Từ điển công nghệ thực phẩm - V

V Vaccenic acid One of the trans-18:1 fatty acids present at significant levels in milk fats as well as in other foods. Vacuum A space entirely devoid of matter or from which the air has been completely removed. In practi- cal terms, a vacuum is an enclosed region of space in which the pressure has been reduced (below normal atmospheric pressure) so that processes occurring within the region are unaffected by the residual matter. Vacuum cooling Technique based on liquid evapo- ration which produces a rapid cooling effect in products containing free water. Suitable only where removal of the free water will not cause structural damage and where there is no barrier, e.g. a thick wax cuticle, to water loss. Subjecting suitable products to vacuum pressure allows part of the water contained in them to boil out at relatively low temperatures. Used successfully in reducing postharvest deterioration in fruits and vegetables, thus prolonging shelf life, during processing of some products, including liquid foods and bakery products, and rapid cooling of cooked meat, fish products and ready meals. Vacuum drying Removal of liquid from a solid mate- rial while in a vacuum system, to lower the tempera- ture at which evaporation takes place and thus pre- vent heat damage to the material. Vacuum evaporation Concentration technique in which the use of high temperatures is avoided by sub- jecting the substance to a vacuum, causing it to boil at a lower temperature. The process is performed in a chamber surrounded by a water jacket through which water is circulated to control temperature. Particularly useful for products where heat-induced protein dena- turation should be avoided, e.g. liquid egg whites and skim milk. Vacuum impregnation The direct introduction of ingredients into foods in a controlled manner, by way of their pores. A vacuum is applied to a solid-liquid system so that the gas within the pores of the solid ex- pands and flows out. Atmospheric pressure is then re- stored to compress residual gas and draw the liquid into the pores. Vacuum impregnation can be used to improve the rate of mass transfer in processes such as osmotic drying, salting and acidification. Vacuum packaging Packaging process in which some or all of the air is removed from flexible or rigid containers before sealing. This form of packaging is used to preserve flavour, inhibit bacterial growth and prolong the shelf life of food. Vacuum pans Sealed devices that control the crys- tallization of solids from liquids by lowering the pressure within the sealed container. Vacuum pans are widely used for crystallization during the manufacture of sugar. Valeraldehyde Synonym for pentanal. Organic compound present in many foods that has an unpleas- ant odour and a low odour threshold value. One of the main compounds that can cause off odour in sake. Valeric acid Synonym for pentanoic acid. Volatile fatty acid comprising 5 carbon atoms and a single car- boxylic acid group. Contributes to the aroma of ma- ture cheese. Uses include as a reactant in production of aroma compounds and flavourings. Also one of the main malodorous pollutants from livestock houses. Valine Essential amino acid important for growth. Good sources include soy meal, brown rice, cot- tage cheese, fish, meat, nuts and legumes. Valtellina Casera cheese Italian semi hard cheese made on an artisanal or semi industrial scale from semi skimmed cow milk. Granted controlled Denomination of Origin status. Rind has a characteristic straw-yellow colour which intensifies with ripening. Flavour is sweet with a note of dried fruits. Eaten on its own or as an ingredient of a range of local cooked dishes and salads. Valves Mechanical devices, either manual or auto- matic, for controlling the passage of fluids through pipes or ducts. Vanadium Element with the chemical symbol V that is intermediate between the metals and non-metals. Vanaspati Grainy hydrogenated vegetable oils used as an alternative to ghee in India and Pakistan. Simi- lar to margarines and often fortified with vitamin A and vitamin D. Vancomycin One of the glycopeptide antibiotics produced by Streptomyces orientalis. Used to treat serious life-threatening human infections caused by 441 Vanilla Vegetable burgers Gram positive bacteria. Acts by inhibiting proper cell wall synthesis. Guidelines for its use have been produced as a consequence of the increasing emer- gence of vancomycin-resistant enterococci. Vanilla Natural flavourings produced by curing of fully grown but unripe beans (pods) of Vanilla planifo- lia or V. tahitensis. Curing causes hydrolysis of gluco- vanilla to produce glucose and the flavour compound, vanillin. Glucose is then involved in nonenzymic browning via the Maillard reaction with bean pro- teins. Major vanilla producing countries are Mexico, Madagascar, Indonesia and Tahiti, each country pro- ducing vanilla with a distinctive flavour profile. Al- though vanillin is the main flavour component of va- nilla it comprises only about 3% of the total flavour compounds and aroma compounds. Thus com- position of minor flavour and aroma compounds is an important determinant of flavour. Vanilla beans Seed pods of the orchids Vanilla plani- folia, V. tahitensis or V. pompona. Harvested while green, then cured for 3 to 6 months before being used in the production of vanilla. Major vanilla producing countries include Madagascar, Mexico, Indonesia and Tahiti. Vanillic acid Phenolic compound produced as an in- termediate in bioconversions of ferulic acid to vanillin. Also found as a pollutant in olive oil mills effluents. Vanillin Substituted phenol that is the main flavour compound of vanilla. Synthetic vanillin is also manu- factured for use in flavourings. Used as a cheaper alternative to vanilla in a wide range of foods, such as ice cream, bakery products, sugar confection- ery and beverages. Vapona Alternative term for the insecticide dichlor- vos. Vaporization Process by which moisture or another substance is diffused or suspended in the air, becoming converted into vapour. Examples include the rapid change of water into steam, especially in boilers. Vapours Gaseous state of a substance, e.g. water vapour , at a temperature lower than its critical point, that can be made into a liquid by the application of pressure . Vapours are produced from liquids by evaporation and from solids by sublimation. var Abbreviation generally applied to variety. Variety Taxonomic rank below subspecies, usually abbreviated to var. Varieties are usually the result of selective breeding and diverge from the parent in rela- tively minor ways. Varieties may be distinguished within a given subspecies by, for example, metabolic and/or physiological properties (biovar. or biotype), morphology (morphovar. or morphotype), patho- genicity for specific hosts (pathovar. (pv.) or patho- type), susceptibility to lysis by specific bacterio- phages (phagovar. or phagotype) or serological char- acteristics (serovar. or serotype). However, these terms are often used loosely, in a non-taxonomic sense. Varnishes Resins dissolved in liquids which are used to coat wood or metals. Form a transparent, shiny, hard surface when dry. Varnishes based on epoxy resins are often used for coating the interior of food cans. Vats Large tubs or tanks used to hold or store liquids. Examples include fermentation vats used in wine- making and vats used during cheesemaking. Veal Meat from young calves, usually cattle which are slaughtered at <20 weeks of age. Commonly, veal is produced under semi-intensive systems in which calves are fed on milk-based concentrated feeds to produce very light-coloured (white or pink) meats. Veal calves are prevented from feeding on fibrous feeds in order to prevent development of darker col- oured, stronger flavoured meat. Typically, veal is very lean and tender, and has a delicate flavour. The high- est quality veal tends to be produced from calves slaughtered at 12-16 weeks of age at body weight of 70-90 kg; these calves are often of French lineage, be- ing from breeds such as the Belgian blue or Charolais. Veal is expensive to produce and, sometimes, calves are treated with growth promoters (e.g. anabolic ster- oids) to increase the weight of veal carcasses. Vectors Autonomously replicating DNA molecules (e.g. plasmids, cosmids, viruses and yeast artificial chromosomes) into which foreign DNA fragments can be inserted. They can then be transformed into suitable host cells and propagated. In addition to ori- gins of replication, vectors usually contain selectable markers that allow selection of recombinant cells. They may also contain sequences that direct expression of cloned genes in host cells. Vegan diet Strict vegetarian diet which contains no animal foods of any kind. Vegan foods Vegetarian foods suitable for a ve- gan diet, i.e. excluding meat, eggs, milk, butter, cheese and all other animal foods. Vegetable burgers Patties made from mashed or chopped vegetables, sometimes also containing ce- real or nut ingredients, eaten as an alternative to meat- based burgers such as beefburgers. Commonly used ingredients include beans, mushrooms, on- ions and carrots. Spices and condiments are added to produce the desired flavour. Health benefits compared with meat-based burgers include low fat and sodium contents, little or no cholesterol content and increased dietary fibre levels. Also known as veggie burgers. 442 Vegetable fats Vending machines Vegetable fats Lipid-rich vegetable products that are solid at room temperature. May be produced by hy- drogenation of vegetable oils. Used in cooking and as food ingredients. Include cocoa butter, sal fats, shea nut butter and vanaspati. Vegetable juice beverages Beverages prepared from vegetable juices with addition of other ingre- dients. Vegetable juices Juices extracted from vegetables. Drunk as beverages in a similar way to fruit juices. Include carrot juices and cabbage juices. Vegetable nectars Vegetable juice beverages made by addition of water and/or sugar, and option- ally other ingredients, to vegetable juices. Vegetable oils Lipid-rich vegetable products that are liquid at room temperature. Extracted from plant mate- rial including seeds, fruits or nuts. Often contain phytosterols. Used widely as cooking oils and salad oils and as flavourings. Include cottonseed oils, olive oils, sunflower oils, soybean oils and essential oils. Vegetable pickles Vegetables preserved in liquids such as brines or vinegar and eaten as an accompa- niment to a meal. Examples include pickled onions and cucumber pickles. Vegetable preserves Vegetables that have been preserved by immersing in brines, vinegar or oils. Vegetable products Foods derived from vegeta- bles , or containing vegetables as the main ingredients. Includes a wide range of foods, such as soups, sal- ads, vegetable oils and pickles. Vegetable proteins Proteins sourced from vegeta- ble tissue. Preferred by some consumers due to health benefits. Quality of vegetable proteins, especially with respect to amino acids composition, varies according to source, but many plant breeding programmes have aimed to improve protein quality of individual crops. Legumes, particularly soybeans, are especially rich in protein. Textured vegetable proteins, usually derived from soybeans, are used as meat substitutes and meat extenders. Vegetable pulps Preparations made from vegeta- bles by mashing the cooked flesh. Used as ingredients in various dishes, such as soups, sauces and cas- seroles. Vegetable purees Vegetables that have been mashed, usually after cooking, to a smooth, thick con- sistency by various means, such as forcing through sieves or blending in food processors. Used as gar- nishes, side dishes or ingredients in dishes such as sauces and soups, or beverages. Vegetable rennets Enzymes sourced from plant materials that are used as substitutes for animal ren- nets in coagulation of milk for cheesemaking. Include enzymes extracted from flowers of cardoons or curdle thistle (Cynara cardunculus). Vegetables Plants cultivated for an edible part, e.g. root, tuber, leaf or flower buds (as in broccoli and cauliflowers), or the edible parts of such plants. Vegetable salads Dishes prepared from a mixture of vegetables, raw or cooked, sometimes served in sauces or dressings. Vegetable soups Soups containing vegetables as the main ingredients, e.g. gazpacho or minestrone. Marketed