Từ điển công nghệ thực phẩm - G

G Galactanases Common term for arabinogalactan endo-1,4-ȕ-galactosidases (EC 3.2.1.89), enzymes that catalyse the endohydrolysis of 1,4- D -galactosidic linkages in arabinogalactans. Can be used for pro- duction of galactooligosaccharides by virtue of their transglycosylation activity. Galactans Galactose polymers found in agar, car- rageenans, pectins and hemicelluloses. Com- plete hydrolysis of galactans results in the production of galactose only, whilst incomplete hydrolysis gener- ates galactooligosaccharides. Galactitol Polyol comprising six carbon atoms, pro- duced by isomerization of sorbitol. Has approxi- mately 10% the sweetness of sucrose. Also known as dulcitol due to its presence in dulcite (Madagascan manna, Melampyrum nemorosum). Galactolipids Glycolipids which contain galac- tose residues and/or N-acetylgalactosamine. Found in nervous tissue and plant membrane lipids. Include cer- tain cerebrosides. Galactomannans Polymers of D -galactose and D - mannose found in bacteria, yeasts and legumes, possibly as storage polysaccharides. Galactooligosaccharides Oligosaccharides that consist mainly of galactose residues. Produced by action of ȕ-galactosidases on lactose. Present naturally in human milk and thought to be the main carbon source for Bifidobacterium in the neonatal gastrointestinal tract. Added as prebiotics to in- fant formulas and probiotic foods, e.g. fer- mented milk and yoghurt. Have approximately 0.2 times the sweetness of sucrose and are useful in food processing as they have greater thermal stabil- ity and acid resistance than sucrose. For this reason, they have been included in jams and bread. Galactosamine Derivative of galactose in which the hydroxyl group of the carbon-2 atom is replaced by an amino group. Found in glycolipids, mucopoly- saccharides and chondroitin sulfate. Galactose Monosaccharide with six carbon atoms which occurs naturally as a component of many com- plex plant-derived polysaccharides, such as pectins and gums. Constituent of lactose, from which it may be produced by hydrolysis. Has approxi- mately 40% the sweetness of sucrose and is used in sweeteners. Galactosidases Glycosidases in EC 3.2.1 com- prising Į-galactosidases, ȕ-galactosidases and galactanases. Į-Galactosidases EC 3.2.1.22. Glycosidases which hydrolyse terminal, non-reducing Į- D -galactose residues in Į- D -galactosides, including galactose oligosaccharides, galactomannans and galac- tolipids. Can also hydrolyse Į- D -fucosides. Useful for hydrolysis of raffinose oligosaccharides which are flatulence factors in legumes and their processed products, including soymilk. Also known as melibi- ases. ȕ-Galactosidases EC 3.2.1.23. Glycosidases which hydrolyse terminal non-reducing ȕ- D -galactose residues in ȕ- D -galactosides. Also catalyse transgly- cosylation reactions yielding galactooligosac- charides. Used for production of low lactose foods, where they hydrolyse lactose to glucose and galactose. These modified foods, mainly dairy products, are suitable for individuals who suffer from lactose intolerance. Lactose hydrolysates are readily soluble and can be used as syrups for the manufacture of baked goods and other foods. These enzymes are also useful for utilization of whey- containing wastes. Also known as lactases. Galactosides Glycosides formed from mixing ga- lactose with an alcohol; on hydrolysis, galactose is produced. Galacturonic acid Member of the uronic acids derived from D -galactose by oxidation of the alcohol group of the carbon-6 atom to form a carboxyl group. Found in pectins, plant gums and bacterial cell walls. Galangal Rhizomes from the zingiberaceous plant, Alpinia galanga or A. officinarum (lesser galangal). Similar to ginger, and used as a spice in South East Asia and some other regions in flavourings for prod- ucts such as curries, vinegar and wines. Also re- ported to have medicinal properties. Galgals Type of lemons produced by Citrus pseu- dolimon, which are indigenous to and cultivated on a commercial scale in India. Used in manufacture of 184 Gallic acid Garlic pickles and as a source of fruit juices, peel, pectins and essential oils. Gallic acid Also known as 3,4,5-trihydroxybenzoic acid. This organic acid has antioxidative activity, and is commonly used as a standard when measuring levels of phenols in foods and beverages. Occurs naturally as a component of tannins, e.g. in tea. Gal- lic acid esters, such as octyl gallate and propyl gallate, are used as antioxidants in the food indus- try. Gallocatechin gallate One of the catechols formed by epimerization of epigallocatechin gallate, dur- ing heating, pasteurization or autoclaving of green tea or black tea. Found in relatively high amounts in bottled or canned tea beverages. Dem- onstrates hypocholesterolaemic activity. Gallstones Solid masses or stones that occur in the gallbladder or bile ducts. They form when components of the bile precipitate out of solution and form crystals. The most common type is composed mainly of cho- lesterol. Diet is believed to have a role in gallstone formation. Game The collective name for birds and animals which normally live in the wild and are hunted for sport or game meat. In many countries, game may only be killed by people possessing a Game Licence and a licence is also needed to sell game. Legislation may also specify close seasons when game must not be shot or open seasons when particular types of game may be shot. Game is regarded as a valuable asset on many farms. If wild game is managed carefully, it is possible to produce a regular crop of game birds and animals which can be culled to provide game meat. A high level of consumer demand for game meat has led to farming, including ranch-raising, of wild game; for example, red deer have been farmed successfully in Scotland, elands in Zimbabwe and reindeer in the north of Scandinavia. The majority of commercially available game meat is from farmed game. Game birds Heavy bodied, ground-nesting birds which are farmed or hunted for their meat. They be- long to the order Galliformes and include grouse, guinea fowl, partridges, pheasants and quails. Game meat The meat of wild or farmed game (game birds or game animals). Game meat has a characteristic flavour and dark red colour. The fla- vour and aroma of game meat may be very strong; to decrease these characteristics, game meat is often marinated before cooking. Game meat tends to have a low fat content, which is attractive to consumers, but can make it difficult to cook. Meat from game animals, such as wild boars and bears, may be infested with Trichinella spiralis larvae; such meat must be cooked thoroughly to avoid the risk of