Tài liệu Tự điển Food Science, Technology And Nutrition - Vần G docx

gastric inhibitory peptide Peptide hormone secreted by themucosa of the duodenum and jejunum in response to absorbed fat and carbohydrate; stimulates the pancreas to 207... secrete insul

fungi Subdivision of Thallophyta, plants without differentiationinto root, stem and leaf; cannot photosynthesise, all are parasites

or saprophytes Microfungi are moulds, as opposed to largerfungi, which are mushrooms and toadstools yeasts are some-times classed with fungi Mycorrhizal fungi form symbiotic asso-ciations with tree roots

Species of moulds such as Penicillium, Aspergillus, etc are

important causes of food spoilage in the presence of oxygen andrelatively high humidity Those that produce toxins (mycotoxins)are especially problematical

On the other hand, species of Penicillium such as P cambertii and P rocquefortii are desirable and essential in the ripening of

some types of cheese

A number of larger fungi (mushrooms) are cultivated, andother wild species are harvested for their delicate flavour The

mycelium of smaller fungi (including Graphium, Fusarium and Rhizopus spp.) are grown commercially on waste carbohydrate

as a rich source of protein (mycoprotein) for food manufacture

furans Derivatives of five-membered heterocyclic compounds(C4H4O), associated with caramel-like, sweet, fruity, nutty andmeaty flavours in foods; formed in foods by the maillard reac-tion and thermal degradation of carbohydrates

furcellaran Danish agar; an anionic, sulphated polysaccharide

extracted from the red alga, Furcellaria fastigiata, structurally

similar to carrageenan; used as a gelling agent

fusel oil Alcoholic fermentation produces about 95% alcohol and5% fusel oil, a mixture of organic acids, higher alcohols (propyl,butyl and amyl), aldehydes and esters, known collectively as con-geners Present in low concentration in wines and beer, and highconcentration in pot-still spirit On maturation of the liquor fuseloil changes and imparts the special flavour to the spirit Many

of the symptoms of hangover can be attributed to fusel oil inalcoholic beverages

fussol Monofluoroacetamide, a systemic insecticide for treatingfruit

F value The time required to destroy a given percentage of organisms at a specified reference temperature and Zvalue

micro-G

gaffelbitar Semi-preserved herring in which microbial growth ischecked by the addition of 10–12% salt and sometimes benzoicacid

galactans polysaccharides composed of galactose derivatives;

a major constituent of carageenan

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galacticol See dulcitol.

Galactomin TM A preparation free from lactose and galactose, forpeople suffering from lactose intolerance

galacto-oligosaccharides Small oligosaccharides consisting ofglucosyl-(galactose)2–5, formed from lactose by galactosyl transfer catalysed by lactase (EC 3.2.1.23) Considered to be aprebiotic

galactorrhoea Abnormal secretion of milk, due to excessivesecretion of prolactin

galactosaemia Congenital lack of UDP-glucose ferase (EC 2.7.7.12), or more rarely galactokinase (EC 2.7.1.6)leading to elevated blood concentration of galactose, and hencenon-enzymic glycation of proteins, and the development ofcataract and neurological damage; subjects suffer mental retar-dation, growth failure, vomiting and jaundice, with enlargement

galactosyltrans-of liver and spleen Treatment is by severe restriction galactosyltrans-of lactoseintake, since this is the only significant source of galactose

galactose A six-carbon monosaccharide (hexose), differing fromglucose in orientation of the hydroxyl group on carbon-4.About one-third as sweet as sucrose The main dietary source isthe disaccharide lactose in milk, important in formation of thegalactolipids (cerebrosides) of nerve tissue

See also carbohydrates; galactosaemia.

