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incretins Hormones that increase the amount of insulin secreted in response to glucose, reduce glucagon secretion and delay gastric emptying.. They may also have actions to improve insul

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

3 g, and non-fat ice cream less than 0.5 g 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

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idi Indian, Sri Lankan; steamed bread made from rice and legume flour The dough is left to undergo bacterial fermentation

overnight; the main organisms are Leuconostoc mesenteroides and Streptococcus faecalis.

idiopathic A condition of unknown origin or cause

idiosyncrasy Unusual and unexpected sensitivity or reaction to a drug or food

IDL Intermediate-density lipoprotein; see lipoproteins, plasma.

idli S.E Asian; small cakes made from a mixture of cooked rice and black gram, fermented with the aid of mould

IHD Ischaemic heart disease

ileitis Inflammation of the ileum

ileocolitis Inflammation of the ileum and colon

ileostomy Surgical formation of an opening of the ileum on the

abdominal wall, performed to treat severe ulcerative colitis; see

gastrointestinal tract

ileotomy Surgical removal of (part of) the ileum

ileum Last portion of the small intestine, between the jejunum

and the colon (large intestine), see gastrointestinal tract.

ileus Obstruction of the intestines, see gastrointestinal tract.

illipe butter See cocoa butter equivalents.

IMF See intermediate moisture foods.

immune system Series of defence mechanisms of the body There are two major parts: humoral, mediated through antibodies secreted into the circulation (immunoglobulins); and cell-mediated Lymphocytes produce antibodies against, and bind to, the antigens of foreign cells, leading to death of the invading organisms; other white blood cells are phagocytic and engulf the invading organisms

immunoassay A variety of analytical techniques with very high specificity and sensitivity using antibodies raised against the analyte, coupled with an enzyme, fluorescent dye or radioactive material as a detection system

See also elisa; fluorescence immunoassay;

radioimmunoas-say

immunoglobulins Specific antibodies produced in the blood in response to foreign proteins or other antigens Five classes, IgA, IgE, IgG, IgM and IgI; present in circulating blood as a result of previous exposure to the antigens, and also present in breast milk

to confer passive immunity

immunomagnetic separation Technique for rapid isolation of food-borne pathogens using magnetic microspheres coated with antibodies

IMP (1) See integrating motor pneumotachograph.

(2) Inosine monophosphate, one of the purine nucleotides 250

impingement drying Hot air is blown against the surface of the food through nozzles; used mainly to remove surface moisture from thin sheets of food

improvers, flour See ageing.

IMS See immunomagnetic separation.

inanition Exhaustion and wasting due to complete lack or non-assimilation of food; a state of starvation

inborn errors of metabolism See genetic disease.

incaparina A number of protein-rich dietary supplements devel-oped by the Institute of Nutrition of Central America and Panama (INCAP), based on cottonseed flour, or soya and vegetables, with various nutrient supplements, containing 27.5% protein

incidence rate Measure of morbidity based on the number of new episodes of a disease arising in a population over a given period

of time

See also prevalence rate.

incretins Hormones that increase the amount of insulin secreted

in response to glucose, reduce glucagon secretion and delay gastric emptying They may also have actions to improve insulin sensitivity, and they may increase the formation of pancreatic β-islet cells

See also gip; glp-1; orexins.

index of nutritional quality (INQ) An attempt to provide an overall figure for the nutrient content of a food or diet The ratio

of the amount of the nutrient/1000 kcal : the reference intake/

1000 kcal

Indian corn See maize.

Indian fig See prickly pear.

Indian gum Ghatti gum, polysaccharide exudate from the stems

of Anogeissus latifolia.

Indian rice grass Perennial, growing wild in the USA, Oryzopsis hymenoides; tolerant to drought The seeds resemble millet,

small, round, dark in colour, covered with white hairs Tradition-ally used by native Americans for flour, now almost exclusively for forage

indigestion Discomfort and distension of the stomach after a meal, also known as dyspepsia, including heartburn Persistent indigestion may be a symptom of a digestive disorder such as hiatus hernia or peptic ulcer

indigo carmine Blue food colour (E-132), derivative of indigotin,

which comes from tropical leguminous plants Indigofera spp.

induction Of enzymes; an increase in the total amount of the enzyme protein in a cell as a result of increased transcription

of DNA, leading to an increased amount of mRNA

See also repression.

