the Dominion since the surrender of its ancient rights in the Northwest.
The story of the Hudson’s Bay Company is a large part of the history of Canada. Many books have been written about it, and countless romances built upon the lives of its men stationed in the wilds. Here at Winnipeg the company has an historical exhibit where one may visualize the life of the trappers and the traders, and gain an idea of the adventures that are still commonplaces in their day’s work. The company museum contains specimen skins of every kind of Canadian fur-bearing animal. The life of the Indians and the
Eskimos is reproduced through the exhibits of their tools, boats, weapons, and housekeeping equipment.
The success of the Hudson’s Bay Company has rested upon its relations with the Indians. The organization is proud of the fact that it has never engaged in wars with the tribes. The business has always been on a voluntary basis, and the Indians have to come to the Company posts of their own free will. At first the traders’ stocks were limited, but through centuries of contact with civilization the wants of the red man have increased and become more varied. They now include nearly everything that a white man would wish if he were living in the woods.
The first skins brought in from Hudson Bay were practically all beavers. This led to the exchange being based on the value of a single beaver skin, or “made beaver.” Sticks, quills, or brass tokens were used, each designating a “made beaver,” or a fraction thereof. The prices of a pound of powder, a gun, or a quart of glass beads were reckoned in “made beaver.”
Early in its history the Company decided that Scotchmen made the best traders and were most successful in dealing with the Indians. Young Scotchmen were usually apprenticed as clerks on five-year contracts, and if successful they might hope to become traders, chief traders, factors, and chief factors. Men in these grades were considered officers of the company and received commissions. Mechanics and men engaged in the transport service were known as “servants” of the company, and the distinction between “servants,” clerks, and officers was almost as marked as in the various military ranks of an army. To-day, Canada is divided into eleven districts, each of which is in charge of a manager, and the old titles are no longer used.
A trader had to be a diplomat to preserve friendly relations with the Indians, an administrator to manage the Company’s valuable properties in his charge, a shrewd bargainer to dispose of his stock on good terms, and at times soldier and explorer besides. The Company’s charter authorized it to apply the laws of England in the territories under its jurisdiction, and its agents frequently had to
administer justice with a stern hand. It early became the inflexible policy to seek out a horse thief, incendiary, or murderer among the Indians and impose punishment, and it was the trader who had to catch his man and sometimes to execute him.
It was the activities of its rivals, and especially of the Northwest Company, that resulted in the establishment of the inland stations of the Hudson’s Bay Company. As long as it had a monopoly, the Company was content to set up posts at points convenient for itself, and let the Indians do all the travelling, sometimes making them go as much as one thousand miles to dispose of their furs. The opposition, however, carried goods to the Indians, and thus penetrated to the far Northwest and the Mackenzie River country. This competition compelled the older organization to extend its posts all over Canada, and finally, in 1821, led to its absorption of the Northwest Company. To-day the chief competitor of the Hudson’s Bay Company is the French firm of Revillon Frères.
The merger with the Northwest Company was preceded by years of violent struggle. The younger concern was the more aggressive. It tried to keep the Indians from selling furs to the Hudson’s Bay traders. Its men destroyed the traps and fish nets, and stole the weapons, ammunition, and furs of their rivals. Neither was above almost any method of tricking the other if thereby furs might be gained. Once some Hudson’s Bay men discovered the tracks of Indians returning from a hunt. They at once gave a great ball, inviting the men of the near by post of the rival company. While they plied their guests with all forms of entertainment, a small party packed four sledges with trade goods and stole off to the Indian camp. The next day the Northwest men heard of the arrival of the Indians and went to them to barter for furs, only to find that all had been sold to the Hudson’s Bay traders. At another time two rival groups of traders met en route to an Indian camp and decided to make a night of it. But the Northwest men kept sober, and, when the Hudson’s Bay men were full of liquor, tied them to their sleds and started their dog teams back on the trail over which they had come. The Northwest traders then went on to the Indians and secured all the furs.
The Hudson’s Bay Company sends all of its raw skins to London, where they are graded and prepared for the auction sales attended by fur buyers from all over the world. It does not sell any in Canada.
Nevertheless, the Dominion is an important fur-making centre. During a recent visit to Quebec, I spent a morning with the manager of a firm which handles millions of dollars’ worth of furs every year. It has its own workshops where the skins are cured and the furs dressed and made into garments. The name of this firm is Holt, Renfrew and Company. Let us go back to Quebec and pay it a visit.
