Tài liệu Tự điển Food Science, Technology And Nutrition - Vần H pdf

Dextran gums: α-d-glucose polymers produced by Leuconos-
toc mesenteroides. Xanthan gum produced by Xanthomonas
campestris.
gum arabic (gum acacia) Exudate from the stems of Acacia spp.;
the best product comes from A. senegal. Used as thickening
agent, as stabiliser, often in combination with other gums, in gum
drops and soft jelly gums and to prevent crystallisation in sugar
confectionery.
gumbo (1) American (Creole); soup or stew made from okra,
onions, celery and pepper, flavoured with filé powder (powdered
dried sassafras leaves), and containing chicken, meat, fish or
shellfish.
(2) See okra.
gum, British Partly hydrolysed starch, dextrin.
gum, chewing See chewing gum.
gum drops (fruit gums) sugar confectionery based on sucrose
and glucose with gum arabic (hard gums) or a mixture of gela-
tine and gum arabic (soft gums).
gum tragacanth Obtained from the trees of Astralagus spp., used
as a stabiliser.
gur Mixture of sugar crystals and syrup, brown and toffee-like,
made by evaporation of juice of sugar cane; also called jaggery.
gustin zinc-containing protein associated with taste acuity.
See also hypogeusia; dysgeusia.
gut See gastrointestinal tract.
Guthrie test Test for a number of genetic diseases (especially
phenylketonuria) based on measuring the concentrations of
amino acids in a small sample of blood taken by pricking the
heel of the child a few days after birth, by biological assay using
mutated bacteria for which the amino acid is a growth factor.
Now largely superseded by chromatographic methods.

gut sweetbread See pancreas.
GYE Guinness yeast extract, see yeast extract.
gyle alcohol solution formed in the first stage of vinegar pro-
duction, 6–9% alcohol. Subsequent fermentation with Acetobac-
ter spp. converts the alcohol to acetic acid.
H
HACCP Hazard analysis of critical control points. A technique
for identification of stages in a process (e.g.in food manufacture)
where there are risks that can be anticipated, assigning a degree
of seriousness and identifying control mechanisms.
hachis Minced or chopped mixture of meat and herbs.
haddock White fish, Melanogrammus aeglefinus.
227
Composition /100g:water 79.9g,364kJ (87kcal),protein 18.9g,
fat 0.7g, cholesterol 57mg, carbohydrate 0g, ash 1.2g, Ca 33mg,
Fe 1 mg, Mg 39 mg, P 188mg, K 311mg, Na 68mg, Zn 0.4mg, Se
30.2µg,I 250µg,vitamin A 17µg RE (17µg retinal),E 0.4mg,K 0.1
mg,B
1
0.04mg,B
2
0.04mg,niacin 3.8mg,B
6
0.3mg,folate 12µg,B
12
1.2µg, pantothenate 0.1mg. A 100g serving is a source of Mg,
vitamin B
6
,a good source of P,niacin,a rich source of I,Se,vitamin
B

12
.
haem (heme) The iron-containing porphyrin that,in combination
with the protein globin, forms haemoglobin and myoglobin.It
is also part of a wide variety of other proteins, collectively known
as haem proteins, including the cytochromes.
See also protoporphyrin.
haemagglutinins (hemagglutinins) See lectins.
haematemesis (hematemesis) Vomiting bright red blood, due to
bleeding in the upper gastrointestinal tract.
haematin (hematin) Formed by the oxidation of haem; the iron is
oxidised from the ferrous (Fe
2+
) to the ferric (Fe
3+
) state.
haematinic (hematinic) General term for those nutrients, includ-
ing iron, folic acid, vitamin b
12
, required for the formation and
development of blood cells in bone marrow (the process of
haematopoiesis), deficiency of which may result in anaemia.
haematocrit (hematocrit) Packed volume of red blood cells,
expressed as fraction of the total volume of blood; determined
by centrifugation in calibrated capillary tube (haematocrit tube),
as an index of anaemia, and especially microcytic and mega-
loblastic anaemias. Not a sensitive index of iron status, because
it only falls after haemoglobin synthesis has been impaired.
haemin (hemin) The hydrochloride of haematin, derived from
haemoglobin.The crystals are readily recognisable under the

microscope and used as a test for blood.
haemochromatosis iron overload; excessive absorption and
storage of iron in the body, commonly the result of a genetic
disease, leading to tissue damage (including diabetes) and
bronze coloration of the skin. Sometimes called bronze diabetes.
haemoglobin (hemoglobin) The haem-containing protein in red
blood cells, responsible for the transport of oxygen and carbon
dioxide in the bloodstream.
See also anaemia; iron.
haemoglobin, glycated Also known as glycosylated haemoglobin
or haemoglobin A
1c
.The result of non-enzymic reaction between
glucose and ε-amino groups of lysine. Measurement of glycated
haemoglobin is used as an index of glycaemic control in diabetes
mellitus over the preceding 2–3 months; normally 3–6% of
228
haemoglobin is glycated, but when there has been prolonged
hyperglycaemia as much as 20% may be glycated.
See also glycation; maillard reaction.
haemoglobinometer (hemoglobinometer) Instrument to mea-
sure the amount of haemoglobin in blood by colorimetry.
haemolysis (hemolysis) Destruction of red blood cells by lysis of
the cell membrane; may occur in a variety of pathological con-
ditions, as a result of incorrectly matched blood transfusion or in
vitamin e deficiency.
See also anaemia, haemolytic; favism.
haemorrhagic (hemorrhagic) disease of the newborn Excessive
bleeding due to vitamin k deficiency; in most countries infants
are given vitamin K by injection shortly after birth to prevent

this rare but serious (potentially fatal) condition.
haemorrhoids (hemorrhoids) Or piles. Varicosity in the lower
rectum or anus due to congestion of the veins, caused or exac-
erbated by a low-fibre diet and consequent straining to defecate.
haemosiderin (hemosiderin) See iron storage.
Hagberg falling number Measure of α-amylase (EC 3.2.1.1)
activity of flour based on the change in viscosity of flour paste.
haggis Traditional Scottish dish made from sheep’s heart, liver
and lungs cooked and chopped with suet, onions, oatmeal and
seasoning, stuffed into a sheep’s stomach. Said to have been
originated by the Romans when campaigning in Scotland;
when breaking camp in an emergency, the food was wrapped
in the sheep’s stomach. A similar Norman-French dish was
afronchemoyle.
hair analysis Measurement of various minerals,including chromium,
selenium and zinc in hair has been proposed as an index of status,
but interpretation of the results is confounded by adsorption of
minerals onto the hair from shampoo,etc.
hake A white fish, Merluccius bilinearis.
hakka muggies Shetland; seasoned cod liver and oatmeal boiled
in the stomach (muggie) of a fish.
See also haggis.
halal Food conforming to the Islamic (Muslim) dietary laws.Meat
from permitted animals (in general grazing animals with cloven
hooves, and thus excluding pig meat) and birds (excluding birds
of prey). The animals are killed under religious supervision by
cutting the throat to allow removal of all blood from the carcass,
without prior stunning. Food that is not halal is haram.
haldi See turmeric.
half-life (1) The time taken for half of a given protein to be