trichinosis. Gamma irradiation Exposure of foods to gamma rays, generated by radioactive decay of cobalt-60 ( 60 Co) or caesium-137 ( 137 Cs). Used for sterilization or preservation purposes. Irradiation delays ripen- ing of fruits and vegetables, inhibits sprouting in bulbs and tubers, causes disinfestation of grain, cereal products, fresh and dried fruits and vegeta- bles, and destroys bacteria in fresh meat. Despite initial concerns among consumers over the safety of irradiation and irradiated foods, over 40 countries have approved the process for food use. Gamma rays Penetrating electromagnetic radiation of shorter wavelength than X-rays. For food irradia- tion, sources used for generation of gamma rays in- clude cobalt-60 ( 60 Co) and caesium-137 ( 137 Cs). Gammon The thigh and adjacent parts, including the hind leg, of a side of bacon, usually cured while still part of the swine carcass. Preparation involves brin- ing of the meat as if it were to become bacon and then draining for about one week. Some gammon is cold- smoked before being sold, whilst other gammon is un- smoked and is also known as pickled pork. Gammon is usually sold uncooked, but cut into small portions or sliced as gammon steaks. It is commonly cooked by baking or pan frying, or is cooked in a casserole with vegetables or pulses. Gangliosides Glycolipids composed of a fatty acid (most often stearic acid) and an oligosaccharide, containing hexose and sialic acid residues, attached to a sphingosine. High concentrations are found in central nervous system tissues. Ganoderma Edible fungi used in health foods and medicines, especially in China and Japan. Most com- mon example is Ganoderma lucidum. Garbanzo beans Alternative name for chick peas. Gardenia Genus of flowering plants. Fruits of Garde- nia jasminoides are used as a source of food color- ants. The colorants are primarily composed of yellow carotenoids, crocin and its congeners, and iridoid glycosides such as geniposide. Gari Meal produced by roasting and drying fermented cassava mash. Major food source in West Africa. Protein content is low. May contain potentially toxic levels of residual cyanogens, depending on the proc- essing techniques used. Garlic Pungent, edible bulbs of Allium sativum. One of the world's most widely used spices, used to flavour many different dishes. Each bulb comprises a number of cloves, which release a characteristic aroma when peeled and crushed. This aroma is due to the presence of allicin, which is believed to play a key role in the beneficial health effects reported for garlic. As well as 185 Garlic oils Geese being used fresh, much of the crop is further processed to yield garlic powder, garlic salt or garlic oils. Garlic oils Highly pungent essential oils obtained from garlic. Used in spice mixes and other flavour- ings. Major constituent is allyl sulfide. Garnishes Decorative and edible accompaniments to sweet or savoury dishes, usually added just before serving. May be placed on the plate beside the dish or applied to the surface of the food. Vary greatly in size and content, including sprigs of parsley or other herbs, salad vegetables, croutons, slices of fruit, whole fruits and chocolate shapes. Garnishes often indicate the main ingredient or flavour of a dish. Gas chromatography Chromatography tech- nique, usually abbreviated to GC, in which the sample is vaporized and injected into a carrier gas (mobile phase) that moves through a column, the inner surface of which is coated with a stationary phase. Sample components are separated on the basis of their affinity for the stationary phase, and identified by the time they are retained by the stationary phase. A range of detec- tion techniques can be used in combination with gas chromatography, including mass spectroscopy (GC-MS). Gases Substances which have no fixed shape, low density and viscosity and no fixed volume, but which will adopt the volume of the space available, irrespec- tive of the amount present. Composed of widely sepa- rated molecules which may be easily compressed and has the ability to diffuse readily. Distinct from the solid and liquid states. Gas liquid chromatography Chromatography technique in which the mobile phase is a gas and the stationary phase is a liquid adsorbed on a porous solid in a tube or on the inner surface of a capillary column. Usually abbreviated to GLC. Components of the sam- ple are partitioned between the gas and liquid phases, the rate at which they are eluted from the column de- pending on their partition coefficients. They are identi- fied by the time taken to reach the detector for the sys- tem. Gassericins Bacteriocins produced by Lactoba- cillus gasseri. Gastric cancer A form of cancer involving the un- controlled growth of abnormal cells in the stomach. Several lifestyle factors have been associated with in- creased gastric cancer risk, including high intakes of salt and smoked foods, low intakes of fruits and vegetables, cigarette smoking and overweight and obesity. Infection with Helicobacter pylori is also a major risk factor for gastric cancer development. Gastritis Inflammation of the stomach. Causes can include consumption of corrosives and irritants (such as alcoholic beverages) and infection with Helicobacter pylori. Gastroenteritis Inflammation of the mucous mem- branes of the stomach and intestines. Major causes in- clude a range of pathogens that may be ingested via contaminated foods and water supplies. These in- clude species of Salmonella, Shigella, Campylo- bacter and Vibrio, and Escherichia coli, rotavi- ruses and small round structured viruses. Gastrointestinal tract The organ commencing at the mouth and finishing at the anus, including the stomach and intestines, into which foods are taken and digested, and from which nutrients and non-nutrients are ab- sorbed into the body, and waste is excreted. Gastropods Common name for molluscs within the class Gastropoda; characterized by a single muscular foot. Includes snails (aquatic and marine), limpets and sea slugs. Gateaux French word for cakes. Can refer to plain or fancy cakes, e.g. made from layers of sponge cakes filled and topped with fruits, jelly or cream. GATT Abbreviation for General Agreement on Trade and Tariffs. Gauges Instruments that measure and give a visual display of amounts, levels or contents. Gayal meat Meat from gayals, which are a type of semi-domesticated oxen. Gayals Large, semi-domesticated oxen found in In- dia. Semi-domesticated form of the gaur (Bos gaurus) that is sometimes classified as Bos frontalis. Raised for their meat and milk. Bulls are crossed with English cattle breeds to produce good quality beef cattle. Gazelle meat Meat from gazelles, which