Imagine a quarter of a million dollars’ worth of furs under one roof! Picture to your minds raw skins in bales, just as they were unloaded from an Indian canoe, and then look again and see wraps and coats made from them that would each bring five thousand dollars when sold on Fifth Avenue. If your imagination is vivid enough you may see the American beauties who will wear them and know how the furs will add to the sparkle of their eyes and at the same time lighten the purses of their sweethearts and husbands.
We shall first go to the cold storage rooms. Here are piles of sealskins from our Pribilof Islands. Put one of these furs against your cheek. It feels like velvet. In these rooms are beavers from Labrador, sables from Russia, and squirrels from Siberia. There are scores of fox skins—blue, silver, black, and white. Some of them come from the cold arctic regions and others from fox farms not twenty minutes distant by motor. Take a look at this cloak of silvery gray fur. A year ago the skins from which it was made were on the backs of hair seals swimming in the mouth of the St. Lawrence River.
As we go through the factory, some of the secrets of fur making are whispered to us. For example, this bale contains fifteen hundred skins of the muskrat. The animals which produced them will change their names after a trip to the dyers. They will go into the vats and when they come out they will be Hudson Bay seals, and eventually will find their way into a black coat with a wonderful sheen. Years ago the muskrat skin was despised. Now it is made into coats that, under the trade name of Hudson seal, bring nearly as much as those of real seal.
Here are two Russian sables, little fellows of beautiful fur, that together will form a single neck piece. The undressed skins are worth seven hundred dollars the pair. As we look, the manager shows us two native sables that seem to be quite as fine. He tells us they can be had for eighty-five dollars each, or less than a quarter of the price of the Russian.
The most valuable fur in the world to-day is the sea otter, of which this firm gets only three or four skins in a year. But, in contrast, over there is a whole heap of Labrador otters, beautiful furs, which will wear almost for ever and will look almost as well as the sea otter itself. But you can have your choice of these at forty dollars apiece. They are cheap chiefly because the Labrador skin is not in fashion with women. Fashion in furs is constantly changing. Not many years ago a black fox skin often brought as much as fifteen hundred dollars. To-day, so many are coming from the fur farms that the price has fallen to one hundred and fifty dollars. Scarcity is one of the chief considerations in determining the value of furs, and fashion always counts more than utility. The rich, like the kings of old, demand something that the poor cannot have, and lose their interest in the genuine furs when their imitations have become common and cheap.
The dyer and his art have greatly changed the fur trade. It is he who enables the salesgirl to wear furs that look like those of her customers. For example, here is a coat made of the best beaver. Its price is four hundred dollars, and beside it is another made of dyed rabbit fur, marked one hundred and fifty dollars. It is hard for a novice to tell which is the better. All sorts of new names have been devised by the furriers to popularize dyed skins of humble animals, from house cats to skunks, in order to increase the supply of good-looking and durable furs. Reliable dealers will tell you just what their garments are made of, but the unscrupulous pass off the imitations as the genuine article.
The business of dyeing furs was developed first in Germany, when that country led the world in making dyes. Now that New York is competing with London as a great fur market many of the best German dyers are at work there. From the standpoint of the consumer, the chief objection to dyed fur is that the natural never
fades, while the dyed one is almost certain to change its hue after a time.
Now let us go into the rooms where the furs are made up. It is like a tailor shop. Here is a designer, evolving new patterns out of big sheets of paper. There are the cutters, making trimmings, stoles, neck pieces, and coats. Each must be a colour expert, for a large part of the secret of fashioning a beautiful fur garment is in the skillful matching of the varying shades to give pleasing effects. Were the skins for a coat sewn together just as they come from the bale, the garment resulting would be a weird-looking patchwork. Even before the skins are selected, they must be graded for the colours and shadings which go far to determine their value. There are no rules for this work; it takes a natural aptitude and long experience. In the London warehouse of the Hudson’s Bay Company, the men of a single family have superintended the grading of all the millions of skins handled there for more than one hundred years.
Turn over this unfinished beaver coat lying on the bench and look at the wrong side. See how small are the pieces of which it is made and how irregular are their shapes. It is a mass of little patches, yet the outer, or right side, looks as though it were made of large skins, all of about the same size and shape. A coat of muskrat, transformed by dyeing into Hudson seal, may require seventy-five skins; a moleskin coat may contain six hundred. But in making up either garment each skin must be cut into a number of pieces and fitted to others in order to get the blending of light and dark shades which means beauty and quality.
The Eskimo woman and her children wear as every-day necessities furs which if made into more fashionable garments would bring large sums. Usually the whole family goes on the annual trip to the trading post.
