P1: SFK/UKS BLBS102-c28 P2: SFK BLBS102-Simpson March 21, 2012 13:54 568 Trim: 276mm X 219mm Printer Name: Yet to Come Part 5: Fruits, Vegetables, and Cereals Table 28.6 Nutrients in Fruit and Processed Products (454 g) Apples Raw fresh Applesaucea Unsweetened juice Apple juice Frozen sliceda Apple buttera Dried, 24% Dehydrated, 2% Sodium (mg) Potassium (mg) Vitamin A (IU) Thiamin (mg) Riboflavin (mg) Niacin (mg) Vitamin C (mg) 9 64 23 32 459 295 354 458 308 1143 22,581 3311 380 180 180 – 80 – – 0.12 0.08 0.08 0.03 0.05 0.05 0.26 0.02 0.08 0.05 0.05 0.07 0.014 0.09 0.053 0.026 0.3 0.2 0.2 0.4 1.0 0.7 2.3 2.9 16 5 33 48 47 Source: Composition of foods Agriculture Handbook No a With sugar Anthocyanins REFERENCES Anthocyanins often occur as a complex mixture Grape extracts can have glucosides, acetyl glucosides, and coumaryl glucosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin The color of anthocyanins is pH dependent An anthocyanin is usually red at a pH of 3.5, becoming colorless and then shifting to blue as the pH increases Fruit anthocyanin content increases with maturity In stone fruits (peaches and plums) and pome fruits (apple and pears), anthocyanins are restricted to the skin, whereas in soft fruits (berries), they are present both in skin and flesh Anthocyanins are used as coloring agents for beverages and other food products Anonymous 1980 Cider In: National Association of Cider Makers NACM, Dorchester, Dorset Bissessur J et al 2001 Reduction of patulin during apple juice clarification J Food Protection 64: 1216–1222 deMan JM 1999 Principles of food chemistry, 3rd edn Aspen Publishers, Gaithersburg, MD, pp 120–137 Ellis GP 1959 The Maillard reaction In: ML Wolfram, RS Tipson (eds.) Advances in Carbohydrates Chemistry, Volume 14 Academic Press, New York Flath RA et al 1967 J Agric Food Chem 15: 29–38 Canadian apple industry http://www.ats.agr.gc.ca/can/4480-eng htm Accessed on December 06, 2011 FAO 2003 http://www.statcan.gc.ca/pub/82-003-x/2008004/ article/6500821-eng.pdf Accessed on December 06, 2011 Statistics Canada 2003 http://www.statcan.ca/english/ads/23F0001 XCB/highlight.htm Accessed on December 07, 2011 Nelson PE, Tresler DK 1980 Fruit and Vegetable Juice Production Technology, 3rd edn AVI Co., Westport, CT Peterson J, Dwyer J 1998 Flavonoids: dietary occurrence and biochemical activity Nutrition Research 18: 1995–2018 Somogyi LP et al 1996a Processing Fruits: Science and Technology, Volume 2, Major Processed Products Technomic Publishing Co., Lancaster, PA, pp 9–35 Somogyi LP et al 1996b Processing Fruits: Science and Technology, Volume 1, Biology, Principles and Applications Technomic Publishing Co., Lancaster, PA, pp 1–24 Smock RM, Neubert AM 1950 Apples and Apple Products Interscience Publishers, New York Swanson KMJ 1989 Microbiology and preservation In: DL Downing (ed.) Processed Apple Products Van Nostrand Reinhold/AVI, New York, pp 343–363 Van Gorsel H et al 1992 Compositional characterisation of prune juice J Agric Food Chem 40: 784–789 Flavans Flavans are what was once called catechins, leucoanthocyanins, proanthocyanins, and tannins They occur as monoflavans, biflavans, and triflavans Monoflavans are found in ripe fruits and fresh leaves Biflavans and triflavans are found in fruits such as apples, blackberries, blackcurrants, cranberries, grapes, peaches, and strawberries (Table 28.6) FURTHER READING Arthey D, Ashwurst PR 2001 Fruit Processing: Nutrition, Products and Quality Management Aspen Publishers, Gaithersburg, MD, p 312 Enachescu DM 1995 Fruit and Vegetable Processing FAO Agricultural Services Bulletin 119, FAO, p 382 Jongen WMF 2002 Fruit and Vegetable Processing: Improving Quality (Electronic Resource) CRC Press, Boca Raton, FL Salunkhe DK, Kadam SS 1998 Handbook of Vegetable Science and Technology: Production, Composition, storage and Processing Marcel Dekker, New York, p 721 P1: SFK/UKS BLBS102-c29 P2: SFK BLBS102-Simpson March 21, 2012 13:27 Trim: 276mm X 219mm Printer Name: Yet to Come 29 Biochemistry of Vegetable Processing Moustapha Oke, Jissy K Jacob, and