b-galactosidase Enzyme (EC 3.2.1.23) that hydrolyses β-galactans

in non-starch polysaccharides; responsible for loss of firmnessduring ripening and storage of fruits

galangal Root spices (Alpinia galanga, A officinarum) related to

ginger, but with a faint flavour of camphor

GalanolTM borage seed oil, a rich source of γ-linolenic acid, as

a dietary supplement

galenicals Crude drugs; infusions, decoctions and tinctures pared from medicinal plants

pre-gallates Salts and esters of gallic acid, found in many plants Used

in making dyes and inks, and medicinally as an astringent Propyl,octyl and dodecyl gallates are legally permitted antioxidants infoods (E-310–312)

gall bladder The gland in the liver that stores the bile beforesecretion into the small intestine

See also gallstones; gastrointestinal tract.

gallon A unit of volume The Imperial gallon is 4.546 litres,and the US (or Queen Anne) gallon is 3.7853 litres; therefore 1Imperial gallon = 1.2 US gallons

gallstones (cholelithiasis) Crystals of cholesterol, bile salts andcalcium salts, formed in the bile duct of the gall bladder whenthe bile becomes supersaturated

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game Non-domesticated (i.e wild) animals and birds shot forsport and eaten rabbit and pigeon may be shot at any time, butother game species, such as grouse, hare, partridge, pheasant,quail, deer (venison) and wild duck, may not be shot during theclosed season, to protect breeding stocks Game birds are gen-erally raised on farms to provide sport, rather than being hunted

in the wild, and increasingly game species are farmed and killed

in conventional ways to provide food Traditionally, game is hungfor several days to soften the meat, when it develops a strongflavour

gammelost Norwegian dark brown cheese with mould growth onthe rind that is pressed into the paste while it is ripening

gammon See bacon.

gangliosides Glycolipids, structurally similar to cerebrosides, butwith a charged polar oligosaccharide head region

garam masala A mixture of aromatic spices widely used in Indiancooking; contains powdered black pepper, cumin, cinnamon,cloves, mace, cardamom seeds and sometimes also corianderand/or bay leaf

garbanzo See chickpea.

garbellers 15th century; people appointed by the Grocers’Company of London to inspect spices and other groceries, anddestroy adulterated products

gari Fermented cassava meal Cassava is grated, soaked in waterand left to undergo bacterial fermentation for 2–5 days in per-meable sacks so that liquid drains out; the resulting solid mass issieved and lightly toasted or fried (garified)

garlic The bulb of Allium sativum with a pungent odour when

crushed, widely used to flavour foods There is some evidencethat garlic has a beneficial effect in lowering blood cholesterol.Composition/100 g: (edible portion 87%) water 58.6 g, 624 kJ(149 kcal), protein 6.4 g, fat 0.5 g, carbohydrate 33.1 g (1 g sugars),fibre 2.1 g, ash 1.5 g, Ca 181 mg, Fe 1.7 mg, Mg 25 mg, P 153 mg, K

401 mg, Na 17 mg, Zn 1.2 mg, Cu 0.3 mg, Mn 1.7 mg, Se 14.2µg,

26µg carotenoids, vitamin K 1.4mg, B10.2 mg, B20.11 mg, niacin0.7 mg, B61.24 mg, folate 3µg, pantothenate 0.6mg, C 31mg

garlic mustard A common wild plant of hedgerows and woodland

(Alliaria petiolata); the leaves have a garlic-like flavour and can

be used in salads or cooked as a vegetable

gas storage, controlled (modified) See packaging, modified

atmosphere

gastrectomy Surgical removal of part or all of the stomach

gastric inhibitory peptide Peptide hormone secreted by themucosa of the duodenum and jejunum in response to absorbed fat and carbohydrate; stimulates the pancreas to

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secrete insulin.Also known as glucose-dependent insulinotropicpolypeptide.

gastric secretion Gastric juice contains the enzymes chymosin(EC 3.4.23.4), lipase (EC 3.1.1.3), pepsinogen (the inactive pre-cursor of pepsin, EC 3.4.23.1), intrinsic factor, mucin andhydrochloric acid

The acid is secreted by the parietal (oxyntic) cells at a strength

of 0.16 mol/L (0.5–0.6% acid); the same cells also secrete sic factor, and failure of acid secretion (achlorhydria) is asso-ciated with pernicious anaemia due to failure of vitamin b12

gastric ulcer See ulcer.

