L

lac A red colourant (a complex mixture of anthraquinones) obtained from the insect Laccifera lacca (Coccus lacca) found on the trees Schleichera oleosa, Ziziphus mauritiana and Butea monosperma, which grow in India and Malaysia. The lac insects are also the source of shellac. laccase See phenol oxidases.

lacquer With reference to canned foods (see canning), a layer of synthetic resin is coated onto the tinplate and hardened with heat. The layer of lacquer protects the tin lining from attack by acid fruit juices.

lactalbumin One of the proteins of milk. Unlike casein, not precipitated from acid solution; hence, during cheese-making the whey contains lactalbumin and lactoglobulin. They are precipitated by heat and a whey cheese can be made in this way. lactase The enzyme (P-galactosidase, EC 3.2.1.23) that hydrolyses lactose to glucose and galactose; present in the brush border of the intestinal mucosal cells. Deficiency of lactase (alactasia) is common in most ethnic groups after adolescence, leading to lactose intolerance. Fungal lactase is used to produce lactose-free milk for people suffering from alactasia.

See also disaccharide intolerance. lactic acid The acid produced by the anaerobic metabolism of glucose. Originally discovered in sour milk, it is responsible for the flavour of fermented milk and for the precipitation of the casein curd in cottage cheese. Also produced by fermentation in silage, pickling, sauerkraut, cocoa, tobacco; its value here is in suppressing the growth of unwanted organisms.

It is formed in mammalian muscle under conditions of maximum exertion (see glucose metabolism) and by metabolism of glycogen in meat immediately after death of the animal. Lactic acid in muscle was at one time known as sarcolactic acid.

Used as an acidulant in sugar confectionery, soft drinks, pickles and sauces. (E-270; salts of lactic acid are E-325-327.) lactic acid, buffered A mixture of lactic acid and sodium lactate used in sugar confectionery to provide an acid taste without inversion of the sugar, which occurs at lower pH. lactitol sugar alcohol derived from lactulose. Not digested by digestive enzymes but fermented by intestinal bacteria to short-chain fatty acids, some of which are absorbed; it yields about 8kJ (2kcal)/g and hence has a potential use as a low-calorie bulk sweetener; also retards crystallisation and improves moisture retention in foods (E-966). Because of bacterial fermentation in the colon, it is also used as an osmotic laxative. Also known as lactit, lactositol, lactobiosit. Lactobacillus Genus of bacteria capable of growth in acidic medium, and producing lactic acid by fermentation of carbohydrates. Responsible for souring of milk, and production of flavour in yogurt and other fermented milk products.

See also probiotics. Lactobacillus casei factor Obsolete name for folic acid. lactobiose See lactose. lactobiosit See lactitol.

lactochrome Obsolete name for riboflavin (vitamin b2). lactoferrin Iron-protein complex in human milk (only a trace in cow's milk), only partly saturated with iron; has a role inhibiting the growth of E. coli and other potentially pathogenic organisms. lactoflavin Obsolete name for riboflavin (vitamin b2), so named because it was isolated from milk. lactogen A drug or other substance that increases the production and secretion of milk. Lactogenic hormone is prolactin. lactoglobulin See lactalbumin.

lactometer Floating device used to measure the specific gravity of milk (1.027-1.035). Lac-toneTM Protein-rich baby food (26% protein) made in India from peanut flour, skim milk powder, wheat flour and barley flour with added vitamins and calcium. lacto-ovo-vegetarian One whose diet excludes animal foods (i.e. flesh) but permits milk and eggs.

lactose Milk sugar, the carbohydrate of milk; a disaccharide, P-1,4-glucosyl-galactose. Used pharmaceutically as a tablet filler and as a medium for growth of micro-organisms. The fermentation of lactose to lactic acid by bacteria is responsible for the souring of milk. Ordinary lactose is a-lactose, which is 16% as sweet as sucrose; if crystallised above 93 °C, it is isomerised to the P-form which is more soluble and sweeter.