Gopinadhan Paliyath Introduction Classification of Vegetables Chemical Composition of Vegetables Vitamins Minerals Dietary Fiber Proteins Lipids Volatiles Water Organic Acids Pigments Phenolic Components Carbohydrates Turgor and Texture Vegetable Processing Harvesting and Processing of Vegetables Preprocessing Operations Harvesting Sorting and Grading Washing Peeling Cutting and Trimming Blanching Canning Procedure Canned Tomatoes Peeling Inspection Cutting Filling Exhausting Processing Time of Canned Tomatoes Tomato Juice Processing Processing Comminution Extraction Deaeration Homogenization Salting Quality Attributes of Tomato and Processed Products Physicochemical Stability of Juices Kinetic Stability Physical Stability Enhancing Nutraceutical Quality of Juice Products Minimally Processed Vegetables Definitions Processing Quality of MPR Further Reading References Abstract: Vegetables are very important components of diet Vegetables are highly perishable, and transportation, storage, and distribution require low-temperature conditions Vegetables are processed into juice, sauce, and canned under aseptic conditions This enables long-term storage of processed products Tomato is the major produce that is processed into juice and sauce Preservation of nutritional components is compromised during processing Stability of juice is influenced by the particle size distribution INTRODUCTION Vegetables and fruits have many similarities with respect to their composition, harvesting, storage properties, and processing In the true botanical sense, many vegetables are considered as fruits Thus, tomatoes, cucumbers, eggplant, peppers, and so on could be considered as fruits, since they develop from ovaries or flower parts and are functionally designed to help the development and maturation of seeds However, the important distinction between fruits and vegetables is based on their use In general, most vegetables are immature or partially mature and are consumed with the main course of a meal, whereas fruits are generally eaten alone or as a dessert The United States is one of the world’s leading producers and consumers of Food Biochemistry and Food Processing, Second Edition Edited by Benjamin K Simpson, Leo M.L Nollet, Fidel Toldr´a, Soottawat Benjakul, Gopinadhan Paliyath and Y.H Hui C 2012 John Wiley & Sons, Inc Published 2012 by John Wiley & Sons, Inc 569 P2: SFK BLBS102-Simpson March 21, 2012 13:27 Trim: 276mm X 219mm 570 Printer Name: Yet to Come Part 5: Fruits, Vegetables, and Cereals World vegetable supply (tonnes) World vegetable supply 250,000,000 Beans 200,000,000 Maize Onions 150,000,000 Peas Pepper 100,000,000 Potatoes Roots and tuber dry equiv 50,000,000 Roots, other Sweet potatoes 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Tomatoes Yams Year World vegetable supply World vegetable supply (tonnes) 350,000,000 300,000,000 China 250,000,000 India 200,000,000 Japan 150,000,000 Korea, Republic of Myanmar 100,000,000 Nigeria 50,000,000 Philippines Russian federation 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 P1: SFK/UKS BLBS102-c29 Vietnam Year Figure 29.1 An estimate of world vegetable production by region, and type of vegetable (Source: FAOSTAT 2010.) vegetables and fruits In 2002, the farm gate value of vegetables and melons (including mushrooms) sold in the United States reached $17.7 billion Annual per capita use of fresh vegetables and melons rose 7% between 1990–1992 and 2000–2002, reaching 442 pounds, as fresh consumption increased and consumption of processed products decreased According to Food and Agriculture Organization (FAO) data, the world production of vegetables has increased from 147 million metric tons (Mt) in 1992 to 350 million Mt in 2005 (Fig 29.1) Potato, tomato, sweet potato, onions and so on are the major vegetables that are produced across the world (Fig 29.1) Vegetables remain a popular choice for consumers worldwide In general, the supply of vegetables per capita has increased in developing countries, but lags behind in certain parts of the world (Table 29.1) In 