gastrin Peptide hormone secreted by G-cells of the antrum of thestomach; stimulates parietal cells to secrete acid

gastroenteritis Inflammation of the mucosal lining of the stomach(gastritis) and/or small or large intestine, normally resulting from infection, or, in the case of gastritis, from excessive alcoholconsumption

gastroenterology The study and treatment of diseases of the trointestinal tract

gas-gastrointestinal tract (see p 209) A term for the whole of the

digestive tract, from the mouth to the anus Average length 4.5 m (15 feet)

gastrolith Stone in the stomach, usually builds up around abezoar

gastroplasty Surgical alteration of the shape of the stomachwithout removing any part Has been used to reduce the physi-cal capacity of the stomach as a treatment for severe obesity

gastrostomy feeding Feeding a liquid diet directly into thestomach through a tube that has been surgically introducedthrough the abdominal wall

See also enteral nutrition; nasogastric tube.

Gatorade TM A sports drink containing mineral salts in mately the proportions they are lost in sweat

approxi-gavage The process of feeding liquids by stomach tube Alsofeeding an excessive amount (hyperalimentation)

GC-MS Gas chromatography linked to a mass spectrometer asthe detection system

gean Scottish name for the fruit of Prunus avium; also known as

wild cherry, sweet cherry and mazzard

gefillte fish (gefilte, gefültte) German for stuffed fish; of Russian

or Polish origin, where it is commonly referred to as Jewish fish.208

The whole fish is served and the filleted portion chopped andstuffed back between the skin and the backbone More fre-quently today, the fish is simply chopped and made into balls,which are either fried or boiled In the UK has been referred tolegally as ‘fish cutlets in fish sauce’ instead of a fish cake.

gel Colloidal suspension (see colloid) consisting of a continuous

phase (commonly water) and a dispersed phase (the gellingagent); the water molecules are held in a three-dimensionalnetwork of the gelling agent Examples include plant gums, gela-tine, pectin

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GASTROINTESTINAL TRACT

gelatine A soluble protein prepared from collagen or bones byboiling Type A is prepared by acid treatment of collagen and has

an isoionic point of 7–9 Type B is prepared by alkaline treatmentand has an isoionic point of 4.8–5.2 because of loss of the amidegroups of glutamine and asparagine Used for sugar confec-tionery, in canned meats, for table jellies and in pharmaceuticalcapsules Gelatine from fish (especially the swim bladder) is isinglass Gelatine has an unusual amino acid composition:14% hydroxyproline, 16% proline and 26% glycine; of poornutritional value, since it lacks tryptophan Chinese gelatine is agar

gelatine sugar Obsolete name for glycine

gelatinisation Formation of a water-retentive gel by expansion ofstarch granules when heated in moist conditions

See also staling.

gelation The formation of the pectin gel that gives fruit preservesand jams their texture; dependent on the pectin, sugar, acid andwater content of the fruit

gellan gum A polysaccharide produced by fermentation of the

bacterium Sphingomonas elodea (Pseudomonas elodea), used in

some foods

gelograph Instrument for measuring the viscosity or gel strength

of a protein (or other) solution using an oscillating needle

gelometer See bloom gelometer.

gemfibrizol See fibric acids.

generic descriptor The name used to cover the different cal forms of a vitamin that have the same biological activity

chemi-genetic diseases Also known as inborn errors of metabolism eases due to a single defective gene, with a characteristic pattern

Dis-of inheritance in families Many affect the ability to metaboliseindividual amino acids or carbohydrates and can be treated bydietary restriction

See also amino acid disorders; disaccharide intolerance.

genetic modification A change in the genes of a living organism,

as occurs in nature, and which has been used for many years inselective breeding, or, more quickly and specifically, in the labo-ratory, when genes from another organism may be introduced(sometimes known as genetic engineering)

See also gm foods; substantial equivalence.

genome The complete genetic sequence of an organism, hencethe science of genomics

genomics, nutritional General term to include both ics and nutrigenomics

nutrigenet-gentiobiose A disaccharide consisting of two molecules ofglucose joined β-1,6