in cans or retort pouches, and also as frozen or instant soups. Vegetarian diet Diet based on plant foods, and which excludes meat and fish, and, in some cases, other animal foods. Lacto-ovo vegetarians consume dairy products and eggs, while those following a vegan diet consume no animal products at all. Vege- tarianism is adopted for a variety of reasons, including ethical and religious beliefs as well as for nutri- tional/health benefits. The positive health effects re- ported for the diet have been attributed to relatively low contents of fats and cholesterol and the high contents of some vitamins and minerals. Inclusion of supplements in the diet may be necessary to prevent the risk of deficiency in vitamin B 12 and some miner- als, such as iron, zinc and iodine. Vegetarian foods Meat-free foods suitable for inclu- sion in a vegetarian diet. Include pasta, soy products, vegetable burgers and simulated meat substitutes. Much of the recent growth in the vege- tarian food market has been fuelled by non-vegetarians who are keen to cut down on meat consumption and who perceive vegetarian foods as a healthy option. Veillonella Genus of anaerobic, coccoid Gram nega- tive bacteria of the Veillonellaceae family that pos- sess lactate fermenting abilities. Occur as parasites in the mouth, and gastrointestinal and respiratory tracts of humans and animals. Species may be included in competitive exclusion cultures, which are fed to ani- mals (e.g. poultry) to prevent intestinal colonization by pathogens (e.g. Salmonella spp.). Velvet beans Seeds produced by Mucuna pruriens rich in proteins and fibre but containing antinutri- tional factors that must be destroyed by cooking prior to consumption. Vendace Freshwater fish species (Coregonus al- bula) from the family Salmonidae; distributed across northwest Europe. Normally marketed fresh; in Swe- den, roes are used as caviar substitutes. Vending machines Machines that dispense articles such as packaged foods or beverages, usually when a coin or token is inserted. 443 Venison Vinegar Venison Meat from deer. It is very lean and has a strong gamey flavour and aroma, which may be de- creased by marination before cooking. The prime cuts are from the loin areas of deer carcasses. Pre- slaughter stress, particularly the holding of farmed or harvested wild deer in unfamiliar surroundings before slaughter, is associated with high ultimate pH values in deer carcasses and venison with a dark cutting appear- ance. In broader use, the term is used to describe meat from antelopes, caribou, elks, moose and reindeer. Also known as deer meat. Veratryl alcohol Aryl alcohol (3,4-dimethoxybenzyl alcohol) synthesized by white rot fungi and involved in activation of their ligninolytic enzyme systems. En- zymes act on plant material and can be used for vari- ous functions, including removal of phenols from fruit juices, treatment of olive oil mills effluents and detoxification of lignocellulosic hydrolysates. Verbascose Oligosaccharide composed of fructose, galactose and glucose residues. Vermicelli Pasta formed into very long, thin strands. Vermouths Aperitifs based on wines flavoured with herbs and spices, including wormwood flowers (Artemisia absinthium). Vernonia Genus of plants producing a seed oil rich in vernolic acid and containing triacylglycerols with epoxidized fatty acid moieties. Vero cytotoxins Alternative term for verotoxins and Shiga like toxins. So called because of their cy- totoxic activity in African Green Monkey Kidney (Vero) cells. Verotoxins Cytotoxins produced by enterohaemor- rhagic Escherichia coli strains, which are similar to Shiga toxins. Alternative term for Vero cytotoxins and Shiga like toxins. Verrucosidin Potent neurotoxin produced by Peni- cillium spp., such as P. polonicum and P. aurantiogri- seum, particularly on meat products including sau- sages and dry cured ham . Verruculogen Tremorgenic mycotoxin produced by species of Penicillium, Neosartorya fischeri and Aspergillus fumigatus, fungi responsible for spoil- age of foods. Versicolorin Precursors in the aflatoxin B 1 biosyn- thesis pathway in fungi. Occur as versicolorin A and versicolorin B. Verticillium Genus of mitosporic fungi of the order Hypocreales and class Sordariomycetes. Commonly isolated from soil and decaying vegetation. May be re- sponsible for plant diseases and food spoilage. Vetch seeds Seeds produced by plants of the genus Vicia, especially V. sativa, common vetch. High in protein, making them a popular feed for ruminants. Resemble lentils when split, making them a potential low cost substitute for lentils in human nutrition. How- ever, there is concern over toxicity to monogastric species due to the presence of neurotoxins such as Ȗ- glutamyl-ȕ-cyanoalanine and other precursors of cya- nide formation. Toxins may be removed by appropri- ate steeping and cooking procedures. Veterinary inspection Governmental surveillance of food producing animals to ensure a clean, wholesome, disease-free meat supply that is without adulteration. There are approximately 70 diseases that animals can transmit to man; for this reason, inspections are made by veterinarians at places of animal slaughter and at meat processing facilities. Viability Capacity of cells for survival. Use of micro- biological techniques which differentiate between viable and dead microorganisms in foods may give a more accurate estimation of the risk of foodborne diseases. Vibrio Genus of Gram negative, facultatively anaero- bic, straight or curved rod-shaped bacteria of the family Vibrionaceae. Occur in freshwater and marine habitats. Vibrio cholerae is the causative agent of cholera, which is often transmitted via contaminated foods (e.g. shellfish) and water. V. parahaemolyticus and V. vulnificus are responsible for gastroenteritis, and are often transmitted via contaminated shellfish. Vicilin One of the main storage proteins of leg- umes. Vicine Antinutritional glycoside present in faba beans that can cause favism (haemolytic anaemia), thus limiting the nutritional value of these beans. Video image analysis Computer-aided technique in which photographic images of a sample are analysed to give information about particle structure and