replaced. Proteins are continuously being degraded and replaced
229
even in the mature adult, and the half-life is used as a quantita-
tive measure of this dynamic equilibrium. The values of half-life
of different proteins range from a few minutes or hours for
enzymes which control the rate of metabolic pathways, to almost
a year for structural proteins such as collagen. The average half-
life of human liver and serum proteins is 10 days, and of the total
body protein is 80 days.
(2) Of radioactive isotopes, the time in which half of the
original material undergoes radioactive decay.
half-products See preforms.
halibut A white fish, Hippoglossus spp.
Composition /100g: water 70g, 779kJ (186kcal), protein 14.4g,
fat 13.8g (of which 20% saturated, 69% mono-unsaturated, 11%
polyunsaturated), cholesterol 46mg, carbohydrate 0g, ash 1g,
Ca 3mg, Fe 0.7mg, Mg 26mg, P 164mg, K 268mg, Na 80mg, Zn
0.4mg, Se 36.5µg, I 47µg, vitamin A 17µg retinol, E 0.9 mg, K 0.1
mg, B
1
0.06mg, B
2
0.08mg, niacin 1.5mg, B
6
0.42mg, folate 1µg,
B
12
1µg, pantothenate 0.3mg. A 100g serving is a source of
vitamin a good source of P, vitamin B
6

,a rich source of I, Se,
vitamin B
12
.
Halibut liver oil is one of the richest natural sources of vita-
mins A and D, containing 50mg vitamin A and 80µg vitamin D
per gram.
halophiles (halophilic bacteria) Able to grow at up to 25% salt.
The growth of colonic bacteria is inhibited at 8–9% salt,
Clostridia at 7–10%, food poisoning staphylococci at 15–20%
and Penicillium at 20%. Film-forming yeasts can grow in 24%
salt.
Halphen test For the presence of cottonseed oil in other oils and
fats.
halvah (halva, halwa, halawa, chalva) (1) A sweetmeat composed
of an aerated mixture of glucose, sugar and crushed sesame
seeds; because of the seeds, the sweet contains 25% fat.
(2) Indian desserts of various types, made from carrot,
pumpkin or banana, sweetened and flavoured.
halverine Name sometimes given to low-fat spreads with less
than the statutory amount of fat in a margarine.
ham The whole hind leg of the pig, removed from the carcass and
cured individually. Hams cured or smoked in different ways
have different flavours. Green ham has been cured but not
smoked.
Composition /100g: water 67g, 682kJ (163kcal), protein 16.6g,
fat 8.6g (of which 36% saturated, 54% mono-unsaturated, 10%
polyunsaturated), cholesterol 57mg, carbohydrate 3.8g, fibre
1.3g, ash 3.7g, Ca 24mg, Fe 1mg, Mg 22mg, P 153mg, K 287mg,
230

Na 1304mg, Zn 1.4mg, Cu 0.1mg, Mn 0.6mg, Se 20.7µg, I 7 µg,
vitamin E 0.1mg,B
1
0.63mg,B
2
0.18mg,niacin 2.9mg, B
6
0.33mg,
folate 7µg, B
12
0.4µg, pantothenate 0.4mg, C 4mg.A 60g serving
(2 slices) is a source of Mn, P, Se, a good source of vitamin B
1
,
B
12
.
hamburger Or Hamburg steak, also known as beefburger. A flat
patty made from ground (minced) beef, seasoned with salt,
pepper and herbs, and bound with egg and flour. Commercial
beefburgers are usually 80–100% meat, but must by law (in UK)
contain 52% lean meat, of which 80% must be beef. Cereal,
cereal fibre or bean fibre may be added as filler or ‘meat
extender’.
Hammarsten’s casein See casein.
hammer mill Continuous process mill in which material is pow-
dered by impact from a set of hammers.A modified hammer mill
using knives instead of hammers is used to shred food.
hand of pork The foreleg of pork; usually salted and boiled.
hangover Headache and feeling of malaise resulting from exces-

sive consumption of alcoholic beverages.The severity differs
with different beverages and is not due to the toxic effects of
alcohol alone, but to the presence of higher alcohols and esters
(collectively known as congeners or fusel oil), the substances
that give different beverages their distinctive flavours.
Hansa can An all-aluminium can (developed in Germany) with
easily opened ends.
Hansa herring Salted herring, dating from 13th century, pre-
pared by the fishermen of the Hanseatic League, the ports of the
Baltic and north German rivers, after the fish had been landed,
as opposed to fish salted at sea.
haram Food forbidden by Islamic law. See also halal.
harasume Japanese; transparent noodles made from mung bean
paste.
hardening of oils See hydrogenation.
hardness of water See water hardness.
hare Game animal, similar to rabbit but larger; caught wild but
not farmed commercially. Lepus europaeus is the common hare;
some 20 Lepus spp. occur in Europe.
Hartnup disease Rare genetic defect of tryptophan transport,
leading to development of pellagra.
Harvard standards Tables of height and weight for age used as
reference values for the assessment of growth and nutritional
status in children, based on data collected in the USA in the
1930s. Now replaced by the NCHS (US National Center for
Health Statistics) standards.
See also nchs standards; tanner standards.
231
HarvestPlus International research initiative coordinated by the
International Center for Tropical Agriculture and the Interna-

tional Food Policy Research Institute to develop micronutrient-
rich dietary staples (initially beans, cassava, maize, rice, sweet
potatoes and wheat) by conventional plant breeding techniques.
Web site />hash Dish of cooked meat reheated in highly flavoured sauce. In
the USA canned corned beef is known as corned beef hash.
haslet (harslet) Old English country dish made from pig’s offal
(heart, liver, lungs and sweetbreads) cooked in small pieces with
seasoning and flour. Also known as pig’s fry.
hasty pudding English, 16th century; made from flour, milk,
butter and spices, which since they were usually readily available,
could be quickly made into the pudding for unexpected visitors.
Made in the USA with maize (corn) flour instead of wheat flour.
Hausa groundnut legume grown in West Africa, Kerslingiella
geocarpa.
haybox cooking The food is cooked for only a short time, then
placed in a well-lagged container, the haybox, where it remains
hot for many hours, so cooking continues without further use of
fuel. Also known as the fireless cooker.
Hay diet A system of eating based on the concept that carbohy-
drates and proteins should not be eaten at the same meal, for
which there is no scientific basis, originally proposed by William
Hay in 1936. It ignores the fact that almost all carbohydrate-rich
foods also contain significant amounts of protein. In any case, in
the absence of adequate carbohydrate, protein is oxidised as a
metabolic fuel and therefore not available for tissue building.
Also called combining diet or food combining.
hazard analysis The identification of potentially hazardous ingre-
dients, storage conditions, packaging, critical process points and
relevant human factors which may affect product safety or
quality.