As Saskatchewan was not made a province until 1904, Regina is one of the youngest capital cities in Canada. It was for many years the headquarters of the Mounted Police for all the Northwest.
CHAPTER XXIII
SASKATCHEWAN
We have left Winnipeg and are now travelling across the great Canadian prairie, which stretches westward to the Rockies for a distance of eight hundred miles. This land, much of which in summer is in vast fields of golden grain, is now bare and brown, extending on and on in rolling treeless plains as far as our eyes can reach. Most of it is cut up into sections a mile square, divided by highway spaces one hundred feet wide. However, an automobile or wagon can go almost anywhere on the prairie, and everyone makes his own road.
Sixty miles west of Winnipeg we pass Portage la Prairie, near where John Sanderson, the man who filed the first homestead on the prairies, is still living. This part of the Dominion was then inhabited by Indians, and its only roads were the buffalo trails made by the great herds that roamed the country. To-day it is dotted with the comfortable homes of prosperous farmers, and the transcontinental railways have brought it within a few days’ travel of the Atlantic and the Pacific seaboards.
A hundred and fifty miles farther west we cross the boundary into Saskatchewan, the greatest wheat province of the Dominion. It has an area larger than that of any European country except Russia, and is as large as France, Belgium, and Holland combined. From the United States boundary, rolling grain lands extend northward through more than one third of its area. The remainder is mostly forest, thinning out toward Reindeer Lake and Lake Athabaska at the north, and inhabited chiefly by deer, elk, moose, and black bear. There are saw-mills at work throughout the central part of the province, and the annual lumber cut is worth in the neighbourhood of two million dollars.
Except at the southwest, Saskatchewan is well watered. The Saskatchewan River, which has many branches, drains the southern and central sections. This stream in the early days was a canoe route to the Rockies. For a long time afterward, when the only railway was the Canadian Pacific line in the southern part of the province, the river was the highway of commerce for the north. It was used largely by settlers who floated their belongings down it to the homesteads they had taken up on its banks. Now the steamboats that plied there have almost entirely disappeared. The northern part of the province is made up of lakes and rivers so numerous that some of them have not yet been named. The southwest is a strip of semi-arid land that has been brought under cultivation by irrigation and now raises large crops of alfalfa.
A small part of southwestern Saskatchewan, near the Alberta boundary, is adapted for cattle and sheep raising. The Chinook winds from the Pacific keep the winters mild and the snowfall light, so that live stock may graze in the open all the year round. Elsewhere the winters are extremely cold. The ground is frozen dry and hard, the lakes and streams are covered with ice, and the average elevation of about fifteen hundred feet above sea level makes the air dry and crisp. The people do not seem to mind the cold. I have seen children playing out-of-doors when it was twentyfive degrees below zero. The summers are hot, and the long days of sunshine are just right for wheat growing.
After travelling fourteen or fifteen hours from Winnipeg, we are in Regina, the capital of Saskatchewan, on the main line of the Canadian Pacific, about midway between Winnipeg and the Rockies. I visited it first in 1905, when the province was less than a year old. Until that time all the land between Manitoba and British Columbia, from the United States to the Arctic Ocean, belonged to the Northwest Territories. It had minor subdivisions, but the country as a whole was governed by territorial officials with headquarters at Regina. As the flood of immigrants began to spread over the West, the people of the wheat belt decided that they wanted more than a territorial government and so brought the matter before the Canadian parliament. As a result the great inland provinces of Saskatchewan
and Alberta were formed. They are the only provinces in the Dominion that do not border on the sea.
Regina was then a town of ragged houses, ungainly buildings, and wide streets with board sidewalks reaching far out into the country. One of the streets was two miles long, extending across the prairie to the mounted police barracks and the government house. Regina was the headquarters of the Northwest Mounted Police until that organization was amalgamated with the dominion force as the Royal Canadian Mounted Police, and the city is still a training camp for recruits. Saskatchewan was not then old enough to have a state house, and the government offices were in rooms on the second floors of various buildings. Most of the provincial business was done in a little brick structure above the Bank of Commerce.
The hotels of the town were then packed to overflowing, even in winter, and in the spring and summer it was not uncommon to find the halls filled with cots. I had to sleep in a room with two beds, and with a companion who snored so that he shook the door open night after night. It was of no use to complain, as the landlord could tell one to go elsewhere, knowing very well that there was no elsewhere but outdoors.
To-day Regina is ten times as large as it was twenty years ago. It is a modern city with up-to-date hotels, ten banks, handsome parliament buildings, and twelve railway lines radiating in every direction. It is the largest manufacturing centre between Winnipeg and Calgary, and an important distributing point for farm implements and supplies.