See also disaccharide intolerance; lactase. lacto-serum See whey. lactositol See lactitol. lactostearin See glyceryl lactostearate. lactosucrose A trisaccharide (galactosyl-glucosyl-fructose) formed from sucrose and lactose by fructosyl transfer catalysed by invertase (EC 3.2.1.6). Considered to be a prebiotic. lactulose A disaccharide, P-1,4-fructosyl-galactose, which does not occur naturally but is formed in heated or stored milk by isomerisation of lactose. About half as sweet as sucrose. Not hydrolysed by human digestive enzymes but fermented by intestinal bacteria to form lactic acid and pyruvic AciD.Thought to promote the growth of Lactobacillus bifidus and so added to some infant formulae. Because of bacterial fermentation in the colon it is an osmotic laxative. ladies' fingers See okra; also a short kind of banana. laetrile See amygdalin. laevorotatory See optical activity. laevulose See fructose.

lafun West and East African; flour made from yam, cassava or plantain that has been soaked in water and allowed to undergo lactic acid bacterial fermentation for 2-5 days, then sun-dried and pounded into flour. lamb Meat from sheep (Ovis aries) younger than 12-14 months.

Composition/100g (varying according to joint): (edible portion 79%) water 61-64g, 960-1100kJ (230-260kcal), protein 17-18g, fat 17-21 g (of which 47% saturated, 44% mono-unsaturated, 9% polyunsaturated), cholesterol 70mg, ash 0.9g, Ca 9-16mg, Fe 1.5-1.7mg, Mg 21-23mg, P 160-170mg, K 230-250mg, Na 60mg, Zn 3-4mg, Cu 0.1 mg, Se 20 |g, vitamin E 0.2mg, B1 0.1 mg, B2 0.2mg, niacin 6mg, B6 0.14mg, folate 19|g, B12 2.5 |g, pantothenate 0.7mg. A 100g serving is a source of Fe, vitamin B2, pantothenate, a good source of P, Se, Zn, a rich source of niacin, vitamin B12. lamb's lettuce Or corn salad. Hardy annual plant, Valerianella locusta or V. olitoria, traditionally used in salads in winter and early spring.

lamb's wool Old English drink made by pouring hot ale over pulped roasted apples and adding sugar and spices. laminarin A non-starch polysaccharide from kelp (Laminaria spp.); a short polymer of glucose linked P(1-3) with P(1-6) branch points.

lamination Bonding together of two or more packaging films, papers or foods.

lamprey (lampern) Cartilaginous fish resembling eel; sea lamprey is Petromyzon marinus, river lamprey or lampern is Lampetra fluviatilis.

Lancashire English hard cheese with a crumbly texture. landrace Variety of plant or animal, highly adapted to local conditions, often associated with traditional agriculture. LanepaTM Capsules of fish oil rich in m3 polyunsaturated fatty acids.

langouste shellfish, Palinurus vulgaris; see lobster. lanolin The fat from wool. Consists of a mixture of cholesterol oleate, palmitate and stearate, not useful as food; used in various cosmetics. lansoprazole See proton pump.

lao-chao South-east Asian; sweet slightly alcoholic glutinous rice. Boiled rice is inoculated with a starter (ragi), which introduces various amylase-producing moulds, including Rhizopus spp., and fermented for 2-3 days. larch gum A polysaccharide of galactose and arabinose (ratio 1:6), found in the aqueous extract of the Western larch tree (Larix occidentals); a potential substitute for gum arabic, since it is readily dispersed in water. lard Originally rendered fat from pig carcass (sheep and cattle also used). The best quality is from the fat surrounding the kidneys; neutral lard is the highest quality, prepared by agitating the minced fat with water at a temperature below 50 °C; kidney fat provides No. 1 quality; back fat provides No. 2 quality. Leaf lard is made from the residue of kidney and back fat after the preparation of neutral lard by heating with water above 100°C in an autoclave. Prime steam lard is fat from any part of the carcass, rendered in the autoclave. Fatty acids 41% saturated, 47% mono-unsaturated, 12% polyunsaturated. Lard used to be stored in pig's bladder, hence the expression 'bladder of lard' for a grossly obese person.

See also lard compounds; lard substitutes. lard compounds Blends of animal fats, such as oleostearin or premier jus, with vegetable oils, to produce products similar to lard in consistency and texture.

See also lard substitutes.

lardine See margarine.

lard substitutes Vegetable shortenings made from mixtures of partially hardened vegetable fats with the consistency of lard.