haze Term in brewing to indicate cloudiness of beer. Chill haze
appears at 0°C and disappears at 20°C; permanent haze remains
at 20°C but there is no fundamental difference. Caused by gums
derived from the barley, leucoanthocyanins and tannins from the
malt and hops, and glucose, pentoses and amino acids.
See also chillproofing.
hazel nut Fruit of the tree Corylus avellana; cultivated varieties
include Barcelona nut, cob nut and filbert (C. maxima).
Composition /100g: (edible portion 46%) water 5.3g, 2629kJ
(628kcal), protein 14.9g, fat 60.8g (of which 8% saturated, 79%
mono-unsaturated, 14% polyunsaturated), carbohydrate 16.7g
(4.3g sugars), fibre 9.7g, ash 2.3g, Ca 114mg, Fe 4.7mg, Mg
232
163mg, P 290mg, K 680mg, Zn 2.5mg, Cu 1.7mg, Mn 6.2mg, Se
2.4µg, vitamin A 1µg RE (106µg carotenoids), E 15mg, K
14.2mg, B
1
0.64mg, B
2
0.11mg, niacin 1.8mg, B
6
0.56mg, folate
113µg, pantothenate 0.9mg, C 6mg. A 10g serving (10 nuts) is a
source of Cu, vitamin E, a good source of Mn.
Hazelnut oil is 8% saturated, 82% mono-unsaturated, 11%
polyunsaturated; contains 47.2mg vitamin E /100g.
HCFCs Hydrochlorofluorocarbons, see refrigerants.
HDL High-density lipoprotein, see lipoproteins, plasma.
headcheese Mock brawn.
headspace The space between the surface of a food and the

underside of the lid in a container.
health foods Substances whose consumption is advocated by
various reform movements, including vegetable foods, whole
grain cereals, food processed without chemical additives, food
grown on organic compost, ‘magic’ foods (bees’ royal jelly,
kelp, lecithin, seaweed, etc.) and pills and potions. Numerous
health claims are made but rarely is there any evidence to
support these claims.
healthy US legislation permits a claim of ‘healthy’ for a food that
is low in fat and saturated fat, and contains no more than
480mg of sodium and 60mg of cholesterol per serving.
heart Both lamb and ox hearts are eaten.
Lamb, composition /100g: (edible portion 78%) water 77 g,
511kJ (122kcal), protein 16.5g, fat 5.7 g (of which 51% saturated,
36% mono-unsaturated, 13% polyunsaturated), cholesterol
135mg, carbohydrate 0.2g, ash 0.9g, Ca 6mg, Fe 4.6mg, Mg
17mg, P 175mg, K 316mg, Na 89mg, Zn 1.9 mg, Cu 0.4mg,
Se 32µg, vitamin B
1
0.37mg, B
2
0.99mg, niacin 6.1mg, B
6
0.39mg,
folate 2µg, B
12
10.3µg, pantothenate 2.6mg, C 5mg. A 100g
serving is a source of Zn, vitamin B
6
,a good source of P, vitamin

B
1
,a rich source of Cu, Fe, Se, vitamin B
2
, niacin, B
12
,
pantothenate.
Ox, composition /100g: (edible portion 71%) water 77g,
469kJ (112kcal), protein 17.7g, fat 3.9 g (of which 47% saturated,
37% mono-unsaturated, 17% polyunsaturated), cholesterol
124mg, carbohydrate 0.1g, ash 1.1g, Ca 7mg, Fe 4.3mg, Mg
21mg, P 212mg, K 287mg, Na 98mg, Zn 1.7mg, Cu 0.4mg, Se
21.8µg, vitamin E 0.2mg, B
1
0.24mg, B
2
0.91mg, niacin 7.5mg, B
6
0.28mg, folate 3µg, B
12
8.6µg, pantothenate 1.8mg, C 2mg. A
100g serving is a source of Mg, vitamin a good source of Zn,
vitamin B
6
,a rich source of Cu, Fe, P, Se, vitamin B
1
,B
2
, niacin,

B
12
, pantothenate.
heartburn A burning sensation in the chest usually caused by
reflux (regurgitation) of acid digestive juices from the stomach,
233
into the oesophagus. A common form of indigestion, treated by
antacids.
heart of palm Edible inner part of the stem of cabbage palm.
Composition /100g: water 69.5g, 481kJ (115kcal), protein
2.7g, fat 0.2g, carbohydrate 25.6g (17.2g sugars), fibre 1.5g, ash
2g, Ca 18mg, Fe 1.7mg, Mg 10 mg, P 140mg, K 1806mg, Na
14mg, Zn 3.7mg, Cu 0.6mg, Se 0.7µg, vitamin A 3µg RE (41µg
carotenoids), E 0.5mg, B
1
0.05mg, B
2
0.18mg, niacin 0.9mg, B
6
0.81mg, folate 24µg, C 8mg.
heart sugar Obsolete name for inositol.
heat capacity (or thermal capacity) The ratio of heat supplied to,
or removed from, a substance and its change in temperature.
Specific heat capacity is expressed per unit mass; molar heat
capacity per mol.
heat exchanger Equipment for heating or cooling liquids rapidly
by providing a large surface area for the rapid and efficient trans-
fer of heat. Used, e.g., for continuous pasteurisation and subse-
quent cooling.
heath hen game bird,Tympanuchus cupido cupido, native to New

England.
heating, direct Processes in which the heat (and products of com-
bustion) from burning fuel come into direct contact with the
food, as in baking ovens and kiln driers.
heating, indirect Processes in which there is a heat exchanger
(e.g. metal plates, steam or hot water in pipes) between the
burning fuel and the food.
heat, latent The amount of heat necessary to change a given mass
of a substance from one state to another (i.e. melting of a solid
or boiling of a liquid to yield vapour), without a change in its
temperature.
heat of combustion energy released by complete combustion, as
for example, in the bomb calorimeter. See energy conversion
factors.
heat pump System of producing heat or cold by compression or
expansion of air, also known as Joule cycle or air cycle. Modern
systems can produce temperatures as low as −80°C or as high as
200°C and are being introduced as an environmentally friendly
method of refrigeration, replacing fluorocarbon and chloro-
fluorocarbon refrigerants.
heat, sensible Heat used to raise the temperature of a food or
removed during cooling, without a change in phase.
heat, specific The amount of heat that accompanies a unit change
in temperature by a unit mass of material.
heat transfer Occurs in three ways: radiation (transfer by infra-
red electromagnetic waves), conduction (movement of heat
234
through a solid material) and convection (transfer by movement
of molecules through a fluid as a result of lower density at higher
temperatures).