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induction period The lag period during which a fat or oil shows stability to oxidation because of its content of natural or added antioxidants, which are oxidised preferentially After this there

is a sudden and large consumption of oxygen and the fat becomes rancid

infarction Death of an area of tissue because its blood supply has been stopped

INFOODS International Network of Food Data Systems, created

to develop standards and guidelines for collection of food com-position data, and standardised terminology and nomenclature

Web site http://www.fao.org/infood/.

infuse (infusion) To extract the flavour from herbs, spices, etc., by steeping them in a liquid, usually by pouring on boiling liquid, covering and leaving to stand without further cooking, as in making tea

injera Ethiopean; flat bread made from teff flour fermented for 30–72 hours with a starter from a previous batch; the main

organism is the yeast Candida guilliermondii.

inorganic Materials of mineral, as distinct from animal or veg-etable, origin Apart from carbonates and cyanides, inorganic chemicals are those that contain no carbon

inositol A carbohydrate derivative which is an essential nutrient for micro-organisms and many animals and sometimes classified

as a vitamin, although there is no evidence that it is a dietary essential for human beings Deficiency causes alopecia in mice and ‘spectacle eye’ (denudation around the eye) in rats Obsolete names inosite and meat sugar

Chemically, hexahydrocyclohexane (CHOH)6; there are nine

isomers, but only one, meso- or myo-inositol, is of physiological

importance It is a constituent of many phospholipids (phos-phatidyl inositols) involved in membrane structure and as part

of the signalling mechanism for hormones which act at the cell surface The insecticide gammexane is hexachlorocyclohexane, and appears to function by competing with inositol Inositol hexaphosphate is phytic acid

INQ See index of nutritional quality.

in silico Experiments conducted by computer simulation, by analogy with IN VITROand IN VIVO

instant foods Dried foods that reconstitute rapidly when water is added, e.g tea, coffee, milk, soups, precooked cereal products, potatoes The dried powders may be agglomerated to control particle size and improve solubility ‘Instant puddings’ are for-mulated with pregelatinised starch and disperse rapidly in cold milk

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insulin Peptide hormone secreted by the β-islet cells of the pan-creas; controls glucose metabolism diabetes mellitus is the result of inadequate supply of insulin or tissue resistance to its action Since insulin is a protein it would be digested if taken by mouth so must be injected Originally the hormone was prepared from beef or pork pancreas, but these differ slightly in structure from human insulin, and lead to antibody formation after pro-longed use Most insulin for therapeutic use is now human insulin, the product of biosynthesis from the human insulin gene

See also diabetes; glucose tolerance; hypoglycaemic agents;

metabolic syndrome

insulinaemic index The rise in blood insulin elicited by a test dose (usually 50 g) of a carbohydrate food compared with that after

an equivalent dose of glucose

See also glycaemic index.

insulin-like growth factors See somatomedins.

insulinoma insulin-secreting tumour of the β-islet cells of the pancreas

insulin resistance Resistance of target tissues to the actions of insulin, leading to hyperinsulinaemia and hyperglycaemia, commonly associated with abdominal adipose tissue Only the metabolic actions of insulin are affected; the slower actions medi-ated via map kinases are unaffected, so there is an exaggermedi-ated mitotic response to insulin, causing increased proliferation

of vascular smooth muscle, leading to atherosclerosis and hypertension

See also metabolic syndrome.

integrating motor pneumotachograph (IMP) Apparatus for mea-suring energy expenditure indirectly from oxygen consumption

It meters the expired air and removes a proportion for analysis

See also spirometer.

intense sweeteners See sweeteners, intense.