See also lard compounds. lardy cake West of England; made from bread dough, lard, sugar and dried fruit.

lasagne Wide ribbons of pasta; lasagne verdi is flavoured with spinach. Narrow ribbons are lasagnette. lathyrism The effect of consuming Lathyrus spp. peas (chickling vetch, flat-podded vetch, Spanish vetchling, Indian vetch), which contain the neurotoxin oxalyl-diaminopropionic acid. Although growing Lathyrus spp. has been banned in many countries, lath-yrism continues to be a public health problem in India since kesari dhal, Lathyrus sativa, is a hardy crop that survives adverse conditions and can become a large part of the diet in times of drought.

See also odoratism. lauric acid A medium-chain length saturated fatty acid (C12:0)

in butter, coconut oil and palm oil. lauter tun Vertical cylindrical tank for extracting and clarifying wort and separating it from spent grain in malting and brewing. Laval separator Centrifuge for separating cream from milk, invented by Swedish engineer Carl Gustaf Patrik de Laval, 1877.

laver Edible seaweed, Porphyra spp. Laver bread is made by boiling in salted water and mincing to a gelatinous mass. It is made into a cake with oatmeal or fried. Locally known in S. Wales as bara lawr.

Composition/100 g: water 85 g, 147 kJ (35 kcal), protein 5.8 g, fat 0.3g, carbohydrate 5.1g (0.5g sugars), fibre 0.3g, ash 3.8g, Ca 70 mg, Fe 1.8 mg, Mg 2mg, P 58mg, K 356mg, Na 48mg, Zn 1 mg, Cu 0.3 mg, Mn 1mg, Se 0.7 |jg, vitamin A 260 |jg RE (3121 |ig carotenoids), E 1mg, K 4mg, B1 0.1mg, B2 0.45mg, niacin 1.5 mg, B6 0.16mg, folate 146|j.g, pantothenate 0.5 mg, C 39mg. lax Scandinavian name for salmon.

See also gravadlax; lox. laxarinic acid See maltol.

laxatives Compounds used to treat constipation. Bulk-forming laxatives include various preparations of non-starch polysaccharide.

Stimulant or contact laxatives include senna and cascara (Rhamnus purshianus, Frangula purshiana) in which the active ingredients are anthroquinones, aloe vera extract, bisacodyl (a diphenylmethene derivative), phenolphthalein and sodium picosulphate.

Osmotic laxatives include magnesium salts (epsom salts), lactitol and lactulose.

Emollient laxatives (faecal softeners) include liquid paraffin and docusates (which act as detergents to permit penetration of water into the faecal mass).

A number of drugs are used to increase intestinal motility. lazybed Narrow strip of land, about 500-800 m in length, used traditionally in the Andes for growing potatoes, and adopted in Ireland about 1640; one lazybed will provide enough potatoes for a family for a year. LC-MS Liquid chromatography linked to a mass spectrometer as the detection system. LD50 An index of acute toxicity (lethal dose 50%); the amount of the substance that kills 50% of the test population of experimental animals when administered as a single dose. LDL Low-density lipoprotein, see lipoproteins, plasma. leaching The process of extracting soluble compounds from a food with water or another solvent; may be deliberate (as, e.g., in water extraction of sugar from beet, or solvent extraction of oil from oilseeds), or accidental, when vitamins and minerals leach into cooking water and are lost. lead A mineral of no nutritional interest, since it is not known to have any function in the body. It is toxic and its effects are cumulative. May be present in food from traces naturally present in the soil, as contamination of vegetables grown near main roads, which absorb volatile lead compounds formerly used as a petrol additive, from shellfish that have absorbed it from seawater, from lead glazes on cooking vessels and in drinking water where lead pipes are used. Traces are excreted in the urine. lean body mass Measure of body composition excluding adipose tissue, i.e. cells, extracellular fluid and skeleton. Lean CuisineTM A range of frozen meals prepared to a specified energy content.

leathers, fruit Fruit purées dried in air in thin layers, 4-5 mm thick, then built up into thicker preparations. leaven yeast, or a piece of dough kept to ferment the next batch. leavening Baked goods may be leavened mechanically by air incorporated in dough mixing, or steam produced in baking; chemically using a baking powder (sodium, potassium or ammonium bicarbonate together with an acid); or biologically by yeast fermentation. leben See milk, fermented.