heat transfer, steady-state Heating or cooling when there is no
change in temperature at any specific location.
heat transfer, unsteady-state Heating or cooling where the tem-
perature of the food and/or the heating or cooling medium are
constantly changing.
hedonic scale Term used in tasting panels where the judges indi-
cate the extent of their like or dislike for the food.
heel-prick test See guthrie test.
Hegsted score Method of expressing the lipid content of a diet,
calculated as 2.16 × % energy from saturated fat −1.65 × %
energy from polyunsaturated fat −0.0677 × mg cholesterol. See
also Keys score.
Helicobacter pylori Bacterium commonly infecting the gastric
mucosa. The underlying cause of ulcers, and implicated in
the development of gastric cancer. Formerly classified as
CAMPYLOBACTER.
helminths Various parasitic worms, including flukes, tapeworms
and nematodes.
hemicelluloses Complex carbohydrates included as dietary
fibre, composed of polyuronic acids combined with xylose,
glucose, mannose and arabinose. Found together with cellulose
and lignin in plant cell walls; most gums and mucilages are
hemicelluloses.
hemoglobin American spelling of haemoglobin; similarly,
hematin = haematin, heme = haem, hemosiderin = haemosiderin.
hemp seed Fruits of Cannabis sativa, eaten toasted in China, as a
condiment in Japan; the oil is added to salad dressings and dips,
but is not suitable for cooking. The seed contains little or no
cannabinoids.
HEPA filter See high efficiency particulate air filter.

heparin Complex carbohydrate (glycosaminoglycan) from mast
cells in liver, lung, muscle, heart and blood which prevents blood
coagulation by activating antithrombin III, and so inhibiting the
conversion of prothrombin to thrombin. In vivo cleared rapidly
from the bloodstream, but in vitro 10mg prevents the coagula-
tion of 100mL of blood.
hepatic encephalopathy Impairment of brain function, leading to
coma, as a result of liver disease.
hepatitis Inflammatory liver disease, characterised by jaundice,
abdominal pain and anorexia. May be due to bacterial or viral
infection, alcohol abuse or various toxins. Treatment is usually
conservative, with a very low fat diet (secretion of bile is
235
impaired) and complete abstinence from alcohol. Even after
recovery, people may continue to be carriers of the virus, espe-
cially for hepatitis B and C, which are transmitted through blood
and other body fluids. Liver cancer and cirrhosis are more
common among people who have suffered from hepatitis B or C.
hepatoflavin Name given to a substance isolated from liver, later
shown to be riboflavin.
hepatolenticular degeneration See wilson’s disease.
hepatomegaly Enlargement of the liver as a result of congestion
(e.g. in heart failure), inflammation or fatty infiltration (as in
kwashiorkor).
herbs Soft-stemmed aromatic plants used fresh or dried to
flavour and garnish dishes, and sometimes for medicinal effects.
Not clearly distinguished from spices, except that herbs are
usually the leaves or the whole of the plant, while spices are only
part of the plant, commonly the seeds, or sometimes the roots or
rhizomes.

herb tea See tisane.
Hermesetas
TM
See saccharin.
hermetically sealed container A package that is designed to be
secure against entry of micro-organisms and maintain the com-
mercial sterility of its contents after processing.
herring Oily fish, Clupea harengus; young herrings are sild. Sprat
is Clupea sprattus; young are brislings. Pilchard is Clupea
pilchardus; young are sardines. Kippers,bloaters and red herrings
are salted and smoked herrings; bucklings are hot-smoked her-
rings. gaffelbitar are preserved herring.
Composition /100g: water 72g, 661 kJ (158 kcal), protein 18g,
fat 9g (of which 26% saturated, 47% mono-unsaturated, 27%
polyunsaturated), cholesterol 60mg, carbohydrate 0g, ash 1.5g,
Ca 57mg, Fe 1.1mg, Mg 32mg, P 236mg, K 327mg, Na 90mg, Zn
1mg, Cu 0.1mg, Se 36.5µg, I 29µg, vitamin A 28 µg retinol, E
1.1mg, K 0.1mg, B
1
0.09mg, B
2
0.23mg, niacin 3.2mg, B
6
0.3mg,
folate 10µg, B
12
13.7µg, pantothenate 0.6mg, C 1mg. A 100g
serving is a source of I, vitamin E, B
2
, niacin, B

6
,a good source
of P, a rich source of Se, vitamin B
12
.
herring, liquefied herring reduced to liquid state by enzyme
action at slightly acid pH; used as protein concentrate for animal
feed.
hesperidin A flavonoid found in the pith of unripe citrus fruits;
a glucorhamnisode of the flavonone hesperin.At one time called
vitamin p, since it affects the fragility of the capillary walls,
although there is no evidence that it is a dietary essential.
Hess test A test for capillary fragility in scurvy.A slight pressure
is applied to the arm for 5min when a shower of petechiae (small
236
blood spots) appear on the skin below the area of application in
vitamin C deficient subjects.
heterofermentative Of micro-organisms, producing more than
one main metabolic product. See also homofermentative.
heterophysiasis Intestinal infestation with the parasitic fluke
Heterophyes heterophyes after consumption of raw fish contain-
ing the larval stage.
heteropolysaccharide polysaccharide containing more than one
type of monosaccharide.
heterosides See holosides.
heterotrophes See autotrophes.
hexamethylene tetramine Preservative (fungicide), E-239. Also
known as hexamine.
hexamic acid Cyclohexyl sulphamic acid, the free acid of
cyclamate.

hexamine See hexamethylene tetramine.
hexokinase The enzyme (EC 2.7.1.1) that catalyses the phospho-
rylation of glucose to glucose 6-phosphate. See also
glucokinase.
hexosans polysaccharides of hexose sugars, including starch,
glycogen, cellulose and hemicellulose.
hexose monophosphate shunt The pentose phosphate pathway of
glucose metabolism.
hexoses Six-carbon monosaccharide sugars such as glucose or
fructose.
hexuronic acid The acid derived from a hexose sugar by oxida-
tion of the hydroxyl group on carbon-6. Originally proposed as
a name for ascorbic acid.The hexuronic acid derived from
glucose is glucuronic acid.
HFAs Hydrofluoroalkanes, see refrigerants.
HFCs Hydrofluorocarbons, see refrigerants.
HFCS High-fructose corn syrup, see syrup, fructose.
HF heating High-frequency heating, see microwave cooking.
HFN See hagberg falling number.
HGH Human growth hormone (somatotrophin).
HHP High hydrostatic pressure, a technology proposed for
preservation of foods by inactivation of enzymes without
heating; requires pressures of the order of 8–900MPa.
hiatus hernia Protrusion of a part of the stomach upwards
through the diaphragm. The condition occurs in about 40% of
the population, most people suffering no ill effects; in a small
number of people there is reflux of stomach contents into the
oesophagus, causing heartburn.
See also gastrointestinal tract.
hickory nut North American walnut, Carya spp.

