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
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