2002, each individual ate an average of 110 Table 29.1 Changes in Vegetable Supply in Different Parts of the World Region 1979 2000 World Developed countries Developing countries Africa North and Central America South America Asia Europe Oceania 66.1 107.4 51.1 45.4 88.7 43.2 56.6 110.9 71.8 101.9 112.8 98.8 52.1 98.3 47.8 116.2 112.5 98.7 Source: Fresco LO, Baudoin WO 2002 P1: SFK/UKS BLBS102-c29 P2: SFK BLBS102-Simpson March 21, 2012 13:27 Trim: 276mm X 219mm Printer Name: Yet to Come 571 29 Biochemistry of Vegetable Processing Table 29.2 World Production of Selected Vegetables in 2002 in Metric Tons (Mt) Production in 2002 Countries World Africa Asia Australia Canada European Union (15) New Zealand North and Central America South America United States of America Fresh Vegetable 233,223,758 12,387,390 199,192,449 80,000 124,000 8,462,000 120,000 2,023,558 3,503,611 1,060,000 Tomatoes 108,499,056 12,428,174 53,290,273 400,000 690,000 14,534,582 87,000 15,837,877 6,481,410 12,266,810 kilograms of vegetables (including potatoes), up from 106 kg a decade earlier Potatoes represented 35% of all vegetables consumed In 2008, greater than 50% of women and nearly 40% of men reported to have more than servings of fruits and vegetables per day (http://www.statcan.gc.ca/pub/82-229-x/ 2009001/deter/fvc-eng.htm.) The world production of certain vegetables is shown in Tables 29.2 and 29.3 From 2002 to 2005, the increase in vegetable production observed was primarily due to an increase in production of potatoes (Fig 29.1) In the United States, consumption of fresh vegetables (excluding potatoes) has increased from 60 kg in 1986 to 72 kg in 2003 In 2003, the most consumed fresh vegetable was head lettuce at 12 kg, followed by onions at kg and fresh tomatoes at kg In the same year, the consumption of processed tomatoes per capita was 35 kg and processed sweet corn 9.5 kg In Canada, the consumption of fresh vegetables (excluding potatoes) has been increasing steadily reaching 70.2 kg/capita in 1997 from 41 kg/capita in 1971 Also in 1997, the consumption of fresh vegetables has declined 2.4% from the amount of fresh vegetables consumed in 1996 (71.9 kg/ capita) Lettuce (16%) is the most consumed fresh vegetable followed by onions (12.1%), carrots (12.0%), tomatoes (11.6%), and cabbage (8.1%) Brussels sprouts, parsnips, asparagus, beets, and peas each represent less than 1.0% of Canadian fresh vegetable diet On a per capita basis, Canada has one of the highest consumption rates of fresh vegetables in the world Frozen vegetable consumption has de- Table 29.3 Production of Tomato in North America Tomato Production (Mt) Year 2002 World Canada United States of America Mexico 108,499,056 690,000 12,266,810 2,083,558 Source: Food and Agricultural Organization (FAO) Table 29.4 Classification of Vegetables Types of Vegetables Earth vegetables Roots Modified stems Corms Tubers Modified buds Bulbs Herbage vegetables Leaves Petioles (leaf stalk) Flower buds Sprouts, shoots (young stems) Fruit vegetables Legumes Cereal Vine fruits Berry fruits Tree fruits Examples Sweet potatoes, carrots Taro Potatoes Onions, garlic Cabbage, spinach, lettuce Celery, rhubarb Cauliflower, artichokes Asparagus, bamboo shoots Peas, green beans Sweet corn Squash, cucumber Tomato, eggplant Avocado, breadfruit clined 3.4% to 5.6 kg/capita while canned vegetables and vegetable juices have increased 2.4% to 12.9 kg/capita for the same period Vegetable purchases by consumers represent 6.6% of total food expenditures, virtually unchanged in the past 10 years CLASSIFICATION OF VEGETABLES Vegetables can be classified according to the part of the plant from which they are derived, such as leaves, roots, stems, and buds as shown in Table 29.4 They also can be classified into “wet” or “dry” crops Wet crops such as celery or lettuce have water as their major component, whereas dry crops such as soybeans have carbohydrates, protein, and fat as their major constituents, and relatively low amount of water Soybeans, for example, are composed of 36% protein, 35% carbohydrate, 