237
Composition /100g: (edible portion 32%) water 2.7g, 2750kJ
(657kcal), protein 12.7g, fat 64.4g (of which 11% saturated, 53%
mono-unsaturated, 36% polyunsaturated), carbohydrate 18.3g,
fibre 6.4g, ash 2g, Ca 61 mg, Fe 2.1mg, Mg 173mg, P 336 mg, K
436mg, Na 1 mg, Zn 4.3mg, Cu 0.7mg, Mn 4.6mg, Se 8.1µg,
vitamin A 7µg RE, B
1
0.87mg, B
2
0.13mg, niacin 0.9mg, B
6
0.19mg,folate 40µg, pantothenate 1.7mg, C 2mg.An 18g serving
(3 nuts) is a source of vitamin B
1
,a rich source of Mn.
high-density lipoproteins (HDL) One of the classes of plasma
lipids.
high-efficiency particulate air (HEPA) filter A filter of unwoven
fibrous material to remove micro-organisms from air or other
gases.
high-frequency heating See microwave cooking.
high-fructose corn syrup See syrup, fructose.
high in EU legislation states that for a food label or advertising
to bear a claim that it is ‘high in’ a nutrient it must contain 50%
more of the claimed nutrient than a similar product for which no
claim is made. Claims may also be made for foods containing
more than 12g of protein, 6g of dietary fibre or more than 30%
of the labelling reference amount of a vitamin or mineral /100g
(see Table 2 of the Appendix).

US legislation permits a claim of ‘high in’ for foods containing
more than 20% of the daily value for a particular nutrient in a
serving. For a claim that a food is ‘higher in’ a nutrient it must
contain at least 25% more of the claimed nutrient than a similar
food for which no claim is made.
high-performance (high-pressure) liquid chromatography, HPLC
An extremely sensitive analytical technique, typically able to
separate and measure nanogram or smaller amounts of com-
pounds in 10–100µL samples.
high-pressure processing Use of pressures of the order of 300–
400MPa (45000 to 60000psi), causing irreversible denaturation
of proteins, and hence inactivation of micro-organisms and
insects and their eggs, without the changes in flavour and texture
of the food associated with heat treatment.
high-ratio fats, shortenings See fat, superglycerinated.
high-ratio flour See flour, high-ratio.
high-temperature short-time treatment (HTST) Sterilisation by
heat for times ranging from a few seconds to minutes; usually
applied to flow sterilisation, in which the process time is less than
about 1min; based on the fact that at higher temperatures bac-
teria are destroyed more rapidly than damage occurs to nutri-
ents and texture.
238
hindle wakes Old English (14th century) method of cooking
chicken, stuffed with fruit and spices, including prunes. Possibly
a corruption of hen de la wake (feast).
HIPEF High-intensity pulsed electric field processing for non-
thermal destruction of micro-organisms and inactivation of
enzymes by rapid discharge of a high-voltage electric field.
Hirschsprung’s disease Congenital failure of development of the

nerve network of the lower colon or rectum, so that it neither
expands nor conducts the contents of the bowel, which therefore
accumulate in, and distend, the upper colon.
Hi-soy
TM
Full-fat soya flour.
histamine The amine formed by decarboxylation of the amino
acid histidine, found in cheese, beer, chocolate, sauerkraut and
wine. Excessive release of histamine from mast cells is responsi-
ble for many of the symptoms of allergic reactions. Stimulates
secretion of gastric acid, and administration of histamine is used
as test for achlorhydria.
histamine receptor antagonists Inhibitors of the histamine H
2
receptor, including cimetidine, ranitidine, famotidine and nisati-
dine, are used in treatment of gastric ulcers; they act to reduce
secretion of gastric acid in response to hormone or nerve
stimulation.
histidinaemia genetic disease due to a lack of histidase (EC
4.3.1.3), leading to impaired metabolism of the amino acid
histidine. If untreated leads to mental retardation and nervous
system abnormalities. Treatment is by feeding a diet very low in
histidine.
histidine An essential amino acid, abbr His (H), M
r
155.2, pK
a
1.80, 6.04 (imidazole), 9.76, codons CAPy.
histidine load test See figlu test.
histones Proteins rich in arginine and lysine, soluble in water but

not dilute ammonia. They occur mainly in the cell nucleus and
are concerned with the super-coiling and regulation of DNA.
HLB value See hydrophile–lipophile balance.
HMG CoA reductase Hydroxymethylglutaryl CoA reductase
(EC 1.1.1.34), the first and rate-limiting enzyme of cholesterol
synthesis. The statins are a family of HMG CoA reductase
inhibitors used to treat hypercholesterolaemia.
HMT See hexamethylene tetramine.
Hobart mixer First electric mixing machine for bakeries,
patented in 1918 by Herbert Johnston, working for Hobart
Manufacturing Co.
hochoshi Japanese; cutting specialists, groups of people with their
own secret methods of cutting fish, meat and vegetables. During
239
the 12th century ceremonial cutting of food became a spectacle
for Japanese nobility.
hock (1) Generic term for white wines from the Rhine region of
Germany, known in USA as Rhine wines; bottled in brown glass,
to distinguish from Moselle wines (in green glass).
(2) The knuckle of pork; also used in USA for foreleg pork
shank.
hodge podge Victorian; stew made from left-over cooked meat
with vegetables.
hogget One-year-old sheep. See lamb.
hogshead A traditional UK measure of volume or size of barrel:
for beer or cider contains 54 gallons (243L); for wine contains
52
1
/
2

gallons (236L).
hoki A white fish (Macruronus novaezealandiae);New Zealand’s
most abundant commercial fish species. Also known as whiptail,
blue hake or blue grenadier.
holocellulose Mixture of cellulose and hemicellulose in wood,
the fibrous residue that remains after the removal of lignin and
minerals.
holoenzyme An enzyme protein together with its coenzyme or
prosthetic group.
See also enzyme activation assays.
holosides Complex carbohydrates that yield only sugars on
hydrolysis, as distinct from heterosides, which yield other sub-
stances as well as sugars on hydrolysis, e.g. tannins, anthocyanins,
nucleosides.
hominy Prepared maize kernels, also known as samp. Lye hominy
– pericarp and germ removed by soaking in caustic soda. Pearled
hominy – degermed hulled maize. Corn grits are ground hominy.
homocysteine An amino acid formed as an intermediate in the
metabolism of methionine; demethylated methionine; M
r
117.2,
pK
a
2.22, 8.87, 10.86 (—SH). Does not occur in foods to any sig-
nificant extent, and not generally considered to be of nutritional
importance.
High blood homocysteine (possibly a result of poor folic acid,
vitamin b
2
, b