disper- sion. Vienna sausages Small, cooked, smoked sausages often served as an hors d'oeuvre; they take their name from the city of Vienna, Austria. Traditional, Vienna sausages are twisted into a chain of links. More com- monly, however, they are open-ended sausages, which are canned in brine. Vilia Finnish fermented milk. Vinasse Liquid wastes remaining in the still after fermentation of beverages such as wines in the manufacture of spirits. Vinclozolin Dicarboximide non-systemic fungicide. Classified by WHO as unlikely to present acute hazard in normal use. Vinegar Fermented condiment that is essentially a solution of t4% acetic acid. The word is derived from the French, meaning sour wine, as vinegar was originally produced as an unwanted by-product of 444 Vine leaves Viscometers winemaking. Several types of vinegar with character- istic flavour profiles are produced by fermentation of various substrates, including apples, cider, grape musts, wines and malt. Vinegar fermentation is a 2- stage process. The initial alcoholic fermentation of sugars in the chosen substrate is carried out by Sac- charomyces spp., while the acetic fermentation of the alcohol produced to acetic acid is carried out by acetic acid bacteria in the presence of O 2 . Due to the acidic nature of vinegar, it is also used in acidu- lants and preservatives. Vine leaves Leaves of grape vines used to wrap foods prior to cooking, as in dolmades. Also used in salads and garnishes. Available fresh or canned in brines. Vines Plants of the genus Vitis, generally V. vinifera, which produce grapes. The leaves of the plants are also eaten, being used to wrap foods prior to cooking, as in dolmades, and also eaten in salads and gar- nishes. Viniculture Alternative term for viticulture. Vinification Alternative term for winemaking. Vintage Describes the year and vineyard or geo- graphical origin of a grape harvest and the wines made from these grapes. A blend of winemaking grapes taken from 2 or more years yields a wine that is called non-vintage. Some vintages are considered better than others depending on the quality of the har- vest in that year. Vinyl chloride Flammable, possibly carcinogenic, gas which is polymerized to make polyvinyl chloride. Also used as a propellant in aerosols. Synonym chloroethene. Vinylidene chloride Colourless liquid which is po- lymerized to make the thermoplastic material polyvi- nylidene chloride (PVDC). Synonym 1,1- dichloroethene. Violaxanthin Xanthophyll carotenoid pigment found in algae and certain fruits, e.g. kiwifruit, olives, grapes and mangoes. Viomellein Mycotoxin produced by species of As- pergillus and Penicillium. May be synthesized in stored cereals contaminated with these fungi. Vioxan A preparation of the insecticide carbaryl. Virginiamycin Cyclic polypeptide antibiotic complex produced by Streptomyces virginiae . Consists of 2 major components: virginiamycin factors M1 and S1. Member of the streptogramin class of antibiotics. Has been used to treat infections with Gram positive bacteria and as growth promoters in cattle, sheep, swine and poultry. Has also been used to increase production of eggs in hens. Not significantly absorbed by treated animals and residues in edible tissues are normally not detected. However, now banned for use in food producing animals in many countries worldwide due to evidence for emergence of resistant bacteria in humans and animals following an- tibiotic use, the spread of resistant animal bacteria to humans, the transfer of antibiotics resistance genes from animal bacteria to human pathogens, and resistant strains of animal bacteria causing human dis- ease. This leaves human infections untreatable by anti- biotics from the same class as virginiamycin. Viridicatin Mycotoxin produced by fungi of the genus Penicillium, including P. cyclopium and P. discolor. Strains producing the toxin have been isolated from a wide range of food types. Viridicatol Mycotoxin produced by fungi of the genus Penicillium, including P. cyclopium and P. discolor. Strains producing the toxin have been isolated from a wide range of food types. Viriditoxin Teratogenic mycotoxin produced by some species of Aspergillus, including A. fumigatus and A. viridinutans, and also by Paecilomyces variotii. Strains producing the toxin have been isolated from a range of agricultural commodities. Virulence The degree of pathogenicity of groups of microorganisms and their relative ability to cause diseases. Intrinsic properties of pathogens (viru- lence factors) contribute to their pathogenic capac- ity. Virulence factors Properties of, or substances pro- duced by, pathogens that determine their capacity to cause disease (virulence). Include adherence, colonization, invasion, toxins, motility, chemo- taxis, microbial proteins, flagella, pili and host im- mune response inhibitors. Viruses Non-cellular microorganisms that consist of a core of RNA or DNA enclosed in a protein coat (capsid) and, in some forms, a protective outer mem- brane (viral envelope). Can live and reproduce only in susceptible living microbial, plant, human and animal host cells. Causative agents of many important dis- eases of humans, animals and plants. Viscera Soft internal organs of the body, usually those contained in the abdominal cavity. In animals, fish and birds processed for food, the viscera (removed by evisceration or gutting) are often discarded as waste products. However, fish processing wastes have shown potential for recovery of lipids and pro- teins. Viscoelasticity Rheological properties relating to the reaction of a product to a stress or strain, consisting partly of a viscous element and partly of an elastic one. Viscometers Instruments for measuring the viscos- ity of liquids. Also called viscosimeters. 