LecigranTM soya bean lecithin preparation, claimed to lower blood cholesterol.

lecithin Chemically lecithin is phosphatidyl choline; a phospholipid containing choline. Commercial lecithin, prepared from soya bean, peanut and maize, is a mixture of phospholipids in which phosphatidyl choline predominates.

Used in food processing as an emulsifier, e.g. in salad dressing, processed cheese and chocolate, and as an antispattering agent in frying oils. Is plentiful in the diet and not a dietary essential.

lecithinase Any of a number of phospholipases that hydrolyse lecithin.

lectin One of a series of proteins found especially in legume seeds that are mitogenic, stimulating cell division, and also act to agglutinate cells (especially red blood cells, hence the old names haemagglutinin and phytoagglutinin). Lectins may be a cause of serious non-bacterial food poisoning, after consumption of raw or undercooked beans of some varieties of Phaseolus vulgaris (red kidney beans) causing vomiting and diarrhoea within 2 h, and severe damage to the intestinal mucosa; they are denatured, and hence inactivated, only by boiling for about 10min.

leek Allium ampeloprasum; a member of the onion family which has been known as a food for over 4000 years. The lower part is usually blanched by planting in trenches or earthing up, and eaten along with the upper long green leaves.

Composition/100g: (edible portion 44%) water 83g, 255kJ (61 kcal), protein 1.5 g, fat 0.3 g, carbohydrate 14.1 g (3.9g sugars), fibre 1.8 g, ash 1g, Ca 59 mg, Fe 2.1 mg, Mg 28 mg, P 35 mg, K 180mg, Na 20mg, Zn 0.1 mg, Cu 0.1 mg, Mn 0.5mg, Se 1 |g, vitamin A 83 |g RE (2900 |g carotenoids), E 0.9 mg, K 47 mg, B1 0.06mg, B2 0.03mg, niacin 0.4mg, B6 0.23mg, folate 64|g, pantothenate 0.1mg, C 12mg. An 80g serving is a source of Fe, Mn, vitamin C, a good source of folate. leghaemoglobin Haem-containing protein in the root nodules of leguminous plants that binds O2 for transport within the root, and so permits the growth of obligate anaerobic nitrogen-fixing micro-organisms, Rhizobium spp.

See also nitrogenase. legumes Food seeds of members of the leguminosae family. Consumed in the immature green state in the pod or as the dried mature seed (grain legumes and pulses) after boiling; a 100 g cooked portion contains approximately 50g of the dried product.

Include ground nut, Arachis hypogea, and soya bean, Glycine max, and African yam bean, Sphenostylis stenocarpa, grown for their edible tubers as well as seeds.

Phaseolus vulgaris Navy, Boston, pinto, string, snapbean (USA); haricot, kidney and when unripe, French, wax bean (UK); flageolet (yellow variety).

P. coccineus (P. multiflora) runner, scarlet runner, multiflora bean.

P. acutifolius (var. latifolius) tepary, rice haricot bean, Texan bean (USA).

P. lunatus (lumensis, inamoensus) Lima bean (USA), butter, Madagascar butter, Rangoon, Burma, Sieva bean.

Cajanus cajan (C. indicus) pigeon,Angola, non-eye pea, Congo bean or pea, red gram, yellow dhal.

Vigna umbellata (P. calcaratus) rice bean, red bean (also used for adzuki bean). Vigna mango (P. mungo) urd bean, black gram, mash. V. or P. angularis adzuki bean.

Vigna unguiculata (or V. sesquipedalis or sinensis, systematics confused) cow pea, black-eyed bean or pea, China pea, cowgram, catjang, southern pea. Vigna unguiculata sesquipedalis (L) asparagus bean, pea bean, yard-long bean.

V. aconitifolia (P. aconitifolia) moth, mat bean, Turkish gram. V. radiata (P. aureus, P. radiatus) mung bean, green or golden gram. Lablab purpureus (Dolichos lablab) bonavista, dolichos, Egyptian kidney, Indian butter, lablab, tonga, hyacinth bean.

Canavalia ensiformis jack, overlook, sword bean. Lens culi-naris (esculenta) lentil, red dhal, masur dhal, split pea.