interesterification Exchange of fatty acids between triacyl-glycerols in order to modify the properties of the fat; may be achieved by heat treatment or using fungal lipase

interferon A family of proteins that are secreted by macrophages (IFN-α), fibroblasts (IFN-β) and lymphocytes (IFN-γ) in response to viral, bacterial or lectin stimulation They have potent antiviral activity, acting by inhibiting translation of viral RNA, and inhibit proliferation of cancer cells

interleukins A family of cytokines that act as signalling mole-cules between leukocytes

intermediate moisture foods These are semimoist with about 25% (15–50%) moisture but with some of the water bound (and

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so unavailable to micro-organisms) by the addition of glycerol, sorbitol, salt or certain organic acids, so preventing the growth

of micro-organisms

international units (IU) Used as a measure of the potency or biological activity of substances such as vitamins and hormones, before chemical measurement was possible Still sometimes used (3.33 IU vitamin a= 1µg; 40IU vitamin d = 1µg; 1IU vitamin

e= 1mg)

intervention study Comparison of an outcome (e.g morbidity or mortality) between two groups of people deliberately subjected

to different dietary, drug or other regimes

intestinal flora Bacteria and other micro-organisms that are nor-mally present in the gastrointestinal tract

intestinal juice Also called succus entericus Digestive juice secreted by the intestinal glands lining the small intestine It contains a variety of enzymes, including enteropeptidase, the enzyme that converts trypsinogen to active trypsin, aminopepti-dase, nucleases and nucleotidases

See also gastrointestinal tract.

intestine The gastrointestinal tract; the small intestine (duodenum, jejunum and ileum) where the greater part of digestion and absorption take place, and the large intestine

intolerance (to foods) See adverse reactions to foods.

intravenous nutrition See parenteral nutrition.

intrinsic factor A protein secreted in the gastric juice by the pari-etal (oxyntic) cells of the gastric mucosa; essential for the absorp-tion of vitamin b12; impaired secretion results in pernicious anaemia

See also achlorhydria; dump suppression test; schilling

test

intron A region of dna within a gene that does not contain information coding for the protein and is spliced out during the post-transcriptional modification of mRNA

See also exon.

intussusception Telescoping or invagination of one part of the bowel into another

inulin Soluble undigested polymer of fructose found in root vegetables, especially Jerusalem artichoke Included with non-starch polysaccharides (dietary fibre) Also called dahlin and alant starch Filtered by the kidney and not reabsorbed, so used clinically to measure glomerular filtration rate and kidney function

inversion Applied to sucrose, meaning its hydrolysis to glucose

and fructose (see sugar, invert).

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invertase Also known as sucrase or saccharase; either of two enzymes, glucohydrolase (EC 3.2.1.20) or fructohydrolase (EC 3.2.1.26), with differing specificity, that hydrolyse sucrose to yield glucose and fructose Used in the manufacture of invert

sugar (see sugar, invert) and in chocolate confectionery to

hydrolyse crystalline sucrose to a liquid syrup The bifunctional sucrase–isomaltase of the intestinal mucosa is glucohydrolase

invert sugar See sugar, invert.

in vitro Literally ‘in glass’; used to indicate an observation made experimentally in the test tube, as distinct from the natural living conditions,IN VIVO.

in vivo In the living state, as distinct from IN VITRO

iodine An essential mineral, a trace element; reference intakes are about 140µg per day Iodine is required for synthesis of the thyroid hormones, which are iodotyrosine derivatives A prolonged deficiency of iodine in the diet leads to goitre It is plentifully supplied by sea foods and by vegetables grown in soil containing iodide In areas where the soil is deficient in iodide, locally grown vegetables are iodine deficient, and hence goitre occurs in defined geographical regions, especially inland upland areas over limestone soil Where deficiency is a problem, salt may

be iodised (see iodised salt) to increase iodide intake.