445 Viscometry Vitamin D Viscometry Measurement of viscosity of a liquid, usually performed with viscometers. Viscosity Measure of the ease with which a fluid can flow when subjected to shear stress, measured in Newton seconds per square metre or Pascal seconds. Low viscosity, e.g. that of a gas, allows flow through a fine tube to be quite rapid, whereas high viscosity (as with thick oils) makes motion sluggish. Viscosity arises from the intermolecular forces in a fluid (inter- nal friction); the stronger these forces, the greater the viscosity. With a rise in temperature, attraction be- tween the molecules is reduced, enabling them to move more freely. Vision systems Systems of visual feedback based on various devices, such as video cameras, photo cells, or other apparatus, allowing a robot to recognize objects or measure their characteristics. Vision systems are widely employed in quality control processes in the food industry. Vital gluten Wheat protein complex separated from starch in a wheat flour dough and dried. Used to improve strength of bread dough. Vitamers Group of compounds varying in structure but displaying qualitatively similar biological activities with respect to specific vitamins. Collectively re- ferred to by the name of the vitamin involved. Vitamin A Group of fat-soluble compounds (reti- noids) which exist in several isomeric forms and oc- cur preformed only in foods of animal origin. The two vitamin A forms are: retinols, which predominate in mammals and marine fish; and dehydroretinols, which predominate in freshwater fish. Vitamin A is present in yellow and green leafy plants as provita- min A, of which there are several forms. The most important ones in human nutrition are the carote- noids, Į- and ȕ-carotene and cryptoxanthin. These are converted to the active vitamin in the intestinal wall and liver. Richest sources of preformed retinols are fish liver oils, egg yolks and fortified milk. Biologically active carotenoids are found in dark green leafy vegetables and yellow fruits and vegeta- bles, such as squashes and carrots. In humans, common signs of vitamin A deficiency are poor growth, lowered resistance to infection, night blindness and rough scaly skin. Severe deficiency leads to kera- tomalacia and xerophthalmia. Vitamin antagonists Antinutritional factors which are present in some natural foods and do not function as vitamins , even though they are chemi- cally related to them. As a result, they cause vitamin deficiencies where the body is unable to distinguish them from true vitamins, and incorporates them into essential body compounds. Vitamin B 1 Former name for thiamin. Vitamin B 12 Synonym for cyanocobalamin. Mem- ber of the vitamin B group, found in foods of animal origin such as livers, fish and eggs. Vitamin B 12 is the coenzyme for methionine synthase (EC 2.1.1.13), an enzyme important for the metabolism of folic acid, and methylmalonyl coenzyme A mutase (EC 5.4.99.2). Absorption of this vitamin requires the presence of an intrinsic factor. Failure of absorption, rather than dietary deficiency, is the major cause of pernicious anaemia. Vitamin B 13 Synonym for orotic acid. An intermedi- ate in the biosynthesis of pyrimidines, and growth factor for some microorganisms. Vitamin B 2 Former name for riboflavin. Vitamin B 6 Vitamin which exists in three forms - pyridoxine (the alcohol form), pyridoxal (the alde- hyde form) and pyridoxamine (the amine form). The relative proportion of each of the three forms in foods varies considerably. All are equally biologically active. Vitamin B complex Alternative term for vitamin B group. Vitamin B group Group of water soluble vitamins generally found together in nature and basically related in function, although unrelated chemically. These in- clude vitamin B 1 (thiamin), vitamin B 2 (ribofla- vin) the vitamin B 6 group (pyridoxine, pyridoxal and pyridoxamine), the vitamin B 12 group (the co- balamins), nicotinic acid (niacin), folic acid (pteroylglutamic acid), pantothenic acid and bio- tin. Vitamin C Synonym for ascorbic acid, an antioxi- dant nutrient present in a wide range of foods. Neces- sary for growth of bones and teeth, for maintenance of blood vessel walls and subcutaneous tissues, and for wound healing; dietary deficiency results in scurvy. Used in food additives, with applications in food antioxidants and bakery additives. Vitamin D Group of several related sterols exhibiting qualitatively the biological activity of calciol (chole- calciferol). The most important members are vita- min D 2 (ergocalciferol or calciferol) and vitamin D 3 (cholecalciferol). The former is synthesized by ir- radiation of the plant provitamin ergosterol, and the latter is produced from the provitamin 7- dehydrocholesterol (found underneath the skin) on ex- posure to UV light from the sun. Vitamin D is also considered to be a prohormone. Fish liver oils and foods fortified with vitamin D are the major dietary sources; smaller amounts are found in livers, egg yolks, sardine and salmon. Severe deficiency in children results in rickets; deficiency in adults leads to osteomalacia. 446 Vitamin D2 Vodka Vitamin D 2 Synonym for calciferol and ergocalcif- erol; one of the group of sterols which constitute vi- tamin D. Synthesized by irradiation of the plant provitamin ergosterol. Vitamin D 3 Synonym for cholecalciferol; one of the group of sterols which constitute vitamin D. Fat- soluble vitamin necessary for formation of the skeleton and for mineral homeostasis. Produced on exposure to UV light from the sun from the provitamin 7- dehydrocholesterol, which is found in human skin. Vitamin E Fat-soluble vitamin comprising compounds which exhibit qualitatively the biological activity of Į- tocopherol. Two main groups of compounds have vitamin E activity - tocopherols and tocotrienol. There are 4 isomers of each: Į-, ȕ-, Ȗ- and į- tocopherols; and Į-, ȕ-, Ȗ- and į-tocotrienols. Each has differing vitamin potency. Vitamin E functions primar- ily as an antioxidant in cell membranes, protecting unsaturated fatty acids from oxidative damage. Vitamin E contents of foods are expressed as mg Į- tocopherol equivalent; leafy vegetables, seeds and most vegetable oils are good sources. Vitamin E acetate Esterified form of vitamin E which has no antioxidative activity until the acetate is removed in the intestine as it is absorbed. The ace- tate form is more stable with respect to storage time and temperature than unesterified forms. Vitamin F Obsolete name for thiamin. Vitamin G Obsolete name for riboflavin. Vitamin H Obsolete name for biotin. Vitamin K Group of fat-soluble vitamins essential for production of prothrombin and several