6
and b
12
status) has been implicated in the develop-
ment of atherosclerosis and heart disease, associated with a
genetic polymorphism in methylene tetrahydrofolate reduc-
tase, EC 1.7.99.5).
homocystinuria A genetic disease caused by lack of cystathion-
ine synthetase (EC 4.2.1.22), leading to impaired conversion of
the amino acid methionine to cysteine, characterised by excre-
tion of homocysteine and its derivatives. May result in mental
retardation and early death from atherosclerosis and coronary
thrombosis if untreated, as well as fractures of bones and dislo-
240
cation of the lens of the eye. Treatment (which must be contin-
ued throughout life) is either by feeding a diet low in methion-
ine and supplemented with cysteine or, in some cases, by
administration of high intakes of vitamin b
6
(about 100–500 times
the normal requirement).
homofermentative Of micro-organisms, producing only one main
metabolic product.
See also heterofermentative.
homogenisation emulsions usually consist of a suspension of
globules of varying size. Homogenisation reduces these globules
to a smaller and more uniform size. In homogenised milk the
smaller globules adsorb more protein, which acts as a stabiliser,
and the cream does not rise to the top.
homogenisers Equipment for preparation and refinement of

emulsions; five main types. High-speed mixers rely on shearing
forces developed by rotating blades. Pressure homogenisers force
the mixture of liquids through a narrow aperture under high pres-
sure to induce shear forces by turbulence. Colloid mills are disc
mills with a very narrow clearance between the discs. Ultrasonic
homogenisers use high-frequency sound waves (18–20kHz)
giving a cavitation force of 10 tonnes/cm
2
causing alternate cycles
of compression and tension, forming emulsions of droplet size
1–2µm. The mixture is pumped through the homogeniser at a
pressure of 340–1400kPa. Hydroshear homogenisers and
microfluidisers feed the liquid mixture into a double cone shaped
chamber at high speed to create shear forces.
homopantothenic acid Pantoyl-γ-aminobutyric acid,a homologue
of pantothenic acid, reported to enhance cholinergic function in
the central nervous system, and used to improve cognitive func-
tion in Alzheimer’s disease.
honey Syrupy liquid made by bees (the honey bee is Apis mellif-
era) from the nectar of flowers (which is essentially sucrose).The
flavour and colour depend on the flowers from which the nectar
was obtained and the composition varies with the source. If the
ratio of fructose:glucose is high, there is a tendency for the
honey to crystallise. Comb honey is stored by bees in cells of
freshly built broodless combs and sold in the comb; drained
honey is drained from decapped combs.
honey berry Variety of raspberry.
honeydew honey During periods of prolonged drought, bees may
supplement their nectar supplies with honeydew, the sweet fluid
excreted on leaves by leaf-sucking insects. The resultant honey

is dark, with an unpleasant taste.
honeydew melon See melon.
honeyware See badderlocks.
241
hontarako Japanese; salted and dried cod roe.
hookworm Intestinal parasitic nematodes (Ancyclostoma duode-
nale and Necator americanus); infestation causes severe damage
to the intestinal wall, leading to blood loss, and is a common
cause of iron deficiency and anaemia.
hopanthate See homopantothenic acid.
hopper Indian; steamed batter cake made from rice flour mixed
with coconut water and allowed to undergo lactic acid bacterial
and yeast fermentation overnight.
hops Perennial climbing plant,Humulus lupulus; the dried female
flowers contain bitter aromatic acids (humulones and isohumu-
lones) and essential oils, and are added to beer both to pre-
serve it and enhance the flavour.The tender shoots may be eaten
as a vegetable.
hordein A protein in barley; one of the prolamins.
hordenin Alkaloid found in germinated barley, sorghum and
millet which can cause hypertension and respiratory inhibition.
Horlicks
TM
A preparation of malted dried milk, for consumption
as a beverage when added to milk.
hormesis The dose response to a toxin or nutrient that shows a
stimulation or beneficial effect at low levels and inhibition or an
adverse effect at higher levels.
hormones Compounds produced in endocrine glands, and
released into the bloodstream, where they act as chemical mes-

sengers to affect other tissues and organs.
hormones, human Originally the hormones extracted from
human tissues, used therapeutically; now applied to proteins such
as insulin and growth hormone produced in micro-organisms
into which the human gene has been introduced; correctly known
as recombinant human hormones.
hormones, sex Male hormones, or androgens, include testos-
terone,dihydrotestosterone and androsterone; female hormones,
or oestrogens, include oestradiol, oestrone and progesterone.
Chemically, all are steroids, derived from cholesterol.The syn-
thetic female hormones stilboestrol and hexoestrol have similar
biological activities to the oestrogens, but are quite different
chemically. Apart from clinical use, oestrogens have been used
for chemical caponisation (see capon) of cockerels and to
enhance the growth rate of cattle.
horse bread Medieval English; bread made with any cereal to
hand, as well as peas and beans.
horseradish The root of Armoracia lapathifolia. Pungency is
caused by volatile oils. Used as a condiment,usually as a creamed
sauce or grated and mixed with beetroot.
horseradish tree See moringa.
242
Hortvet freezing test See milk, freezing-point test.
hot break Coagulation and precipitation of high molecular
weight proteins during the boiling of wort for beer production.
Also known as trub.
Hot Springs Conference International Conference held in 1943
at which the Food and Agriculture Organisation (FAO) of the
United Nations originated.
Hovis

TM
A mixture of brown flour and wheat germ; from Latin
hominis vis, strength of man; originally, in the 1880s, called
Smith’s Old Patent Germ Bread. Now a trade name for various
types of bread and flour.
Howard mould count Standardised microscope technique for
measuring mould contamination.
howtowdie Scottish; boiled chicken with poached egg and
spinach.
HPLC See high-performance (high-pressure) liquid
chromatography.
hrisa North African condiment, a mixture of pepper and cumin.
HSH Hydrogenated starch hydrolysates, see syrup,
hydrogenated.
5HT See 5-hydroxytryptamine.
HTST See high-temperature short-time treatment.
huckleberry Wild north American berry, the fruit of Gaylussacia
baccata and other species, named after the French chemist Gay-
Lussac (1778–1850).
huff paste Northern British name for pastry made from suet,
flour and water, used to enclose meat, fish or poultry while
baking.
hull See husk.
humble pie See umbles.
humectants Substances such as glycerol, sorbitol, invert sugar
(see sugar, invert), honey which prevent loss of moisture from
foods, especially flour confectionery, which would make them
unappetising; also prevent sugar crystallising and prevent growth
of ice crystals in frozen foods. Also used in other products such
as tobacco, inks and glues.