include several species of small, slender antelope, many of which belong to the genera Gazella of the family Bo- vidae. The meat is usually obtained from wild game animals and is appreciated for its tenderness. Gazelles Any of several species of small, slender an- telopes , many of which belong to the genus Gazella of the family Bovidae. Found wild in Africa, the Mid- dle East and Asia. Source of gazelle meat. Gbure Common name for Talinum triangulare, a leafy vegetable consumed in West and Central Africa. High in fibre and rich in essential amino acids. GC Abbreviation for gas chromatography. GC-MS Abbreviation for gas chromatography combined with mass spectroscopy. Geese The common name for any of numerous do- mesticated or wild waterfowl belonging to the family Anatidae, in which they comprise several genera (e.g. Anser and Branta). Most domesticated geese are kept in small flocks under free-range conditions for produc- tion of goose eggs and goose meat. A male goose 186 Gelatin Gene-nutrient interactions is called a gander, whilst the female is a goose and the sexually immature young (with down rather than feathers) is a gosling. Gelatin Soluble protein extracted from animal colla- gen, bones or connective tissues using hot water and acid or alkaline treatment. Widely used in the food industry in gelling agents, e.g. in aspic, jellies, ice cream, yoghurt and canned meat, and can also act as emulsifiers or stabilizers, e.g. in marsh- mallows and confectionery fillings. Lacks the es- sential amino acid tryptophan, but is a source of sev- eral other amino acids. Alternatively spelled gela- tine. Gelatinization Process involving disruption of mo- lecular order within starch granules as a result of heating in water. Occurs over a temperature range and is also affected by granule size. Alterations caused in- clude irreversible swelling, loss of birefringence, leaching of amylose and reduced crystallinity. Pro- longed heating of the starch granules will eventually lead to total disruption. Gelation Process of gels formation by coagulation of sols or aggregation of particles. Formed in a vari- ety of ways according to the type of material con- cerned. In the case of polymer molecules, gelation is caused by formation of intermolecular crosslinks dur- ing heating or cooling. Aggregation of particles may be induced by a variety of stimuli including changes in pH or ionic strength. Also called gelling. Gel electrophoresis Electrophoresis technique in which separation is performed in a gel, usually com- prising agarose or polyacrylamide. Gel filtration Size exclusion chromatography technique in which separation is based on the hydro- dynamic volume of molecules. Samples are applied to a column of gel, e.g. polyacrylamides, cross-linked dextrans or large polysaccharides, and components are separated on the basis of their ability to penetrate the pores of the gel beads while being washed through with an aqueous mobile phase. May be used for the fractionation of proteins and other water-soluble polymers, and determination of molecular weight. Gelidium Genus of red seaweeds known as onigusa in Japan. Eaten in some Asian countries, also a source of agar. Gellan Exopolysaccharide produced by Sphingomo- nas paucimobilis ATCC 31461 (formerly Pseudomo- nas elodea ) which is composed of a tetrasaccharide re- peating unit comprising glucose, rhamnose and glucuronic acid in the ratio 2:1:1, and with acyl sub- stitution of one of the glucose residues. Forms gels in the presence of cations and used as gelling agents and thickeners in foods. Gellan gums Gums containing gellan, a microbial polysaccharide produced by Sphingomonas pauci- mobilis ATCC 31461 (formerly Pseudomonas elodea), which form transparent and heat- or acid-resistant gels. Widely used as thickeners and gelling agents in foods. Gelling Alternative term for gelation. Gelling agents Additives used to promote gela- tion. Used in manufacture of jellies and other food gels. Commonly used gelling agents include pectins, agar, guar gums and gellan gums. Gelling capacity One of the functional properties of a substance concerned with its ability to form a gel. Gel permeation chromatography Size exclu- sion chromatography technique in which separa- tion is based on the hydrodynamic volume of mole- cules. Samples are applied to a column of gel, e.g. polyacrylamides, cross-linked dextrans or large poly- saccharides, and components are separated on the basis of their ability to penetrate the pores of the gel beads while being washed through with an organic mobile phase. May be used to analyse the molecular weight distribution and polydispersity index of organic- soluble polymers. Gels Solid or semi-solid jelly-like colloids, such as those formed when gelatin is mixed with hot water and allowed to cool. Products such as pectins and agar are well known for their gel-forming ability. Gels, including agar gels , are widely used as food stabilizers and thickeners. Gene cloning Insertion of DNA sequences containing genes into vectors (e.g. plasmids or viruses ) that can then be propagated in a host organism, thus pro- ducing multiple copies of the gene of interest. Gene disruption Use of both in vitro and in vivo recombination to replace wild type genes or DNA se- quences with a mutant version. Gene expression The process by which proteins are produced from their coding genes by means of transcription followed by translation. Gene libraries Collections of cloned DNA fragments in which the inserted sequences together represent en- tire genomes of organisms (genomic libraries). Al- ternatively, the cloned DNA may be composed of cDNA molecules formed from an mRNA template (cDNA libraries), thus representing only the expressed portions of genomes. Gene-nutrient interactions Relationships between nutritional status and genotype and their impact on human physiology and health, e.g. certain nu- trients may affect carcinogenesis but only in indi- viduals with a genetic predisposition to cancer or a certain genetic polymorphism may impact on car- 187 Gene probes Gene transfer cinogenesis, but only in individuals having a particular nutritional status. Also describes the molecular effects of nutrients on DNA and gene expression. Gene probes Molecules that have been labelled with radioactive isotopes, fluorescent dyes or enzymes that bind selectively to specific genes, thus allowing iden- tification or isolation. Also know as oligonucleotide probes. General Agreement on Trade and Tariffs The General Agreement on Trade and Tariffs (GATT) was a treaty and international trade organization in exis- tence from 1948 to 1995. GATT members worked to minimize tariffs, quotas, preferential