Pisum sativa garden, green pea. Pisum aevense field pea. Voandzeia subterranea bambar(r)a groundnut, earth pea, ground bean, Kaffir pea, Madagascar groundnut.

Cicer aretinum chickpea, Bengal gram.

Cyamopsis tetragonoloba cluster bean. Lathyrus sativus grass, lathyrus, chickling pea, Indian vetch, khesari dhal. Macrotyloma uniflorum (Dolichos uniflorus) horse gram, horse grain, kulthi bean, Madras gram. Macuna pruriens velvet bean. Psophocarpus tetragonolobus winged bean, asparagus bean or pea, four-cornered, Goa, Manila, Mauritius bean. Vicia faba broad bean, faba, field, horse, pigeon, trick, windsor bean. legumin Globulin protein in legumes. Leicester English hard cheese coloured with annatto. lemon Sour fruit of Citrus limon.

Composition/100g: (edible portion 53%) water 89g, 121 kJ (29 kcal), protein 1.1 g, fat 0.3 g, carbohydrate 9.3 g (2.5g sugars), fibre 2.8 g, ash 0.3g, Ca 26mg, Fe 0.6mg, Mg 8mg, P 16mg, K 138mg, Na 2mg, Zn 0.1mg, Se 0.4|g, vitamin A 1 |g RE (35|g carotenoids), E 0.2mg, B1 0.04mg, B2 0.02mg, niacin 0.1 mg, B6 0.08 mg, folate 11 |g, pantothenate 0.2 mg, C 53 mg. An 80 g serving is a rich source of vitamin C.

lemon grass Herb, Cymbopogon spp., with lemon flavour, used in

South-east Asian cuisine; dried leaves are sereh powder. lemon verbena South American herb, Lippia citriodora, used to flavour drinks and salads. lentils legumes; dried seeds of many varieties of Lens esculenta, they may be green, yellow or orange-red.

Composition/100g: water 11.2g, 1415kJ (338kcal), protein 28.1 g, fat 1g, carbohydrate 57.1g (5.4g sugars), fibre 30.5g, ash 2.7g, Ca 51 mg, Fe 9mg, Mg 107mg, P 454mg, K 905mg, Na 10 mg, Zn 3.6mg, Cu 0.9mg, Mn 1.4mg, Se 8.2|g, vitamin A 2|g RE (23 |g carotenoids), E 0.3 mg, K 5 mg, B1 0.47 mg, B2 0.25 mg, niacin 2.6 mg, B6 0.54mg, folate 433 |g, pantothenate 1.8 mg, C 6 mg. An 85 g serving is a source of vitamin B2, niacin, a good source of Zn, vitamin B1, B6, pantothenate, a rich source of Cu, Fe, Mg, Mn, P, folate. leptin A peptide hormone synthesised in adipose tissue which acts to regulate appetite in response to the adequacy or otherwise of body fat reserves. Its crystal structure suggests that it is a member of the cytokine family. The ob gene (defective in the ob/ob genetically obese mouse) codes for leptin; the db gene (defective in the db/db genetically obese diabetic mice) codes for the hypothalamic leptin receptor. lettuce Leaves of the plant Lactuca sativa; many varieties are grown commercially.

Composition/100g: (edible portion 94%) water 95g, 71 kJ (17kcal), protein 1.2g, fat 0.3g, carbohydrate 3.3g (1.2g sugars), fibre 2.1 g, ash 0.6g, Ca 33 mg, Fe 1 mg, Mg 14mg, P 30mg, K 247 mg, Na 8mg, Zn 0.2mg, Mn 0.2mg, Se 0.4 |g, vitamin A 290 |g RE (5796|g carotenoids), E 0.1 mg, K 102.5mg, B1 0.07mg, B2 0.07mg, niacin 0.3 mg, B6 0.07 mg, folate 136|g, pantothenate 0.1 mg, C 24 mg. A 20g serving is a source of folate. leucine An essential amino acid; rarely limiting in foods; abbr Leu (L), Mr 131.2, p^a 2.33, 9.74, codons UUPu, CUNu. Chemically, amino-isocaproic acid. leucocytes White blood cells, normally 5000-9000/mL; includes polymorphonuclear neutrophils, lymphocytes, monocytes, poly-morphonuclear eosinophils and polymorphonuclear basophils. A 'white cell count' determines the total; a differential cell count estimates the numbers of each type. Fever, haemorrhage and violent exercise cause an increase (leucocytosis); starvation and debilitating conditions a decrease (leucopenia). leucocytosis Increase in the number of leucocytes in the blood. leucopenia Decrease in the number of leucocytes in the blood. leucosin One of the water-soluble proteins of wheat flour. leucovorin See folinic acid.