iodine number (iodine value) Measurement of the degree of unsaturation of fatty acids by iodination of the carbon–carbon double bonds The Wijs method uses iodine chloride, Hanus iodine bromide, and Rosenmund–Kuhnhenn a pyridine sul-phate/bromine reagent

iodine, protein-bound The thyroid hormones, tri-iodothyronine and thyroxine, are transported in the bloodstream bound to pro-teins; measurement of protein-bound iodine, as opposed to total plasma iodine, was used as an index of thyroid gland activity before more specific methods of measuring the hormones were developed

iodised oil Oil intended for administration either by injection or orally in regions of severe iodine deficiency; prepared by treat-ing vegetable oils with iodine, which adds across double bonds Oils used include poppyseed, peanut and rape seed oils; injec-tions provide protection for 2–4 years, oral administration about

1 year

iodised salt In areas of mild iodine deficiency, salt is often enriched with iodate at levels of 10–25 mg iodate/kg; in areas of moderate deficiency to levels of 25–40 mg/kg Where there is severe deficiency, iodised oil is used In some areas all salt is enriched, in others it is optional In some countries bread must

be made with iodised salt

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iodopsin See rhodopsin.

IoM Institute of Medicine of the US National Academies; web site http://www.iom.edu/

ion An atom or molecule that has lost or gained one or more elec-trons, and thus has an electric charge Positively charged ions are known as cations, because they migrate towards the cathode (negative pole) in solution, while negatively charged ions migrate towards the positive pole (anode) and hence are known as anions

ion-exchange resin An organic compound that will adsorb ions under some conditions and release them under other conditions The best-known example is in water softening, where calcium ions are removed from the water by binding to the resin, dis-placing sodium ions The resin is then regenerated by washing with a concentrated solution of salt, when the sodium ions displace the calcium ions Ion-exchange resins are used for purification of chemicals, metal recovery, a variety of analytical techniques and treatment of hypercholesterolaemia

ionisation The process whereby the positive and negative ions of

a salt or other compound separate when dissolved in water The degree of ionisation of an acid or alkali determines its strength

(see ph).

ionising radiation See irradiation.

IQB (individual quick blanch) Steam blanching method in which all particles receive the same heat treatment, unlike con-ventional steam blanching where particles at the periphery of the bed are overheated when those in the centre are adequately treated

IQF Individual quick frozen or freezing

Irish moss A red seaweed, Chondrus crispus; source of the

polysaccharide carrageenan

Composition/100 g: water 81 g, 205 kJ (49 kcal), protein 1.5 g, fat 0.2 g, carbohydrate 12.3 g (0.6 g sugars), fibre 1.3 g, ash 4.7 g, Ca

72 mg, Fe 8.9 mg, Mg 144 mg, P 157 mg, K 63 mg, Na 67 mg, Zn

2 mg, Cu 0.1 mg, Mn 0.4 mg, Se 0.7µg, vitamin A 6µg RE (71µg carotenoids), E 0.9 mg, K 66.9 mg, B10.01 mg, B20.47 mg, niacin 0.6 mg, B60.07 mg, folate 182µg, pantothenate 0.2mg, C 3mg

iron An essential mineral The average adult has 4–5 g of iron, of which 60–70% is present in the blood as haem in the circulating haemoglobin, and the remainder present in myoglobin in muscles, a variety of enzymes and tissue stores Iron is stored in the liver in ferritin, in other tissues in haemosiderin, and in the blood transport protein transferrin

Iron balance: losses in faeces 0.3–0.5 mg per day, in sweat and skin cells 0.5 mg, traces in hair and urine, total loss 0.5–1.5 mg per 256

day Blood loss leads to a considerable loss of iron The average diet contains 10–15 mg, of which 0.5–1.5 mg is absorbed The haem iron of meat and fish is considerably better absorbed than the inorganic iron of vegetable foods Absorption of iron

is enhanced by vitamin c taken at the same time as iron-containing foods, and reduced by phosphate, calcium and phytic acid

See also anaemia; ferritin; haemochromatosis; iron storage;

transferrin

iron ammonium citrate See ferric ammonium citrate.

iron binding capacity, total See transferrin.