trade agreements between countries, and other barriers to international trade. In 1995, GATT's functions were taken over by the World Trade Organization (WTO), an interna- tional body that administers trade laws and provides a forum for settling trade disputes among nations. GATT members sponsored eight specially organized rounds of trade negotiations. The last round of negotiations, called the Uruguay Round, began in 1986 and ended in 1994. At the end of the negotiations, the members of GATT, as well as representatives from seven other na- tions, signed a trade pact that will eventually cut tariffs overall by about one-third and reduce or eliminate other obstacles to trade. The pact also took steps to- ward opening trade in investments and services among member nations and strengthening protection for intel- lectual property. Throughout 1995, GATT and the WTO coexisted while GATT members sought their governments' approval for WTO membership. After the transition period, GATT ceased to exist. All of the 128 nations that were contracting parties to the 1994 GATT agreement eventually transferred membership to the WTO. Genes Units of inheritance that occupy specific loci within nucleic acid molecules (e.g. chromosomes, plasmids). Consist of specific DNA sequences that code for functional polypeptides or RNA molecules (e.g. rRNA, tRNA). Eukaryotic genes often consist of coding units (exons) separated by one or more non- coding unit (introns). Gene silencing Various genetic techniques used to suppress gene expression. Includes antisense technology and RNA interference technology. May also be induced by viral infection. Genetically engineered foods Foods that have been modified or that have been prepared with agents, e.g. enzymes, or contain ingredients that have been modified using genetic techniques. Used to confer new properties such as enhanced nutritional values and prolonged shelf life. More commonly referred to as genetically modified foods or GM foods. Genetically modified foods Commonly abbreviated to GM foods, but also referred to as genetically en- gineered foods. Foods and beverages that have been genetically modified or that have been prepared with agents (e.g. enzymes) or ingredients that have been modified using genetic techniques. Used to confer new properties such as resistance to herbicides or pests , enhanced nutritional values or extended shelf life. Regulations governing the cultivation and labelling of GM foods and feeds still varies widely between individual countries. Consumer accept- ability of these products is also highly variable. Genetically modified microorganisms Microor- ganisms that have been modified by genetic tech- niques to enhance their properties or confer upon them new properties. Abbreviated to GM microorgan- isms. Genetically modified organisms Organisms that have been modified by genetic techniques to en- hance their properties or confer upon them new proper- ties. Abbreviated to GM organisms or GMO. Genetic disorders Deleterious effects caused by alterations in the genetic material of organisms that may or may not be inherited in a Mendelian fashion. Genetic engineering General term covering various genetic techniques for in vitro manipulation of ge- netic material. Can be used for construction of new genes or novel combinations of genes, usually for in- sertion into host cells, placing genes under the control of different regulatory systems or introducing specific mutations into DNA molecules. Genetic fingerprinting Process by which different DNA samples are compared to determine if they are from the same individual, strain or species. Usually uses PCR to compare the characteristic polymorphic patterns of highly variable regions of genomic DNA, although a combination of RFLP and Southern blot- ting may also be used. Also known as DNA finger- printing. Genetic mapping Process by which the relative posi- tions of genes on DNA molecules (usually chromo- somes) and the distances between them are deter- mined. Genetics The study of heredity and variation, i.e. the patterns of inheritance of specific traits. Genetic techniques Methods used in the study of genetics and for the manipulation of genetic material. Genetic variants Organisms and cells that differ in phenotype due to differences in genotype , rather than to environmental factors. Gene transfer General term for insertion of foreign genes into cells or organisms. 188 Geniposide Germination Geniposide Iridoid glucoside which is found in the fruits of Gardenia jasminoides and is a constituent of gardenia yellow, a natural colorant used in a range of foods. Can be transformed into a blue pigment, which is also of potential use as a food colorant, by enzymic hydrolysis to genipin and reaction with amino acids. Genistein Yellow isoflavone which occurs in free or glucosidic form and has a weak oestrogenic effect. Found in soybeans, chick peas, lucerne and clo- ver. Genomes The genetic material of an organism or cell, comprising the complete set of genes. Genomics The study of genomes. Genotoxicity Quality or degree of being capable of exerting a damaging effect on the DNA that forms genes. Genotype The genetic constitution of an organism or cell that determines the expression of specific traits. Genotyping Genetic techniques (e.g. repetitive DNA sequence analysis, RAPD, gene sequence analy- sis, PCR, PFGE and RFLP) used to determine and compare the genetic constitution of organisms and cells. May be used in strain identification of mi- croorganisms to determine pathogenicity or to trace the source of outbreaks. Gentamicin One of the aminoglycoside antibiotics used to treat a range of bacterial infections in farm animals. Used especially in swine for treatment of colibacillosis and swine dysentry; also used for treat- ment of mastitis in cattle. Depletes relatively slowly from tissues, particularly kidneys. Relatively long withdrawal periods are required for animals intended for consumption. Gentians Plants of the genus Gentiana. Bitter compounds extracted from rhizomes and roots of these species are used in beverages, foods and medi- cines. Gentiobiose Disaccharide reducing sugar produced by reaction of two molecules of glucose in the pres- ence of ȕ -glucosidases. Systematic name is 6-O- ȕ - D -glucopyranosyl- D -glucose. Geobacillus Genus of rod shaped, aerobic, thermo- philic Gram positive bacteria of the family Bacil- laceae. Widely distributed in nature. Species produce a range of thermostable enzymes. For example, Geo- bacillus stearothermophilus produces arabinose isomerases and xylan degrading enzymes, G. thermoleovorans produces pullulanases, esterases and lipases, G. thermodenitrificans produces