levans Polymers of fructose (the main one is inulin) that occur in tubers and some grasses. levitin One of the proteins of egg yolk; about 20% of the total, the remainder being vitellin. Rich in sulphur, accounting for half of the sulphur in the yolk. Leyden Dutch semi-hard cheese containing caraway and cumin seeds.

Leyden hutsput Dutch; hotpot made from (stale) beef and root vegetables, traditionally served on 3 October, together with white bread and herrings, to celebrate the relief of the siege of Leyden (1574). licorice See liquorice.

Lieberkuhn, crypts of Glands lining the small intestine which secrete the intestinal juice. Liebermann-Burchard reaction Colorimetric reaction for cholesterol; the development of a blue colour on reaction with acetic anhydride and sulphuric acid. light (or lite) As applied to foods usually indicates:

(1) a lower content of fat compared with the standard product (e.g. breadspreads, sausages);

(2) sodium chloride substitutes lower in sodium (see salt, light);

(3) low-alcohol beer or wine.

US legislation restricts the term light to modified foods that contain one-third less energy or half the fat of a reference unmodified food, or to those where the sodium content of a low-fat, low-calorie food has been reduced by half.

See also fat free; free from; low in; reduced. lights Butchers' term for the lungs of an animal. lignans Naturally occurring compounds in various foods that have both oestrogenic and antioestrogenic activity (see phytoestrogens); may provide some protection against breast and uterine cancer, and have activity in menopausal hormone replacement therapy. lignin (lignocellulose) A polymer of aromatic alcohols, in plant cell walls; included in measurement of dietary fibre, but not of non-starch polysaccharide. limb fat area Cross-sectional area of arm or leg fat, calculated from skinfold thickness and limb circumference, as an index of total body fat.

See also anthropometry. Limburger Originally Belgian, strong flavoured soft cheese. lime The fruit of Citrus aurantifolia, cultivated almost solely in the tropics, since it is not as hardy as other citrus fruits. Used to prevent scurvy in the British Navy (replacing, at the time, lemon juice) and so giving rise to the nickname of 'Limeys' for British sailors and for British people in general.

Composition/100g: (edible portion 84%) water 88g, 126kJ (30 kcal), protein 0.7 g, fat 0.2 g, carbohydrate 10.5 g (1.7g sugars), fibre 2.8 g, ash 0.3 g, Ca 33 mg, Fe 0.6 mg, Mg 6mg, P 18mg, K 102mg, Na 2mg, Zn 0.1 mg, Cu 0.1 mg, Se 0.4|g, vitamin A 2|g RE (30|g carotenoids), E 0.2mg, K 0.6mg, B1 0.03mg, B2 0.02mg, niacin 0.2mg, B6 0.04mg, folate 8 |g, pantothenate 0.2 mg, C 29 mg. A 60 g serving is a good source of vitamin C.

limit dextrin See dextrins. Limmisax™ See saccharin.

Limmits™ A 'slimming' preparation composed of wholemeal biscuits with a methyl cellulose mixture as filling, containing some vitamins and minerals; intended as a meal replacement. limonin The bitter principle in the albedo of the Valencia orange. Isolimonin in the navel orange. Both are present as a non-bitter precursor which is liberated into the juice during extraction and is slowly hydrolysed, making the juice bitter. limonoids Family of highly oxygenated triterpene derivatives found as aglycones in citrus seeds and peel oil, and as glucosides in juice; responsible for delayed bitterness of the fruit, and potentially protective against cancer. limosis Abnormal hunger or excessive desire for food. linamarin Cyanogenic (cyanide forming) glucoside found in cassava (manioc) which may be a cause of neuropathies in areas where cassava is major food; the cyanide is removed in traditional processing by grating and exposing to air. ling Bottom-dwelling (demersal) fish (Geypterus blacodes), a member of the cusk eel family; mainly caught around New Zealand.