The dome of the capitol building, which was completed in 1911, can now be seen from miles away on the prairie. This is an imposing structure five hundred and forty-two feet long, situated in the midst of a beautiful park on the banks of an artificial lake made by draining Wascana Creek. The city has many other parks, and the residence streets are lined with young trees, planted within the last twenty years. Forty miles to the east is a government farm at Indian Head, where experiments are made in growing and testing trees suited to the prairies. Fifty million seedlings have been distributed in one year
among the farms and towns. Out in the country the trees are planted as windbreaks and to provide the farmers with fuel. They have greatly changed the aspect of the prairies within the last two decades.
The grain lands of western Canada begin in Manitoba in the fertile Red River valley, which is world famous for the fine quality of its wheat. From here to the Rockies is a prairie sea, with farmsteads for islands.
American windmills tower over Saskatchewan prairie lands that were largely settled by American farmers. The province is still so thinly populated that it has only five people to every ten square miles.
The wheat harvest, like time and tide, waits for no man and when the crop is ready it must be promptly cut. The grain is usually threshed in the fields and sent at once to the nearest elevator.
While in Regina I have had a talk with the governor-general of Saskatchewan in his big two-story mansion that twenty years ago seemed to be situated in the middle of the prairie. When I motored out to visit His Excellency, although I was wrapped in buffalo robes and wore a coon-skin coat and coon-skin cap, I was almost frozen, and when I entered the mansion it was like jumping from winter into the lap of summer. At one end of the house is a conservatory, where the flowers bloom all the time, although Jack Frost has bitten off all other vegetation with the “forty-degrees-below-zero teeth” he uses in this latitude.
From Regina, the main line of the Canadian Pacific Railway runs west to Calgary. Were we to travel by that route, we should pass through Moose Jaw and Swift Current, two important commercial centres for the wheat lands. The story is told that Lord Dunsmore, a pioneer settler, once mended the wheel of his prairie cart with the jaw bone of a moose on the site of the former city, and thus gave the place its name. Moose Jaw is a live stock as well as a wheat
shipping point. It has the largest stock yards west of Winnipeg. An extensive dairying industry has grown up in that region.
North of Regina are Prince Albert and Battleford, noted for their fur trade and lumber mills, and also Saskatoon, the second largest city of the province, which we shall visit on our way to Edmonton. At Saskatoon is the University of Saskatchewan, which was patterned largely after the University of Chicago. It has the right to a Rhodes scholarship; and its departments include all the arts and sciences.
As sixty per cent. of the people are dependent upon agriculture, farm courses receive much attention. A thousand-acre experimental farm is owned by the university and the engineering courses include the designing and operation of farm machinery. Even the elementary schools are interested in agriculture, a campaign having been carried on recently to eradicate gophers, which destroy the wheat. The children killed two million of these little animals in one year, thereby saving, it is estimated, a million bushels of grain. A department of ceramics has been organized at the university to experiment with the extensive clay deposits of the province, the various grades of which are suited for building brick, tile, pottery, and china. Saskatchewan’s only other mineral of any importance is lignite coal, although natural gas has been discovered at Swift Current.
CHAPTER XXIV
THE WORLD’S LARGEST WHEATFIELD
For the past two weeks I have been travelling through lands that produce ninety per cent. of Canada’s most valuable asset—wheat. The Dominion is the second greatest wheat country in the world, ranking next to the United States. It is the granary of the British Empire, raising annually twice as much wheat as Australia and fifty million bushels more than India. The wheat crop is increasing and Canada may some day lead the world in its production. These prairies contain what is probably the most extensive unbroken area of grain land on earth. In fact, so much wheat is planted in some regions that it forms an almost continuous field reaching for hundreds of miles. The soil is a rich black loam that produces easily twenty bushels to an acre, and often forty and fifty.
The Canadian wheat belt extends from the Red River valley of Manitoba to the foothills of the Rockies, and from Minnesota and North Dakota northward for a distance greater than from Philadelphia to Pittsburgh. New wheat lands are constantly being opened, and large crops are now grown in the Peace River country, three hundred miles north of Edmonton.
A man who is an authority on wheat raising tells me that the possible acreage in the Canadian West is enormous. Says he:
“We have something like three hundred and twenty thousand square miles of wheat lands. Divide this in two, setting half aside for poor soil and mixed farming, and there is left more than one hundred-thousand square miles. In round numbers, it is one hundred million acres, and the probability is that it can raise an average of twenty-five bushels to the acre. This gives us a possible crop of