19% fat, and 10% water Wet crops tend to perish more rapidly compared to dry crops CHEMICAL COMPOSITION OF VEGETABLES Fresh vegetables contain more than 70% water, and very frequently greater than 85% Beans and other dry crops are exceptions The protein content is often less than 3.5% and the fat content less than 0.5% Vegetables are also important sources of digestible and indigestible carbohydrate, as well as of minerals and vitamins They contain the precursor of vitamin A, betacarotene, and other carotenoids Carrots are one of the richest sources of beta-carotene (provitamin A) P1: SFK/UKS BLBS102-c29 P2: SFK BLBS102-Simpson March 21, 2012 572 13:27 Trim: 276mm X 219mm Printer Name: Yet to Come Part 5: Fruits, Vegetables, and Cereals Vitamins Vegetables are major contributors to our daily vitamin requirements The nutrient contribution from a specific vegetable is dependent on the amount of vitamins present in the vegetable, as well as the amount consumed The approximate percentage that vegetables contribute to daily vitamin intake is: vitamin A-50%, thiamine-60%, riboflavin-30%, niacin-50%, and vitamin C-100% Vitamins are sensitive to different processing conditions including; exposure to heat, oxygen, light, free water, and traces of certain minerals Trimming, washing, blanching, and canning can cause loss in vitamin content of fruits and vegetables Minerals The amount and types of minerals depend on the specific vegetable Not all minerals in plant materials are readily available and are mostly in the form of complexes An example is calcium found in vegetables as calcium oxalate Green leafy vegetables are rich in magnesium and iron Dietary Fiber The major polysaccharides found in vegetables include starch, and dietary fiber such as cellulose, hemicellulose, pectic substances, and lignin Cell walls in young vegetables are composed of cellulose As the produce ages, cell walls become higher in hemicellulose and lignin These materials are tough and fibrous and their consistency is not affected by processing Some vegetables such as potato also contain varying amounts of starch resistant to hydrolysis (resistant starch) Resistant starch is not digested as efficiently as regular starch, and reaches the colon where they undergo microbial fermentation The short chain fatty acids liberated during the digestion of resistant starch is considered to be beneficial to the health Roots of vegetables such as endive are rich in fructooligosaccharides such as inulin, which are considered to possess health regulatory function Proteins Most vegetables contain less than 3.5% protein Soybeans are an exception In general, plant proteins are major sources of dietary protein in places where animal protein is in short supply Plant proteins, however, are often deficient or limiting in one or more essential amino acids Wheat protein is limiting in lysine, while soybean protein is limiting in methionine Leafy green vegetables are also rich in proteins, especially photosynthetic proteins such as ribulose-bis-phosphate carboxylase oxygenase (RubisCO) and other chloroplast proteins Multiple sources of plant proteins are recommended in the diet because of the absence of key amino acids in some cases, as a part of the internal cell structure (oleosomes) Even though lipids are a minor component of vegetables, they play an important role in the characteristic aroma and flavor of the vegetable The characteristic aroma of cut tomato and cucumber results from components released from the lipoxygenase pathway, through the action of lipoxygenase upon linoleic and linolenic acids and the hydroperoxide lyase action on the peroxidized fatty acids to produce volatile compounds This action is accentuated, when the tissue is damaged The results of the action of lipoxygenase are sometimes deleterious to the quality—for example, the action of lipoxygenase on soybean oil leads to rancid flavors and aromas Volatiles The specific aroma of vegetables is due to the amount and diversity of volatiles they contain Volatiles are present in extremely small quantities (