Į- amylases, G. caldoxylolyticus produces Į-N- arabinofuranosidases and G. pallidus produces xylan 1,4-ȕ-xylosidases. Geographical origin The specific geographical loca- tion (e.g. town, region, country) from which foods or beverages originate. Can be used to establish the au- thenticity and quality of a product. Certain foods and beverages can only be produced in a defined geo- graphical area, and labelling schemes and regulations have been implemented to indicate their authenticity, such as the Protected Designation of Origin scheme and other geographical indications established in EU legislation. Geosmin Heterocyclic volatile compound which natu- rally occurs in fresh water and imparts musty and earthy flavour and aroma taints to beverages such as drinking water and wines, as well as to freshwater fish. Geotrichum Genus of fungi of the family Dipodasca- ceae. Occur in soil, water, dairy products and grains. Species may be involved in the production of fermented foods, or may cause food spoilage. Geotrichum candidum imparts flavour and aroma to many types of cheese , and plays an important role in ripening of soft cheese; it also assists in the fer- mentation of cocoa. However, it can also cause spoilage of cream and butter, sour rot of citrus fruits, peaches and tomatoes, and watery soft rot of vegetables. G. citri-aurantii also causes sour rot of citrus fruits. G. klebahnii produces polygalactu- ronases with pectin-releasing activity. Geranial Structural trans isomer of citral derived from oxidation of geraniol and present in lemon- grass oils. Geraniol Colourless or pale yellow unsaturated monoterpene alcohol which has a rose-like aroma and occurs in geranium and rose essential oils. Used in flavourings. Geranyl acetate Volatile compound occurring as one of the natural flavour compounds in the essential oils of many herbs and spices. Extracted as a col- ourless liquid by fractional distillation of selected es- sential oils or prepared by acetylation of geraniol. Used in flavourings for foods and beverages. Germ Germinating portion or embryo of a cereal grain which is extracted and discarded when the grain is milled to make white flour. High in fats and several vitamins. Germicides Antimicrobial chemical agents used for disinfection, antisepsis or sterilization. Germination Sprouting of a seed, spore or other re- productive body. Influenced by a number of factors, including temperature, light and oxygen supply. Used commercially in preparation of cereals for manufac- ture of alcoholic beverages, and in production of mushrooms . 189 Germination capacity Ginsenosides Germination capacity Ability of a seed to germi- nate. Gesatop Alternative term for the herbicide simazine. Gestagens Steroid hormones which induce proges- tational effects in the uterus. Ghee Product made from butter; originally produced in India but now more widespread. Butter is melted at a high temperature, during which moisture is evapo- rated. Proteins are then removed from the melted but- ter by centrifugation. Gherkins West Indian gherkins are fruits produced by Cucumis anguria. Usually 4-5 cm long, and used mainly in pickles. In Europe, the term gherkins usu- ally refers to small ridge cucumbers. Ghrelin A peptide hormone produced by cells lining the stomach which stimulates appetite. Plasma levels increase prior to a meal and decrease afterwards. Ghre- lin also encourages the secretion of growth hormone (somatotropin) from the anterior pituitary gland. Giardia Genus of flagellate protozoan parasites of the family Hexamitidae. Alternates between two dif- ferent forms: a hardy, dormant cyst that contaminates water and food; and an active, disease-causing form that emerges after the parasite has been ingested. Infec- tion can occur through ingestion of dormant cysts in contaminated food and water, or by the faecal-oral route (through poor hygiene practices). Cysts can survive for weeks to months in cold water, and can therefore be present in contaminated wells, well wa- ter and water systems; the cysts are resistant to con- ventional treatments such as chlorination and ozonation. Giardia lamblia, the causative agent of giardiasis in humans, attaches itself to the intestinal mucosa and feeds on mucous secretions. Giardiasis Disease caused by infection with Giardia lamblia. Commonly transmitted through ingestion of food or water contaminated with cysts. Characterized by watery diarrhoea, abdominal cramps, nausea and flatulence. Infection may be asymptomatic. Gibberellic acid Plant growth regulator belonging to the gibberellins group which may be obtained com- mercially by culture filtration of the fungus Gibberella fujikuroi. Gibberellins Any of a group of plant growth regu- lators originally produced by Gibberella fujikuroi. Promotes processes such as stem elongation, germi- nation and flowering. Often used to stimulate germi- nation of dormant grain such as barley during malting. Giblets Edible offal from the carcasses of poultry and game birds. Giblets include the livers, hearts, gizzards and necks of the birds; they are usually re- moved before the birds are cooked. Giblets, with the exception of livers, are often used to make gravy, stocks or soups. Gigartina Genus of seaweeds found on rocky shores around the world. Some species are used as a source of carrageenans and nutraceuticals in the food indus- try. Gin Spirits made by flavouring rectified ethanol with juniper and other plant ingredients, usually by re- distillation of the spirits with the flavourings. Gingelly oils Alternative term for sesame oils. Gingelly seeds Alternative term for sesame seeds. Ginger Rhizomes from Zingiber officinale. Used fresh or dried as spices in a number of foods and bever- ages, including gingerbread and ginger beer. Pungency is due to the presence of gingerols. May also refer to related Curcuma spp. such as C. xanthor- rhiza. Ginger ale Ginger-flavoured sweetened carbon- ated beverages, often added to spirits such as whisky or brandy prior to consumption. Ginger beer Effervescent ginger -flavoured bever- ages. Traditionally, these are slightly alcoholic and made by fermentation of a sugar medium contain- ing ginger and other flavourings. Industrial produc- tion often does not involve fermentation, and the resul- tant product is usually alcohol-free and marketed as a soft drink. Gingerbread Dark molasses-based cakes or bis- cuits flavoured with ground ginger and other spices. Often cut into shapes, decorated and glazed. Gingerols Phenolic ketones which are the major pungent principles of fresh ginger. Ginjoshu Type of sake. Ginkgo nuts Seeds produced by Ginkgo biloba (maidenhair tree), a plant grown in Asia. Fresh nuts are soaked in hot water to