iron chink Machine designed in 1903 by US inventor A K Smith

to behead, split and gut salmon in a continuous operation; so-called because it replaced Chinese labour in canneries

iron ration Heat-resistant high-energy chocolate ration enriched with vitamins and minerals devised for US Army by Capt Paul Logan and first produced by Hershey Chocolate in 1937, as the Logan Bar Ration D (for daily) Heat-resistant because it did not contain cocoa butter

iron, reduced Metallic iron in finely divided form, produced by reduction of iron oxide The form in which iron is sometimes added to foods, such as bread Also known by its Latin name

ferrum redactum.

iron storage ferritin is the iron storage protein in the intestinal mucosa, liver, spleen and bone marrow It is a ferric hydroxide– phosphate–protein complex containing 23% iron Haemosiderin

is a long-term reserve of iron in tissues; colloidal iron hydroxide combined with protein and phosphate, probably formed by agglomeration of ferritin, the short-term storage form Abnor-mally high levels of haemosiderin occur in siderosis

irradiation ionising radiation (X-rays or γ-rays) kills micro-organisms and insects, so is used for sterilisation of foods; also inhibits sprouting of potatoes

See also microwave cooking; radappertisation; radicidation;

radurisation; ultraviolet radiation

IRRI International Rice Research Institute, Los Baños, Philip-pines Web site http://www.irri.org/

irritable bowel syndrome Also known as spastic colon or mucous colitis Abnormally increased motility of the large and small intestines, leading to pain and alternating diarrhoea and consti-pation; often precipitated by emotional stress

isaño Edible tubers of the Andean plant Tropaeolum tuberosum.

ischaemia Inadequate blood supply to a tissue

ischaemic heart disease Or coronary heart disease Group of syn-dromes arising from failure of the coronary arteries to supply

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sufficient blood to heart muscles; associated with atherosclero-sis of coronary arteries

isinglass gelatine prepared from the swim bladder of fish (espe-cially sturgeon) Used commer(espe-cially to clear wine and beer, and sometimes in jellies and ice cream Japanese isinglass is agar

islets of Langerhans The endocrine parts of the pancreas; glucagon is secreted by the α-cells, insulin by the β-cells and gastrin by the γ-cells of the islets

ISO 9000 Quality Standard The international standard for the management of quality, widely used in the food industry, cater-ing and food distribution, but developed originally for the engi-neering industry ISO 9001 covers the specification for design, manufacture and installation; ISO 9002 the specification for man-ufacture and installation; ISO 9003 the specification for final inspection and test

isoacids Obsolete term for isomers of unsaturated fatty acids

(including trans-isomers) formed during hydrogenation of oils.

isoamylase See debranching enzymes.

isoascorbic acid See erythorbic acid.

isobaric Processes in which the pressure is held constant and volume varies with temperature

See also adiabatic; isothermal.

isodesmosine See desmosine.

isoelectric focusing (electrofocusing) A technique for separating proteins, etc., by electrophoresis on a support medium that pro-vides a pH gradient, so that each comes to rest at a position determined by its isoelectric point

isoelectric point The pH at which an ionised molecule (e.g a protein or amino acid) has no net charge

isoenzymes Enzymes that have the same catalytic activity, but different structures, properties and/or tissue distribution

isoflavones See flavonoids.

isohumulones See humulones.

isoleucine An essential amino acid, abbr Ile (I), Mr 131.2, pKa

2.32, 9.76, codons AUA, AUPu Rarely limiting in food It is one

of the branched-chain amino acids, together with leucine and valine

isomalt A bulk sweetener, about half as sweet as sucrose, con-sisting of a mixture of two disaccharide polyols, glucosorbitol and glucomannitol About 50% metabolised, yielding 9 kJ (2.4 kcal)/gram.Thought to be less laxative than sorbitol or man-nitol, and does not encourage tooth decay, so is used in tooth-friendly sweets It absorbs very little water, so products are less sticky than those made with sucrose and have a longer shelf-life

isomalto-oligosaccharides See oligosaccharides.

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