other proteins involved in the blood clotting system, and the bone protein osteocalcin. Deficiency causes impaired blood coagulation and haemorrhage; vitamin K is sometimes called the antihaemorrhagic vitamin. Two groups of compounds have vitamin K activity: phylloquinone, found in all green plants; and a variety of menaquinones synthesized by intestinal bacteria. Dietary deficiency is unknown, except when associated with general malabsorption diseases. Vitamin K 1 Synonym for phylloquinone. Fat-soluble vitamins found in all green plants. Especially abun- dant in alfalfa and green leafy vegetables. Essential for production of prothrombin, and several other pro- teins involved in the blood clotting system, and the bone protein osteocalcin. Deficiency causes impaired blood coagulation and haemorrhage. Vitamin K 3 Synonym for menadione. Synthetic com- pound with vitamin K activity, used in prevention and treatment of hypoprothrombinaemia, secondary to fac- tors that limit absorption or synthesis of vitamin K. Two to three times more potent than naturally occur- ring vitamin K. Vitamin K 2 series Synonym for menaquinones. Variety of metabolites with vitamin K activity syn- thesized mainly by intestinal bacteria. Also found in meat, livers, eggs and cheese. Formerly called farnoquinone. Vitamin P Group of plant bioflavonoids, including rutin, naringin, hesperidin, eriodictin and citrin, which affect the strength of capillaries in the body. Bioflavonoids are found as natural pigments in vegetables, fruits and cereals. In addition to their effect on capillary fragility, it is claimed that biofla- vonoids function as follows: they are active antioxida- tive compounds in foods; they possess a metal- chelating capacity; they have a synergistic effect on ascorbic acid; they possess bacteriostatic and/or an- tibiotic activity; and they possess anticarcinogenic ac- tivity. Vitamin PP Obsolete name for niacin. Vitamins Groups of nutrients which are essential in small amounts for most living organisms to maintain normal health and development. Vitamin U Synonym for S-methylmethionine. A compound found in raw cabbages, other green vegetables, beer and citrus juices. Thought to as- sist in healing of skin ulcers and ulcers in the digestive tract; also has an effect on secretory, acid-forming and enzymic functions of the intestinal tract. Viticulture Cultivation of vines for production of winemaking grapes or table grapes. Vitreosity Extent to which a substance resembles glass with respect to properties such as hardness, brittleness, transparency and structure. Vitrification Phenomenon whereby a substance is cooled rapidly to a low temperature such that the water it contains forms a glass-like solid without undergoing crystallization. The temperature at which the transi- tion into a glassy solid occurs is the glass transition temp. Glass formation can result in stabilization of non-equilibrium systems, including most foods. In the glassy state, physicochemical deterioration is inhibited, effectively preserving the system. Vitrification tem- perature can be used as an indicator of food safety and storage stability. Vla Dutch custard-type viscous dairy dessert made with milk, carrageenans, modified starches and fla- vourings. Vodka Spirits, originating in Russia and northeast Europe, made from grain or potatoes. Generally rec- tified to have neutral flavour and aroma, but some types contain added flavourings. 447 Volatile compounds Vomitoxin Volatile compounds Compounds that are readily vaporized. Often have a characteristic aroma and are therefore often flavour compounds and aroma compounds. Volatile fatty acids Fatty acids that, apart from being present in some foods, are produced by bacte- ria in the human intestine and the rumen of cattle from undigested starch and dietary fibre. To some extent, they can be absorbed and used as a source of energy. Volatile fatty acids formed in the colon may show an- ticarcinogenicity. Volatile organic compounds Non-methane hy- drocarbons produced as industrial pollutants. Volatile sulfur compounds Sulfur-containing fla- vour compounds found in garlic (e.g. methyl mercaptan, allyl mercaptan), onions, Brassica spp. such as cabbages, cauliflowers and broccoli, wines and fruit juices. Some compounds can cause an off odour in wines, e.g. H 2 S can lead to a rotten egg odour. However, other compounds improve wine aroma, e.g. 3-mercaptoethanol enhances fruitiness. Voltammetry Electrochemical technique in which the relationship between voltage and current flowing be- tween electrodes in a reaction solution is measured. Utilizes a working electrode, where the reaction oc- curs, an auxiliary electrode for current flow and a ref- erence electrode that is used to measure the potential of the working electrode. Volumetric analysis Titration technique based on measurement of the volume of reagent required to re- act completely with the analyte. Volvariella Genus of edible fungi that include padi straw mushrooms (Volvariella volvacea) and straw mushrooms (V. diplasia). Another widely consumed species is V. speciosa, easily confused with some poisonous Amanita spp. Volvatoxins Cardiotoxic proteins produced by Vol- variella volvacea (straw mushrooms). Exist as volva- toxin A1 and volvatoxin A2. Vomitoxin Synonym for deoxynivalenol. A tricho- thecene produced by Fusarium spp. W Wafers Light, thin, crisp biscuits served as an ac- companiment to desserts or ice cream, or eaten sandwiched together with sweet or savoury fillings or coated with chocolate. Waffles Light, crisp, indented raised cakes leavened with baking powders or yeasts and typically baked in a special waffle iron, which cooks both sides simul- taneously. Often consumed as a breakfast food, ac- companied by maple syrups. May also be eaten as desserts, topped with cream or ice cream. Wakame Common name for Undaria pinatifida, one of the the brown seaweeds. Used in soups and also consumed as a toasted, sugar-coated and canned prod- uct. Alternative spelling is wakami. Wakami Alternative spelling of wakame; one of the brown seaweeds in the genus Undaria. Wallemia sebi Species of xerophilic spoilage fungi of the order Wallemiales. Causes spoilage of fruits, cereal