loosen the skin. Also avail- able dried and canned in brines. Used widely in Japa- nese cooking and in Chinese medicines. Ginseng Root of the plant Panax ginseng, used for preparation of ginseng beverages. Widely consid- ered to have health-promoting properties, possibly re- lated to the presence of saponins (ginsenosides). Ginseng beverages Beverages that contain gin- seng as a major ingredient. Considered by some to be health beverages. Ginseng saponins Alternative term for ginse- nosides. Ginsenosides Complex mixture of saponins which are believed to be the active components of ginseng, Panax ginseng, and are thought to be responsible for 190 Girdling Glucanases the reported health benefits associated with this plant. Also known as ginseng saponins. Girdling Removal of a strip of bark from the circum- ference of a tree, with the intention of improving growth or quality of fruits. Gizzards Muscular, thick-walled stomachs of birds, which lie between the proventriculus and the upper limit of the small intestine; poultry gizzards form a part of edible offal. In birds, the function of the gizzard is to grind food, typically with swallowed grit and small stones. Glass Brittle, usually transparent or translucent mate- rial used widely to make bottles and other contain- ers. Manufactured by fusing sand (silica and silicates) with soda and lime. Also refers to individual drinking vessels made from glass. Glass bottles Bottles made from glass which are commonly used as containers for beverages and other liquids. Available in a range of shapes, capacities and colour. Glass containers Containers made from glass which may be used to store or package a range of foods. Include glass bottles, beakers, jars and pots. Glassine Smooth, thin, glossy transparent or semi- transparent paper made primarily from chemical wood pulps. Has a high resistance to transmission of air and is grease resistant. To make it impervious to water vapour, some glassine is lacquered, laminated or waxed. Used for wrapping food. Glassiness Optical properties relating to the ex- tent to which a product appears to have the surface properties of glass, i.e. smoothness, uniformity, shini- ness and glossiness. Glass transition Reversible sudden transition of an amorphous polymer from a glassy condition to a flexi- ble condition when it is heated to a specific tempera- ture range (glass transition temp.). Due to a change in the arrangement of the polymer molecules from a coiled and motionless state to one where they are free to move. Glass transition temp. Temperature range at which the glass transition (change from a glassy to a flexible condition) of polymers takes place. Value var- ies according to the polymer and the range is relatively small. Glazes Substances, such as milk, beaten eggs or thin jams, which are used to create a shiny appearance or provide protective coatings on foods. Also, smooth, glossy, glass-like materials fused onto the surface of pottery, where they form hard, impervious decorative coatings. Glazing Application of a liquid, such as milk or beaten eggs, to hot or cold foods to produce a smooth, shiny coating after setting. For example, milk or beaten eggs can be brushed onto pastry before baking to add colour and shine. GLC Abbreviation for gas liquid chromatography. Gliadins Cereal proteins from the endosperm of wheat or rye. The elastic constituent of gluten. Gliocladium Genus of mitosporic filamentous fungi of the order Hypocreales and class Sordariomycetes. Occur in soil and decaying plant material. Causes pink rot of plants, including palms, particularly in winter. Telomorphs of Gliocladium include Nectria, Hypocrea and Nectriopsis. Certain Gliocladium spp. can be used to control various fungal diseases in food crops. Gliotoxin Mycotoxin produced by Trichoderma viride and species of Aspergillus, Gliocladium and Penicillium. Inhibits replication of certain viruses (e.g. polioviruses) and also exhibits antibacterial activity, antifungal activity and antitumour ac- tivity. Globe artichokes Common name for Cynara scoly- mus. Plant has a large, thistle-like flower head with edible fleshy leaves and heart. Generally eaten cooked, either hot or cold, and can be canned. Small, immature flower heads may also be consumed, cooked and pre- served in olive oils. Globe artichokes are high in fi- bre, low in fat and calories, and rich in vitamin A and vitamin C. Globins Animal proteins that contain some arginine and tryptophan, are rich in histidine and are deficient in isoleucine. They often form the protein portion of conjugated proteins, e.g. the globins in haemoglobin or myoglobin . Globulins Any of a class of spherical or globular shaped high molecular weight proteins which are relatively insoluble in water and soluble in dilute salt solutions. Found widely throughout nature; they in- clude lactoglobulins, serum globulins and immu- noglobulins. Subdivided into Į-, ȕ- and Ȗ-globulins. Ȗ-Globulins A fraction of globulins obtained follow- ing separation of plasma globulins by SDS-PAGE. Occur in animal tissues and products derived from them, and include immunoglobulins. Gloss Optical properties relating to the surface lustre or sheen on a product. Gloss is important to the attractiveness of specific products such as gelatin desserts and buttered vegetables. Glucagon Polypeptide hormone secreted by pancre- atic cells in response to a decrease in serum glucose. Acts by promoting the conversion of liver glycogen into glucose, thereby increasing the level of blood sugar, and has an opposite effect to that of insulin. Glucanases General term for enzymes that hydro- lyse glucans. Include glucan endo-1,3-ȕ- D - 191 ȕ-Glucanases Glucono-į-lactone glucosidases, endo-1,3(4)-ȕ-glucanases and licheninases. ȕ-Glucanases Alternative term for endo-1,3(4)-ȕ- glucanases. 