This organic acid has antioxidative activity, and is commonly used as a standard when measuring levels of phenols in foods and beverages.. Widely used in the food industry in gelling age
Trang 1Galactanases 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 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.
galactooligosac-manufacture of baked goods and other foods These
enzymes are also useful for utilization of containing wastes Also known as lactases
whey-Galactosides Glycosides formed from mixing lactose with an alcohol; on hydrolysis, galactose is
ga-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
Trang 2pickles 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 heatdur-ing, pasteurization or autoclavdur-ing 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
(60Co) or caesium-137 (137Cs) Used for sterilization
or preservation purposes Irradiation delays 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
ripen-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 (60Co) and caesium-137 (137Cs)
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 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
cold-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 nia jasminoides are used as a source of food color-
Garde-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
Trang 3being 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 combinadetec-tion 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, bacter and Vibrio, and Escherichia coli, rotavi-
Campylo-ruses and small round structured viCampylo-ruses 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
Trang 4is 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 heatdur-ing or cooldur-ing 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 tion Used in manufacture of jellies and other food gels Commonly used gelling agents include pectins, agar, guar gums and gellan gums.
gela-Gelling capacity One of the functional properties
of a substance concerned with its ability to form a gel
Gel permeation chromatography Size sion chromatography technique in which separa-
exclu-tion is based on the hydrodynamic volume of 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
mole-of their ability to penetrate the pores mole-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 soluble polymers
organic-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 ducing multiple copies of the gene of interest
pro-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 trients may affect carcinogenesis but only in indi- viduals with a genetic predisposition to cancer or a certain genetic polymorphism may impact on car-
Trang 5cinogenesis, 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 gineered foods Foods and beverages that have been
en-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 isms
microorgan-Genetically modified organisms Organisms that have been modified by genetic techniques to en-
hance their properties or confer upon them new ties Abbreviated to GM organisms or GMO
proper-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 ting may also be used Also known as DNA finger- printing.
blot-Genetic mapping Process by which the relative tions of genes on DNA molecules (usually chromo- somes) and the distances between them are deter-
posi-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
Trang 6Geniposide 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 thenticity and quality of a product Certain foods and
au-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 grass oils.
lemon-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 ture of alcoholic beverages, and in production of mushrooms.
Trang 7Germination 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 ingesInfec-tion 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 wawa-ter 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,
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 ages, including gingerbread and ginger beer Pungency is due to the presence of gingerols May
bever-also refer to related Curcuma spp such as C rhiza.
xanthor-Ginger ale xanthor-Ginger-flavoured sweetened ated beverages, often added to spirits such as
carbon-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 ing ginger and other flavourings Industrial produc-
contain-tion often does not involve fermentacontain-tion, and the tant product is usually alcohol-free and marketed as a soft drink
resul-Gingerbread Dark molasses-based cakes or 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.
bis-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 ChiJapa-nese 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 nosides.
ginse-Ginsenosides Complex mixture of saponins which are believed to be the active components of ginseng,
Panax ginseng, and are thought to be responsible for
Trang 8the 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 glossishini-ness
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 bre, low in fat and calories, and rich in vitamin A and vitamin C.
fi-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
immu-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 atic cells in response to a decrease in serum glucose Acts by promoting the conversion of liver glycogen
pancre-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 -
Trang 91,4- 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 glucosidases.
1,4-Į-Glucobrassicin Alternative term for 3-indolylmethyl glucosinolate, one of the major glucosinolates
found in vegetables of the genera Brassica and
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 prising glucose and mannose which occur naturally
com-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 lants or chelating agents in foods, beverages, food supplements, pharmaceuticals, etc Also used
acidu-as carriers for minerals in food fortification tained by the fermentation of glucose.
Ob-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 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
Ace-An important industrial microbial strain Frequently
used in biotechnological applications such as versions, biotransformations and technology in- volving biosensors Most of these processes make use of membrane-bound polyol dehydrogenases and dextran dextrinases.
biocon-Glucono-į-lactone Lactone that forms gluconic acid when dissolved in water Used as an acidulant
Trang 10and 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
oxidizeȕ-D-glucose to ȕ-D-gluconic acid and H2 O 2
Used for stabilizing foods and beverages by removing
glucose and O 2 , and preventing deterioration of
col-our and flavcol-our (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 in food
packaging, thus protecting against oxidative
deterio-ration
Glucose-6-phosphate Primary metabolite of cose in living cells Formation of glucose-6- phosphate from glucose is the first reaction in glyco- lysis and is catalysed by hexokinases.
glu-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 glucosides Polysaccharides are hydrolysed rela- tively slowly Hydrolyse carbohydrates including maltose, sucrose and starch and catalyse a variety
Į-D-of transglycosylation reactions, e.g for the sis of prebiotics.Į-Glucosidase inhibitors in foods may be useful in controlling postprandial hypergly-
synthe-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 glucosides These enzymes have a number of uses
aryl-ȕ-in the food aryl-ȕ-industry, aryl-ȕ-includaryl-ȕ-ing debitteraryl-ȕ-ing of table olives, increasing the aroma of wines, enrichment
of genistein in soy protein concentrates and lease of phenols from phenolic glycosides in plant
re-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 oxidative activity However, cyanogenic glucosides