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Gentleman’s relishTM A paste of anchovies, butter, cereal, salt andspices developed in the UK in the 19th century; also called patumpeperium.

geophagia Eating of dirt or soil

See also pica.

geosmin Dimethyl-bicyclodecanol; microbial metabolite that cancause earthy or musty off-flavour in fish and drinking water

GEP Gas exchange preservation, see packaging, modified

atmosphere

Gerber test For fat (cream) in milk The milk is mixed with phuric acid (or detergent) and amyl alcohol; the protein and car-bohydrate are dissolved, and the fat separates out The reaction

sul-is carried out in a Gerber bottle with a thin graduated neck, inwhich the fat collects for measurement after centrifugation

germ, wheat The embryo or sprouting portion of the wheat berry,comprising about 2.5% of the seed Contains 64% of the vitamin

B1, 26% of the vitamin B2, 21% of the vitamin B6and most ofthe fat of the grain It is discarded, with the bran, when the grain

is milled to white flour

Wheat germ oil is 20% saturated, 16% mono-unsaturated,65% polyunsaturated, contains 149 mg vitamin E, 25 mg vitaminK/100 g

See also flour, extraction rate.

geuse (gueuze) See beer.

GFP See green fluorescent protein.

ghatti gum Or Indian gum, polysaccharide exudate of the tree

Anogeissus latifolia The gum is formed as a protective sealant

when the bark Used in the same way as gum arabic

ghee (or ghrt) Clarified butter fat; may also be made from etable oils

veg-Composition/100 g: water 0.2 g, 3667 kJ (876 kcal), protein 0.3 g, fat 99.5 g (of which 66% saturated, 30% mono-unsaturated,4% polyunsaturated), cholesterol 256 mg, carbohydrate 0 g, Ca

4 mg, P 3 mg, K 5 mg, Na 2 mg, vitamin A 840µg RE (824µgretinol, 193µg carotenoids), E 2.8mg, K 8.6mg

gherkin Young green cucumber of a small variety (Cucumis anguira), used mainly for pickling.

ghrelin A peptide hormone secreted by cells in the nal tract that both stimulates the secretion of growth hormoneand regulates feeding behaviour and energy balance by acting onthe hypothalamus Secretion is increased in the fasting state andunder conditions of negative energy balance, and decreasedunder conditions of positive energy balance Secretion isincreased in anorexia and is low in the fasting state in obesepeople

gastrointesti-211

ghrt See ghee.

giardiasis Intestinal inflammation and diarrhoea caused by

infection with the protozoan parasite Giardia lamblia.

gibberellins Plant growth substances derived from gibberellic

acid, originally found in the fungus Gibberella fujikori growing

on rice About 30 gibberellins are known; they cause stem sion and allow mutant dwarf forms of plants to revert to normalsize, induce flower formation and break bud dormancy Used inhorticulture to control flowering and fruit maturation, also toinduce α-amylase in malting (see malt) of barley.

exten-giblets The edible part of the entrails of a bird; gizzard, liver, heartand neck

gigot French; leg of lamb or mutton In Ireland gigot chops areneck chops used for stewing

gill Obsolete British measure of liquid, 5 or 10 fl oz (1/4or 1/2pint),varying regionally

gin Alcoholic drink made by distilling fermented starch or othercarbohydrate, flavoured mainly with juniper berries togetherwith coriander seeds, angelica, cinnamon, orange and lemon peel.Distillate is diluted to 40% alcohol by volume, 925 kJ (220 kcal)/

100 mL Name derived from French genièvre (juniper); originally

known as geneva, schiedam or hollands, since it is Dutch inorigin

There are two types of English gin: Plymouth gin with a fullerflavour, and London gin Plymouth gin has a protected designa-tion and legally may only be distilled in Plymouth; it is made byadding the botanicals to the still, while for London gin they areadded to the distilled liquor

Dutch and German gins are more strongly flavoured thanEnglish or American; steinhäger and schinkenhäger are distilledfrom a mash of wheat, barley and juniper berries; wacholder ismade from neutral spirit flavoured with juniper Dutch gin may

be jonge (young) or oude (aged, matured).