1,4-Į-Glucan branching enzymes EC 2.4.1.18. Glycosyltransferases which transfer a segment of a 1,4-Į- D -glucan chain to a primary hydroxyl group in a similar glucan chain. Convert amyloses into amy- lopectins in plants and produce glycogen in bac- teria. Commonly referred to in plants as starch branching enzymes, and their activity is important for starch structure. Glucan endo-1,3-ȕ- D -glucosidases EC 3.2.1.39. Glycosidases which hydrolyse 1,3-ȕ- D -glucosidic linkages in 1,3-ȕ- D -glucans. Also known as laminari- nases. Important in the malting and brewing indus- tries, and potentially useful for production of func- tional oligosaccharides. May be involved in the ripening/softening of fruits and in plant defence. Glucan 1,4-Į-glucosidases EC 3.2.1.3. Also known as glucoamylases, these enzymes hydrolyse terminal 1,4-linked Į- D -glucose residues successively from non-reducing ends of chains, releasing ȕ- D - glucose. Can also hydrolyse Į- D -1,6-glucosidic link- ages, although at a slower rate. Useful for degradation of starch (saccharification) for production of sugar syrups and for conversion of residual dex- trins to fermentable sugars during production of low calorie beer. 4-Į-Glucanotransferases EC 2.4.1.25. Glycosyl- transferases which transfer a segment of a 1,4-Į- D - glucan to a new position in an acceptor, which may be glucose or another 1,4-Į- D -glucan. Involved in starch metabolism in plants. Applications include the synthesis of cycloamylose and modified starches, and, together with maltogenic amylases, these en- zymes may also be useful for the synthesis of isomal- tooligosaccharides, useful as low calorie sweet- eners and prebiotics. Also known as dispropor- tionating enzymes, dextrin glycosyltransferases, amy- lomaltases and D-enzymes. Glucans Soluble, indigestible polysaccharides composed predominantly of D -glucose residues and found in cereals such as oats, barley and rye. ȕ-Glucans Polysaccharides composed of D - glucose in either straight or branched chains with ȕ- glycosidic linkages. Present in the bran of most cere- als, particularly barley and oats, and in yeasts and mushrooms. Certain ȕ-glucans exhibit potentially beneficial biological activities and are used as sources of soluble fibre in dietary supplements and functional foods. Glucides Subclass of saccharides. Glucitol Alternative term for sorbitol. Glucoamylases Alternative term for glucan 1,4-Į- glucosidases. Glucobrassicin Alternative term for 3-indolylmethyl glucosinolate, one of the major glucosinolates found in vegetables of the genera Brassica and Raphanus. Glucocorticoids Any of a group of corticosteroids secreted by the adrenal cortex that controls carbohy- drate and protein metabolism by promoting glycogen deposition in the liver. Glucocorticoids have anti- inflammatory activity. Glucokinases EC 2.7.1.2. Kinases which, along with hexokinases, catalyse the transfer of a phos- phate group from ATP to D -glucose to form D - glucose 6-phosphate, the first reaction of glycolysis. Often measured to assess metabolism of carbohy- drates. Also used as an alternative name for hexokinases (EC 2.7.1.1). Glucomannans Viscous polysaccharides com- prising glucose and mannose which occur naturally in the food reserves of some plants, such as konjac (elephant yams). Like galactomannans they form thermally reversible gels with xanthan. Gluconacetobacter Genus of acetic acid bacteria of the family Acetobacteraceae, containing species previously included in the genus Acetobacter. Found in a wide variety of fruits and fruit nectars, where they can cause spoilage. Some species (e.g. Glu- conacetobacter europaeus) are used in the manufac- ture of vinegar. Gluconates Salts of gluconic acid. Used as acidu- lants or chelating agents in foods, beverages, food supplements, pharmaceuticals, etc. Also used as carriers for minerals in food fortification. Ob- tained by the fermentation of glucose. Gluconic acid Organic acid which is soluble in water and alcohol and is formed by oxidation of glucose in which the CHO group has been converted to COOH. Predominant acid found in honeys. Gluconobacter Genus of Gram negative, aerobic, rod-shaped acetic acid bacteria of the family Ace- tobacteraceae. Occur in soil, plants, fruits, cider, beer, wines and flowers. Species are used in the pro- duction of vinegar, and may cause spoilage of beer. An important industrial microbial strain. Frequently used in biotechnological applications such as biocon- versions, biotransformations and technology in- volving biosensors. Most of these processes make use of membrane-bound polyol dehydrogenases and dextran dextrinases. Glucono-į-lactone Lactone that forms gluconic acid when dissolved in water. Used as an acidulant 192 Glucooligosaccharides Glucosides and hence to induce gelation in a range of foods, and as a leavening agent in bakery products. Also fre- quently used as an additive in cheese, meat and sausages. Glucooligosaccharides Oligosaccharides with a range of structures based on glucose. Many are partly or totally resistant to digestive enzymes in the human gastrointestinal tract, but can be fermented by colonic microflora to produce short chain fatty acids. Used as dietary prebiotics either alone or in conjunction with probiotic bacteria to regulate gas- trointestinal transit, improve the composition of the colonic microflora and provide various other health benefits, such as reduced risk of colorectal cancer. Dextransucrases from bacteria such as Leu- conostoc mesenteroides can be used to prepare glu- cooligosaccharides. Glucoraphanin One of the naturally occurring glu- cosinolates found in Cruciferae, e.g. broccoli, cabbages and cauliflowers. Metabolized to sul- foraphane which has been attributed with antim- icrobial activity and anticarcinogenicity. Young sprouts of broccoli and cauliflowers are particularly rich in glucoraphanin. Also called sulforaphane glu- cosinolate. Glucosamine Crystalline amino derivative of glu- cose and the principal component of chitin, muco- proteins and mucopolysaccharides. Glucose Monosaccharide with six carbon atoms. Free glucose is present naturally in fruits and honeys and it is the monomer unit from which starch and cellu- loses are synthesized; commercial manufacture of glucose is by hydrolysis of starch. It is the main energy source for living cells. Glucose is a constituent of su- crose and is used in sweeteners. Free glucose has 0.7-0.8 times the sweetness of sucrose. The D - stereoisomer of glucose is known as dextrose. Glucose isomerases EC entry for these enzymes has been deleted. Activity now attributed to xylose isomerases (EC 5.3.1.5) or, in the presence of arse- nate, to glucose-6-phosphate isomerases (EC 5.3.1.9). The term glucose isomerases is still used widely, how- ever. Catalyse the isomerization of glucose to fructose and used for large scale production of fruc- tose high corn syrups and dextrins for use in a variety of foods and beverages. Glucose oxidases EC 1.1.3.4. Flavoenzymes that oxidize ȕ- D -glucose to ȕ- D -gluconic acid and H 2 O 2 . Used for stabilizing foods and beverages by removing glucose and O 2 , and preventing deterioration of col- our and flavour (e.g. liquid egg whites, fruit juices, beer, wines, mayonnaise, bread dough and cheese). Also used in biosensors for determi- nation of glucose levels and for removal of O 2 in food packaging, thus protecting against oxidative deterio- ration. Glucose-6-phosphate Primary metabolite of glu- cose in living cells. Formation of glucose-6- phosphate from glucose is the first reaction in glyco- lysis and is