products, syrups and jams. Walleye Freshwater fish species (Stizostedion vitreum) belonging to the family Percidae; distributed across North America. Flesh is highly esteemed for its flavour and texture. Cultured in some parts of North America. Marketed fresh and frozen. Walleye pollack Alternative term for Alaska pol- lack. Walnut oils Relatively expensive oils extracted from walnuts. The distinctive nutty flavour and aroma make them popular for use in salad dressings, driz- zling on to cooked foods and in cooking. Sometimes used as an alternative to olive oils. To prevent devel- opment of rancidity, walnut oils are best stored in a cool, dry location, out of direct sunlight. Walnuts Nuts produced by trees of the genus Juglans, the most economically important species being J. regia (common or Persian walnuts), J. nigra (black walnuts) and J. cinerea (butternuts or white walnuts). Ripe nuts are rich in vitamin E and B group vitamins, while younger fruits also contain vitamin C. Used as dessert nuts, and as ingredients in confectionery, bakery products and ice cream. Oils extracted from the nuts contain a high proportion of unsatu- rated fatty acids and have a range of food uses. Walruses Large, carnivorous marine mammals (Odo- benus rosmarus) belonging to the family Odobenidae in the order Pinnipedia. They are hunted for their meat, particularly by the northern Inuit and Indian communities in the Canadian Arctic and northern coastal British Columbia regions. Characteristics of walrus meat include: a high content of protein, with a biological value similar to that of beef; a darker col- our than beef; and a distinctive flavour. Walrus blubber forms a part of traditional diets in some ar- eas, but may be associated with health risks due to bioaccumulation of organochlorine pesticides and other contaminants. In Arctic regions, trichi- nosis is commonly associated with consumption of raw or inadequately cooked walrus meat. Warehouses Large buildings in which raw materials or manufactured goods are stored. Warmed over flavour Characteristic off flavour primarily associated with cooked meat and poultry meat in chilled ready meals and other cook chill foods. In cooked meat and poultry held at chilled storage temperatures, this stale, oxidized flavour be- comes apparent within a short time (48 hours), particu- larly if the product is stored under air. Modified at- mosphere packaging under low oxygen levels helps to delay the onset of oxidative warmed over fla- vour. Warming The process by which an item is heated slightly to the point of being warm. Wasabi Pungent spices produced from the roots of Wasabia japonica. Used most commonly in Japanese cuisine and for flavouring of condiments. Also known as Japanese horseradish. Wastes Unusable, unwanted or discarded materials. In the food industry, wastes can result from application of processing procedures, and consist of solids such as pomaces, feathers and sludges. By recycling, some materials in wastes can be reclaimed for further use. Waste water Unusable, discarded water (effluents) resulting from processing procedures. In the food in- dustry, waste water is commonly produced by brew- eries, dairies, distilleries, olive oil mills and palm 449 Water Water supplies oil mills. Must be disposed of safely, often after treat- ment, to minimize pollution. Water Colourless, odourless and tasteless liquid with the chemical formula H 2 O, which is essential for plant and animal survival. Widely drunk as a beverage, usu- ally after some form of disinfection. Used in the food and beverage industries in many ways, including as an ingredient, in the form of process water, and in cooling and heating systems. Water activity Measure of the water vapour gener- ated by the moisture present in a hygroscopic product. Defined as the ratio of the partial pressure of water va- pour to the partial pressure of water vapour above pure water at the same temperature. In foods, it represents water not bound to food molecules; the level of un- bound water has marked effects on the chemical, microbiological and enzymic stability of foods. Com- monly abbreviated to a w . Water binding capacity Extent to which a substance can bind water. Water chestnuts Seeds of Trapa natans or T. bicor- nis, which are cooked and eaten as vegetables. Commonly used in Chinese cooking. Water convolvulus Common name for Ipomoea aquatica, a plant grown in China, Taiwan and Viet- nam, also known as water spinach. Stems and leaves are eaten as vegetables, either boiled or stir fried; stems are also used as ingredients in pickles. Watercore Internal defect that affects mainly apples, but also pears and sometimes other fruits. Character- ized by water-soaked appearance of some or all of the flesh. Watercress Dark green leafy plant (Nasturtium offici- nale or N. microphyllum x officinale). Rich in proteins, iron, carotenes and vitamin C; also contains vita- min E, group B vitamins and other minerals. Used in salads, garnishes, soups and cooked as a vegetable. Water dropwort Common name for Oenanthe stolo- nifera. Young shoots and leaves from the plant are used in China as flavourings for fish soups and poultry dishes. Waterfowl Wetland birds such as ducks, geese and swans, which belong to the order Anseriformes. The term is most commonly used for wetland game birds, some of which are hunted for their meat. Water hardness A measure of the amount of dis- solved mineral salts, especially calcium and mag- nesium salts, in water, including drinking water. Hard water has a high content of dissolved minerals, while soft water has a low mineral content. Water hardness is an important factor in food processing since it can affect product quality. Water holding capacity Extent to which a substance can hold and retain water. Related to the solubility of the sample. Water ices Frozen sugar confectionery made from water and sugar and flavoured with fruit juices, fruit purees or other fruit flavourings. Used to make some types of ice lollies. Wateriness One of the sensory properties; relat- ing to the extent to which a product is watery, i.e. runny and wet. Watermelon juices Juice extracted from watermel- ons. Contains high levels of lycopene, vitamin