humidification The process of increasing the water vapour
content (humidity) of air.
humidity The water content of air. The weight of water per unit
weight of air is the absolute or specific humidity. Saturation
humidity is the absolute humidity of air that is saturated with
water vapour at a given temperature. Relative humidity is the
degree of saturation: the ratio of water vapour pressure in the
atmosphere to water vapour pressure that would be exerted by
pure water at the same temperature.
243
humidity, absolute (or specific) The water vapour content of
moist air, usually expressed on a dry-weight basis, e.g. kilograms
of water vapour per kilogram of dry air. Sometimes expressed
on a volume basis, e.g.kilograms of water vapour per cubic metre
of dry air.
humid volume The volume of moist air containing unit mass of
dry air at a pressure of one atmosphere and a specified
temperature.
hummus Middle Eastern hors d’oeuvre; a purée of chickpeas and
tahini with garlic, oil and lemon juice.
humulones Bitter aromatic acids (humulone, cohumulone and
adhumulone) in hops, used to flavour and preserve beer. Con-
verted to isohumulones during boiling of the wort. Also known
as α-acids, to distinguish them from the lupulones (β-acids).
hurdle technology The concept of mild but effective food preser-
vation based on considering all the different factors that inhibit
(or act as hurdles to) the growth of spoilage organisms.
hursting mill Horizontal stone grinders formerly used for grain
milling.
husk (or hull) The outer woody cellulose covering of seeds and

grains. In wheat it is loosely attached and removed during thresh-
ing; in rice it is firmly attached. High in fibre content and of
limited use as animal feed.
HVP Hydrolysed vegetable protein; used as a flavour enhancer.
hyaluronidase Enzyme that catalyses random cleavage of 1,4
links (EC 3.2.1.35) or 1,3 links (EC 3.2.1.36) between glucuronic
acid and N-acetylglucosamine in hyaluronic acid. Injected under
the skin of poultry before slaughter to enhance tenderness and
flavour.
See also tenderisers.
hydrocooling Vegetables are washed in cold water, then sub-
jected to vacuum while still wet. The evaporation of the water
chills the vegetables for transport. Also applied to vegetables
washed in ice-water without vacuum treatment.
hydrodyne process Method of tenderising meat in which it is sub-
jected to supersonic shock waves generated under water by a
small explosive charge to shatter the fibres without affecting its
other properties; faster than other methods.
hydrogen Formed in small amounts by intestinal bacterial fer-
mentation; measurement of exhaled hydrogen on the breath pro-
vides a sensitive way of diagnosing disaccharide intolerance.
hydrogenation Conversion of liquid oils to semi-hard fats by the
addition of hydrogen across carbon–carbon double bonds; used
for margarines and shortenings intended for bakery products.
See fatty acids, unsaturated.
244
hydrogen peroxide Antimicrobial agent, H
2
O
2

. Readily loses
active oxygen, the effective sterilising agent, forming water. Can
be used at 0.1% to preserve milk (Buddeised milk, not per-
mitted in the UK), but destroys vitamin C, methionine and
tryptophan.
hydrogen swells See swells.
hydrolyse To split a complex compound into its constituent parts
by the action of water, either enzymically or catalysed by the
addition of acid or alkali. Hence hydrolysis.
hydropathy Of proteins, their relative preferences for aqueous
versus non-polar environments; the extent to which they are
hydrophilic or hydrophobic.
hydrophile–lipophile balance (HLB value) The ratio of
hydrophilic to hydrophobic groups on the molecules of an
emulsifier.
hydrophilic A solute that will dissolve in water and other polar
solvents.
hydrophobic A solute that will dissolve in non-polar solvents, but
not in water.
hydroponics The practice of growing plants without soil in a solu-
tion of inorganic salts.
hydrostatic steriliser Continuous steriliser in which the process is
carried out under sufficient depth of water to maintain the
required pressure. Used for continuous sterilisation of canned
foods on a large scale.
hydrotalcite Aluminium magnesium carbonate/hydroxide
hydrate; used as an antacid.
hydroxocobalamin See vitamin b
12
.

hydroxyapatite Calcium orthophosphate hydroxide, the main
mineral of bones, Ca
10
(PO
4
)
6
(OH)
2
.
hydroxybenzoic acid esters See parabens.
hydroxycholecalciferol See vitamin d.
hydroxylysine Amino acid found only in connective tissue pro-
teins (collagen and elastin); incorporated into the protein as
lysine and then hydroxylated in a vitamin C-dependent reaction;
abbr Hyl, M
r
162.2, pK
a
2.13, 8.62, 9.67.
hydroxyproline Amino acid found mainly in connective tissue
proteins (collagen and elastin); incorporated into the protein
as proline and then hydroxylated in a vitamin C-dependent
reaction; abbr Hyp, M
r
131.1, pK
a
1.82, 9.66. Peptides of
hydroxyproline are excreted in the urine and the output is
increased when collagen turnover is high, as in rapid growth or

resorption of tissue. Excretion is significantly lower than normal
in children whose growth is impaired by protein–energy mal-
nutrition. Measurement of hydroxyproline in meat products
245
permits determination of the connective tissue content of the
product
hydroxyproline index The ratio of urinary hydroxyproline: crea-
tinine/kg body weight; low in malnourished children.
5-hydroxytryptamine (5HT) Also called serotonin. A neuro-
transmitter amine synthesised from the amino acid tryptophan,
also formed in blood platelets; it acts as a vasoconstrictor. Found
in plantains and some other foods, but metabolised in the
intestinal mucosa by monoamine oxidase.
Hyfoama
TM
Hydrolysed milk and wheat protein used to prepare
stable foams for confectionery manufacture that, unlike egg
albumin foams, do not denature and cannot be overwhipped.
hygrometer Instrument for measuring humidity and/or water
activity. Also known as a psychrometer.
hygroscopic Readily absorbing water, as when table salt becomes
damp. Materials such as calcium chloride and silica gel absorb
water very readily and are used as drying agents. Hygroscopic
foods are those in which the partial pressure of water vapour
varies with the moisture content, so that they take up moisture
from the atmosphere.
Hy-Lite
TM
See bioluminescence.
hyoscine See atropine.

hyperalimentation Provision of unusually large amounts of
energy, either intravenously (parenteral nutrition) or by naso-
gastric tube or gastrostostomy tube (see enteral nutrition).
hyperammonaemia High blood ammonia concentration (normal
<80µmol/L), especially after protein intake, leading to coma,
convulsions and possibly death. May be due to a variety of
genetic diseases (see amino acid disorders) or liver failure.
Treatment is normally by severe restriction of protein intake.
hypercalcaemia Elevated plasma calcium believed to be due to
hypersensitivity of some children to vitamin d toxicity. There is
excessive absorption of calcium, with loss of appetite, vomiting,
constipation, flabby muscles and calcinosis, deposition of calcium
in the tissues. It can be fatal in infants.
hyperchlorhydria Excess secretion of hydrochloric acid in the
stomach due to secretion of a greater volume of gastric juice
(gastric secretion) rather than to a higher concentration.
hypercholesterolaemia Abnormally high concentrations of cho-
lesterol in the blood; normal total plasma cholesterol is below
5.2mmol/L; above 6.5mmol/L is considered abnormal and
indicative of the need for intervention. Generally considered to
be a sign of high risk for atherosclerosis and ischaemic heart
disease.Treatment is by restriction of fat (especially saturated
fat, see fat, saturated) and cholesterol intake and a high intake
246
of non-starch polysaccharides, which increase the excretion of
cholesterol and its metabolites (the bile salts) in the faeces.
In severe cases, drugs (hmg coa reductase inhibitors) may be
given to inhibit the synthesis of cholesterol in the body, or ion-
exchange resins may be fed, to increase the excretion of bile
salts. Familial hypercholesterolaemia is a genetic disease in