catalysed by hexokinases. Glucose-1-phosphate adenylyltransferases EC 2.7.7.27. Also known as ADP-glucose pyrophosphory- lases, these enzymes transfer a phosphate group from ATP to Į- D -glucose 1-phosphate to form pyrophos- phate and ADP-glucose. They are key enzymes in the starch biosynthetic pathway in plants. Glucose syrups Syrups consisting predominantly of glucose. Produced commercially by hydrolysis of starch; corn starch is the most commonly used substrate. Included in a variety of foods to adjust fla- vour, colour, texture and stability. Glucose tolerance Ability of the body to metabolize glucose in the bloodstream. Impaired glucose toler- ance is a pre-diabetic state of dysglycaemia that is as- sociated with insulin resistance, the metabolic syndrome and increased risk of cardiovascular diseases. Glucose tolerance tests are one of the tools used to diagnose diabetes. Glucosidases General term for glycosidases which act on glucose residues specifically. Histori- cally, a more general term for glycosidases. Į-Glucosidases EC 3.2.1.20. Glycosidases which hydrolyse terminal, non-reducing 1,4-linked Į- D - glucose residues of oligosaccharides and Į- D - glucosides. Polysaccharides are hydrolysed rela- tively slowly. Hydrolyse carbohydrates including maltose, sucrose and starch and catalyse a variety of transglycosylation reactions, e.g. for the synthe- sis of prebiotics. Į-Glucosidase inhibitors in foods may be useful in controlling postprandial hypergly- caemia for type 2 diabetes management. Also known as maltases and glucoinvertases. ȕ-Glucosidases EC 3.2.1.21. Glycosidases which hydrolyse terminal non-reducing ȕ- D -glucose residues with the release of ȕ- D -glucose. Substrates include cellobiose, cellooligosaccharides and aryl-ȕ- glucosides. These enzymes have a number of uses in the food industry, including debittering of table olives, increasing the aroma of wines, enrichment of genistein in soy protein concentrates and re- lease of phenols from phenolic glycosides in plant tissues. Glucosides A range of glycosides found mainly in plants, the sugar component of which is glucose. These compounds may be useful as aroma precursors, pigments and surfactants, and may exhibit anti- oxidative activity. However, cyanogenic glucosides [...]... encapsulating agents for flavourings; medium viscosity gums, e .g gum tragacanth and alginates, provide body and are useful emulsifying agents, e .g in salad dressings; and high viscosity gums, e .g guar gums and locust bean gums, are good thickeners and stabilizers and improve mouthfeel in reduced fat or low fat foods Gel forming gums, e .g carrageenan and gellan gums, are employed as gelling agents to produce... compliance Gooseberries Green, yellow or red fruits produced by Ribes grossularia or R uva-crispa Consumed fresh or cooked Also used in jams, jellies, juices, syrups and as the base of flavourings Goose eggs Eggs produced by geese Consist of approximately 13.9% proteins and 13.3% fats, and weigh approximately 144 g Have a high cholesterol content (more than 1200 mg/egg) and larger egg yolks than eggs produced... sucking insects on fruit trees Classified by WHO as unlikely to present acute hazard in normal use Goat milk GM foods Abbreviation for genetically modified foods GM microorganisms Abbreviation for genetically modified microorganisms GMO Abbreviation for genetically modified organisms GM organisms Abbreviation for genetically modified organisms GMP Abbreviation for guanosine monophosphate Gnathostoma Genus... referred to as transglucosylases Glucuronic acid Uronic acid derived by oxidation of the carbon-6 atom to a carboxyl group Potential toxins are conjugated with glucuronic acid in the liver to form glucuronides before being excreted Glucuronic acid is also found in mucopolysaccharides -Glucuronidases EC 3.2.1.139 Glycosidases which hydrolyse -1 ,2-glycosidic bonds of the 4-Omethyl-D-glucuronic acid side... emulsification, thickening and coating of foods and beverages Gum guaiac Alcohol soluble gums obtained as a resin from Guajacum officinale or G sanctum wood Predominantly composed of - and -guaiaconic acids with guaiacic acid and vanillin Primarily used as antioxidants Gum kondagogu Exudates of Cochlospermum gossypium, a tree native to India Classified as a variety of karaya gums, although the gums do differ... neurotoxin -N-oxalyl- , diaminopropionic acid in grass peas Glutamates Salts of glutamic acid used as flavourings, e .g the flavour enhancer monosodium glutamate Glutamic acid Amino acid which is believed to play a part in the high-quality flavour of young fresh vegetables and in the enhancement of other flavours in general Salts of glutamic acid (glutamates) are widely used as flavourings Glutaminases... richness of goose eggs means they are particularly well suited to use in desserts Goose livers Livers from geese; part of edible offal May be cooked using a variety of techniques including sauteing, grilling and frying Also used to make pates or mousses In France, the livers of geese that have undergone fattening by gavage are used to prepare foie gras This has a richer flavour than that produced using duck... brown sugar and nuts Granulated sugar Crystalline solid comprising at least 99.8% sucrose Granulated sugar is produced by crystallization or graining of concentrated sugar Granulation 199 syrups and is the most pure form of sugar manufactured from sugar beets and sugar cane Granulation Processing of a food into small compact particles (granules) Granulators are often used in cane and beet sugar manufacture... as cluster beans Guar gums 202 Guar gums High viscosity gums isolated from ground endosperms of the legume Cyamopsis tetragonoloba, also known as guar beans or cluster beans Composed of repeating (1 4 )- -Dmannopyranosyl units with branches of -Dgalactopyranosyl units linked via (1 6) linkages Mannose:galactose ratio is 2:1 These gums are used as thickeners (thickening capacity is approximately 8fold... foams and flavourings Synonym for gum arabic Gum arabic Synonym for gum acacia Gum balls Alternative term for chewing gums Gum confectionery Collective terms for chewing gums and bubble gums and their products Gurdani Gum ghatti Moderate viscosity gums obtained as stem exudates from Anogeissus latifolia Major components are arabinose, galactose, mannose, xylose and glucuronic acid in a ratio of 10:6:2:1:2 . hydro- lyse glucans. Include glucan endo-1, 3- - D - 191 ȕ-Glucanases Glucono-į-lactone glucosidases, endo-1,3(4 )- -glucanases and licheninases. ȕ-Glucanases. hydrolyse terminal, non-reducing - D -galactose residues in - D -galactosides, including galactose oligosaccharides, galactomannans and galac- tolipids. Can