A, vitamin C, potassium, magnesium and the amino acid citrulline, which is claimed to have performance- enhancing effects in athletes and demonstrates anti- oxidative activity and vasodilatory activity. Used as an ingredient of fruit beverages, sports drinks and some alcoholic beverages, including shots and cocktails. Watermelons Large globose or oblong fruits pro- duced by Citrullus lanatus or C. vulgaris. Good source of vitamin A and vitamin C. Colour of rind and flesh varies according to variety. Flesh contains nu- merous seeds that are rich in proteins and oils, and can be eaten dry or roasted. Watermelon seeds Seeds from watermelons of the genus Citrullus. Mature seeds are roasted and salted for consumption as snack foods and have po- tential use as oilseeds. Water pollution Contamination of water resources with substances (usually toxic chemicals or waste mat- ter) which can be harmful to organisms living in the water, or to those that drink it or are otherwise exposed to it. Water sorption Attachment of water onto the surface or into the body of a material. Water spinach Common name for Ipomoea aquatica, a plant native to India and South East Asia but grown widely in other regions. Due to its invasive and aggres- sive nature, the plant poses a serious threat to water- ways in the southern USA and is considered a noxious weed. Stems and leaves are eaten as a vegetable, often stir fried. Rich in proteins and minerals, especially iron. Alternative names include swamp cabbage and water convolvulus. Water stress Condition caused in plants by lack of sufficient water for growth, as in drought. Can have adverse effects on growth and quality of edible plant parts, e.g. fruits and leaves. Water supplies Drinking water supplied to the public and industry by a water supply company or au- thority. [...]... endo-1, 3- -xylosidases EC 3.2.1.32 Xylan degrading enzymes that catalyse the random hydrolysis of 1, 3- -D-xylosidic linkages in 1, 3- -Dxylans Useful as dough improvers and volumeincreasing agents in bread and bakery products, and for wheat starch separation Also known as xylanases and endo-1, 3- -xylanases Xylan 1, 4- -xylosidases EC 3.2.1.37 Xylan degrading enzymes that hydrolyse 1, 4- -D-xylans, removing... the bulk of the hemicelluloses component Consists of (1 4 )- -linked D-xylose residues with side chains of other sugars, such as (4-O-methyl)-D-glucopyranosyluronic acid and -Larabinofuranosyl residues (1 3)-linkages may also be present and the molecule may be acetylated Xylanases Alternative term for xylan degrading enzymes and xylan endo-1, 3- -xylosidases Xylose isomerases Xylan degrading enzymes General... penetrating power Longer wavelengths, near the UV-ray band of the electromagnetic spectrum, are known as soft X-rays The shorter wavelengths, closer to and overlapping the gamma-ray range, are called hard X-rays A mixture of many different wavelengths is known as white X-rays, as opposed to monochromatic X-rays, which represent only a single wavelength X-rays are used in the food industry for a wide... X-ray photon and fluorescence, which is measured using a spectrophotometer X-rays Penetrating electromagnetic radiation of very short wavelength, able to pass through many materials X-rays are produced by bombarding a target, usually made of tungsten, with high-speed electrons The shorter the wavelength of the X-ray, the greater is its energy and its penetrating power Longer wavelengths, near the UV-ray... isomerization of D-xylose and D-xylulose Also isomerize D-ribose and D-glucose, and are useful for isomerization of glucose to fructose in the pro- Xylose reductases 458 duction of fructose high corn syrups The name glucose isomerases is still widely used for these enzymes Xylose reductases Alternative term for aldehyde reductases -Xylosidases xylosidases Alternative term for xylan 1, 4- - Xylulose Ketose... the smoke and governs its application Used in flavourings and/or preservatives Foods which are commonly processed using smoke include fish and meat Smoke flavourings may be added to barbecue sauces or marinades Woolliness Extent to which products, usually fruits, have a woolly texture, i.e are dry and spongy Woolliness is an adverse sensory property and physiological disorder, involving lack of juiciness,... lumpier texture can be given to encourage chewing (mastication) Weevils Common name for various insects of the family Curculionidae Also known as snout beetles Often highly destructive pests of crops and stored cereal grains, e.g the alfalfa weevil (Hypera postica), the grain weevil (Sitophilus granarius) and the rice weevil (S oryzae) Larvae of some species can be destructive to fruits, nuts and grain... an isomer of xylose May be d-Xylulose reductases formed by aldose-ketose isomerization of xylose using bacterial xylose isomerases D-Xylulose reductases EC 1.1.1.9 Dehydrogenases involved in the fermentation of xylose and production of xylulose from xylitol These enzymes have been expressed in several bacteria, and the yeast Saccharomyces cerevisiae, and recombinant cells have been used for fermentation... name for Artemesia absinthium, leaves and flowering tops of which are used to produce spices Wormwood has a bitter flavour It is used in natural flavourings for vermouths A absinthium extracts and essential oils are also used as flavourings The plant also contains -thujone, which is a convulsant at high concentrations; hence, in some countries such as the USA, foods and beverages containing wormwood are... the analytical techniques employed for analysis of bone mineral X-ray crystallography 457 density, body composition and obesity It is more commonly known as dual energy X-ray absorptiometry since it involves irradiation with 2 beams of X-rays having different energies The amount of X-ray radiation absorbed by a tissue is correlated positively with its density Used in nutritional studies for assessing . produced by Vol- variella volvacea (straw mushrooms). Exist as volva- toxin A1 and volvatoxin A2. Vomitoxin Synonym for deoxynivalenol. A tricho- thecene. xy- lanases and endo-1, 3- -xylanases. Xylan 1, 4- -xylosidases EC 3.2.1.37. Xylan de- grading enzymes that hydrolyse 1, 4- - D -xylans, removing successive