gingelly (gingili) See sesame.

ginger The rhizome of Zingiber officinale, used as a spice

Pre-served ginger is made from young fleshy rhizomes boiled withsugar and either packed in syrup or crystallised

Fresh ginger, composition/100 g: (edible portion 93%) water78.9 g, 335 kJ (80 kcal), protein 1.8 g, fat 0.8 g, carbohydrate 17.8 g(1.7 g sugars), fibre 2 g, ash 0.8 g, Ca 16 mg, Fe 0.6 mg, Mg 43 mg,

P 34 mg, K 415 mg, Na 13 mg, Zn 0.3 mg, Cu 0.2 mg, Mn 0.2 mg, Se0.7µg, E 0.3mg, K 0.1mg, B10.03 mg, B20.03 mg, niacin 0.8 mg,

B60.16 mg, folate 11µg, pantothenate 0.2mg, C 5mg

ginger beer Alcoholic beverage made by fermenting a sugar tion flavoured with ginger

solu-212

ginger paralysis See jamaica ginger paralysis.

gingivitis Inflammation, swelling and bleeding of the gums; may

be due to scurvy, but most commonly the result of poor oralhygiene

gingko The maidenhair tree, Gingko biloba The seeds are edible

when roasted but may be toxic when raw Extracts from theleaves are used as a herbal remedy; they contain potentiallyactive flavonoids and terpenes, but there is limited evidence ofefficacy

gin-nan Food poisoning associated with excessive consumption ofgingko seeds, especially if uncooked

ginseng Herbal products from the roots of three species; Korean

or Chinese ginseng is Panax ginseng, Siberian is Eleutherococcus senticosus; American is P quinquefolius Reported to have an

immunostimulant action and act as a tonic, with limited evidence

of efficacy

GIP Glucose-dependent insulinotropic peptide, originallythought to act as inhibitor of gastric acid secretion based andnamed Gastric Inhibitory Peptide Like glp-1, it stimulatesinsulin secretion (hence the higher insulin response to oral than

to intravenous glucose)

See also incretins.

gipping (of fish) Partial evisceration to remove intestines but notpyloric caeca, which contain the enzymes responsible for thecharacteristic flavour of herring when it is subsequently salted

gjetost Norwegian sweet, semi-caramelised hard cheese madefrom whey Normally goat milk; mysost is similar, made from cowmilk

Composition/100 g: water 13.4 g, 1951 kJ (466 kcal), protein 9.6 g, fat 29.5 g (of which 69% saturated, 28% mono-unsaturated,3% polyunsaturated), cholesterol 94 mg, carbohydrate 42.7 g, ash4.8 g, Ca 400 mg, Fe 0.5 mg, Mg 70 mg, P 444 mg, K 1409 mg, Na

600 mg, Zn 1.1 mg, Cu 0.1 mg, Se 14.5µg, vitamin A 334µg retinol,

B10.31 mg, B21.38 mg, niacin 0.8 mg, B60.27 mg, folate 5µg, B12

2.4µg, pantothenate 3.4mg A 40g serving is a source of vitamin

A, a good source of Ca, P, pantothenate, a rich source of vitamin

Glasgow magistrate See red herring.

glass transition temperature In sugar confectionery, the ature at which a rubbery gel becomes a clear glass, a change thatdoes not involve latent heat

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gliadin A prolamin, one of the proteins that make up wheatgluten Allergy to, or intolerance of, gliadin is coeliac disease.

globins proteins that are rich in the amino acid histidine (andhence basic), relatively deficient in isoleucine Often found asthe protein part of conjugated proteins such as haemoglobin

globulins Class of proteins that are heat-coagulatable andsoluble in dilute solutions of salts; they differ from albumins inbeing relatively insoluble in water They occur in blood (serumglobulins), milk (lactoglobulins) and some plants, e.g edestinfrom hemp seed and amandin from almonds

glossitis Inflammation of the tongue; may be one of the signs ofriboflavin deficiency