which affected individuals have extremely high blood concen-
trations of cholesterol, frequently dying from ischaemic heart
disease in early adulthood; treatment is as for other forms of
hypercholesterolaemia, but more rigorous.
See also lipoproteins, plasma.
hyperfiltration See osmosis, reverse.
hyperglycaemia High blood glucose (normal is 3.5–5.5mmol/L),
caused by a failure of the normal hormonal mechanisms of blood
glucose control.
See also diabetes; glucose tolerance; insulin.
hyperinsulinaemia (hyperinsulinism) Excessive secretion of
insulin, either as a result of an insulinoma, or due to hyper-
glycaemia resulting from insulin resistance.
hyperkalaemia Excessively high blood concentration of
potassium.
hyperkinetic syndrome (hyperkinesis) Mental disorder of chil-
dren, characterised by excessive activity and impaired attention
and learning ability. Has been attributed to adverse reactions
to food additives, but there is little evidence.
hyperlipidaemia (hyperlipoproteinaemia) A variety of condi-
tions in which there are increased concentrations of lipids in
plasma, phospholipids, triglycerides, free and esterified cho-
lesterol or free fatty acids.
See also hypercholesterolaemia; lipoproteins, plasma.
hyperoxaluria genetic disease leading to excessive formation of
oxalic acid, which causes the formation of kidney stones. Treat-
ment includes a diet low in those fruits and vegetables that are
sources of oxalic acid and in some cases supplements of vitamin
b
6

some 50–100 times greater than normal requirements.
hyperphosphataemia Excessively high blood concentration of
phosphate.
hypersalivation Excessive flow of saliva.
hypertension High blood pressure;a risk factor for ischaemic
heart disease, stroke and kidney disease.May be due to increased
sensitivity to salt (correctly, sensitivity to sodium), and treated
by restriction of salt intake, together with drugs; increased intake
of fruits and vegetables (as a safe source of potassium) is
recommended.
See also salt-free diets.
247
hyperthyroidism See thyrotoxicosis.
hypertonic A solution more concentrated than the body fluids;
see isotonic.
hypervitaminosis Overdosage with vitamins, leading to toxic
effects. A problem with high levels of intake of vitamins a, d, b
6
and niacin, normally at levels of intake from supplements con-
siderably higher than might be obtained from foods, although
hypervitaminosis A and D may result from (enriched) foods.
See also hormesis; hypercalcaemia; reference intakes; ul.
hypobaric storage Of fruits and vegetables, storage below atmos-
pheric pressure to enhance loss of CO
2
and ethylene, so slowing
ripening.
See also packaging, modified atmosphere.
hypocalcaemia Low blood calcium, leading to tetany (uncon-
trollable twitching of muscles) if severe; may be due to under-

activity of the parathyroid gland, kidney failure or vitamin d
deficiency.
hypochlorhydria Partial deficiency of hydrochloric acid secretion
in the gastric juice.
See also achlorhydria; anaemia, pernicious; gastric
secretion.
hypogeusia Diminished sense of taste. An early sign of marginal
zinc deficiency, and potentially useful as an index of zinc status.
See also dysgeusia; gustin; parageusia.
hypoglycaemia Abnormally low blood glucose; (normal is
3.5–5.5mmol/L); may result in loss of consciousness, hypogly-
caemic coma.
hypoglycaemic agents Three groups of compounds are used as
oral hypoglycaemic agents for treatment of non-insulin-
dependent diabetes mellitus: the sulphonylureas (chlor-
propamide, glibenclamide, glicazide, glimepiride, glipizide, gliq-
uidone, tolazamide, tolbutamide) act to enhance secretion of
insulin; buformin, metformin and phenformin are biguanides
that act to decrease gluconeogenesis and increase peripheral
utilisation of glucose; thiazolidinediones activate the PPAR
γ
receptor, so decreasing insulin resistance, modifying adipocyte
differentiation and decreasing leptin secretion.
hypokalaemia Abnormally low plasma potassium.
hypophosphataemia Abnormally low plasma phosphate.
hypoproteinaemia Abnormally low total plasma protein
concentration.
hyposite Little used word, from Greek, for low-energy food.
hypothermia Low body temperature (normal is around 37°C).
Occurs among elderly people far more readily than in younger

248
adults, often with fatal results. Also used in connection with
deliberate reduction of body temperature to 28°C to permit
heart and brain surgery.
hypothyroidism Underactivity of the thyroid gland, leading to
reduced secretion of thyroid hormones and a reduction in basal
metabolic rate. Commonly associated with goitre due to iodine
deficiency. In hypothyroid adults there is a characteristic moon-
faced appearance, lethargy and dull mental apathy. In infants,
hypothyroidism can lead to severe mental retardation, cretinism.
See also thyrotoxicosis.
hypotonic A solution more dilute than the body fluids, See
isotonic.
hypovitaminosis vitamin deficiency.
hypoxanthine A purine, an intermediate in the metabolism of
adenine and guanine to uric acid.
hyssop Pungent aromatic herb, Hyssopus officinalis, used in
salads, soups and in making liqueurs.
I
iatrogenic A condition caused by medical intervention or drug
treatment; iatrogenic nutrient deficiency is caused by drug–
nutrient interactions.
IBC Intermediate bulk container.
iberian moss See carrageenan.
ice cream A frozen confection made from fat, milk solids and
sugar. Some European countries permit the use of non-milk fat
and term the product ice cream, while if milk fat is used, it is
termed dairy ice cream. According to UK regulations, contains
not less than 5% fat and 7% other milk solids. In the USA the
minimum butterfat content is 10% with at least 20% total milk

solids. Reduced fat ice cream contains 25% less fat, and light ice
cream 50% less fat, or one-third less energy (and less than 50%
of energy from fat). Low-fat ice cream contains not more than
3g, and non-fat ice cream less than 0.5g milk fat per serving.
Stabilisers such as carboxymethylcellulose, gums and alginates
are included, and emulsifiers such as polysorbate and monoglyc-
erides. Mono- and diglycerides bind the looser globules of water
and are added in ‘non-drip’ ice cream.
ice, eutectic See eutectic ice.
Iceland moss A lichen, Cetraria islandica, that can be boiled to
make a jelly.
ichthyosarcotoxins Toxins in fish.
IDDM Insulin-dependent diabetes mellitus.
249