GLP-1 Glucagon-like peptide-1, a peptide hormone secreted bycells of the distal ileum in response to food intake; formed bypost-synthetic modification of proglucagon Like gip it stimu-lates insulin secretion (hence the higher insulin response to oralthan to intravenous glucose)

See also incretins.

glucagon Peptide hormone secreted by the α-islet cells of thepancreas Elevates blood glucose by increasing the breakdown

of liver glycogen and stimulating gluconeogenesis

glucagon-like peptide Peptide hormone secreted by the terminalileum; increases secretion of insulin and decreases that ofglucagon

glucans Soluble undigested polysaccharides of glucose; foundparticularly in oats, barley and rye

See also fibre, soluble; non-starch polysaccharides.

glucaric acid Or saccharic acid, the dicarboxylic acid derived fromglucose

glucide (gluside) Name occasionally used for saccharin

glucitol Obsolete name for sorbitol

glucoamylase See amylase; debranching enzyme.

glucocorticoids The steroid hormones secreted by the adrenal

cortex (see adrenal glands), which regulate carbohydrate

metabolism

See also corticosteroids.

glucokinase An isoenzyme of hexokinase (EC 2.7.1.1), with a

high Km, found only in liver and β-islet cells of the pancreas Onetype of a rare form of diabetes mellitus (mody, maturity onsetdiabetes of the young) is due to a genetic defect in glucokinase

glucomannan A polysaccharide consisting of glucose and mannose

gluconeogenesis The synthesis of glucose from non-carbohydrateprecursors, such as lactate, pyruvate, glycerol and glucogenicamino acids

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gluconic acid The acid formed by oxidation of the hydroxyl group

on carbon-1 of glucose to a carboxylic acid group Also termeddextronic acid, maltonic acid and glycogenic acid

glucono-d-lactone gluconic acid lactone; liberates acid slowly,

and used in chemically leavened (aerated) bread to form carbondioxide from bicarbonate

glucosaccharic acid See saccharic acid.

glucosamine The amino derivative of glucose, a constituent of avariety of complex polysaccharides

glucosan A general term for polysaccharides of glucose, such asstarch, cellulose and glycogen

glucose A six-carbon monosaccharide sugar (hexose), with thechemical formula C6H12O6, occurring free in plant and animaltissues and formed by the hydrolysis of starch and glycogen.Also known as dextrose, grape sugar and blood sugar

The carbohydrate in blood is glucose; normal concentration

is between 4.5 and 5.5 mmol/L (80–100 mg/100 mL) In the fedstate, glucose is used for the synthesis of glycogen in liver andmuscle, as well as for synthesis of fats; in the fasting state, glyco-gen is hydrolysed as a source of glucose to maintain the bloodconcentration

Used in the manufacture of sugar confectionery when it

is sometimes known as dextrose The mixture with fructoseprevents sucrose from crystallising It is 74% as sweet as sucrose

glucose, confectioners’ Glucose syrups are known as glucose inconfectionery making (glucose is referred to as dextrose)

glucose isomerase Bacterial enzyme (EC 5.3.1.5) that catalysesisomerisation of glucose to fructose Used in the production

of fructose syrups Main commercial source is Streptomyces

spp

glucose metabolism Series of reactions in which glucose is oxidised to carbon dioxide and water as a metabolic fuel (i.e toprovide energy) The overall reaction is: C6H12O6+ 6O2→ 6CO2

+ 6H2O, yielding 16.4 kJ (3.9 kcal)/g, or 2.88 MJ (686 kcal)/mol.The first sequence of reactions does not require oxygen and isreferred to as (anaerobic) glycolysis or glucose fermentation,yielding two molecules of the three-carbon compound pyruvate.Under anaerobic conditions this can be reduced to lactic acid.Pyruvate is normally oxidised to acetyl CoA, which is then oxi-dised to carbon dioxide and water via the citric acid or Krebscycle Both glycolysis and the citric acid cycle are linked to theformation of atp from adp and phosphate, as a metabolicallyusable energy source

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