Composition/100g: water 79.6g, 364kJ (87kcal), protein 19 g, fat 0.6 g, cholesterol 40 mg, carbohydrate 0g, ash 1.4 g, Ca 34mg, Fe 0.6mg, Mg 63mg, P 198mg, K 379mg, Na 135mg, Zn 0.8mg, Cu 0.1mg, Se 36.5 |g, vitamin A 30|g RE (30|g retinol, B1 0.11mg, B2 0.19 mg, niacin 2.3 mg, B6 0.3 mg, folate 7 |g, B12 0.6 |g, pantothenate 0.3 mg. A 100g serving is a source of vitamin B2, niacin, B6, a good source of Mg, P, a rich source of Se, vitamin B12.

linguic Portuguese; pork sausage seasoned with garlic, cinnamon and cumin, cured in brine. linguini See pasta.

linoleic acid An essential polyunsaturated fatty acid (C18:2 o>6), predominant in most edible vegetable oils.

linoleic acid, conjugated Isomers of linoleic acid in which two or more of the double bonds are conjugated (i.e. alternating with single bonds) rather than separated by a methylene bridge. a-linolenic acid An essential polyunsaturated fatty acid (C18:3 m3).

g-linolenic acid A non-essential polyunsaturated fatty acid (C18:3 rn6), which has some pharmacological actions. Found in oils from the seeds of evening primrose, borage and blackcurrant. linseed See flaxseed.

liothyronine Obsolete name for the thyroid hormone tri-

iodothyronine (T3). lipaemia Increase in blood lipids, as occurs normally after a meal. lipase Enzyme (EC 3.1.1.x) that hydrolyses triacylglycerols to free fatty acids and 2-mono-acylglycerol. Lipase secreted by the tongue and in gastric and pancreatic juice is EC 3.1.1.3; lipases are also present in many seeds and grains. Final hydrolysis to yield glycerol is catalysed by acylglycerol lipase (EC 3.1.1.23).

Most lipases have low specificity and will hydrolyse any triacylglycerol. Sometimes responsible for the development of (hydrolytic) rancidity in stored foods, and the development of flavour in cheese.

See also acid number; interesterification. lipase, clearing factor See lipase, lipoprotein. lipase, hormone-sensitive lipase in adipose tissue that is activated in response to adrenaline, and inactivated in response to insulin, so controlling release of free fatty acids as a metabolic fuel.

lipase, lipoprotein lipase (EC 3.1.1.34) in muscle and adipose tissue that is responsible for the uptake of free fatty acids from triacylglycerols in lipoproteins. Also known as clearing factor lipase, since it removes triacylglycerol from chylomicrons after a meal, resulting in reduction in their size, and clearing of the milky appearance of chylomicron-rich plasma. lipectomy Surgical removal of subcutaneous fat. lipidema Condition in which fat deposits accumulate in the lower extremities, from hips to ankles, with tenderness of the affected parts.

lipids (also sometimes lipides, lipins) A general term for fats and oils (chemically triacylglycerols), waxes, phospholipids, steroids and TERPENES.Their common property is insolubility in water and solubility in hydrocarbons, chloroform and alcohols. Fats are solid at room temperature, while oils are liquids.

Non-saponifiable lipids are not hydrolysed by treatment with sodium or potassium hydroxide and therefore cannot be extracted into an aqueous medium: cholesterol and other sterols, squalene, carotenoids and vitamins a, d, e and k. The saponifiable lipids are triacylglycerols (and mono- and diacyl-glycerols) and phospholipids, which can be extracted into an aqueous medium after alkaline hydrolysis (saponification). lipids, plasma Total blood lipid concentration in the fasting state is about 590 mg per 100 mL plasma: 150 mg triacylglycerols, 160mg (4mmol) cholesterol, 200 mg phospholipids, mainly in the plasma lipoproteins. After a meal the total fat increases, as a result of the chylomicrons containing the recently absorbed dietary fat.

See also lipoproteins, plasma. lipochromes Plant pigments soluble in lipids and organic solvents, e.g. chlorophyll, carotenoids. lipodystrophy Abnormality in the metabolism or deposition of fats; abnormal pattern of subcutaneous fat deposits. lipofuscin A group of pigments that accumulate in several body tissues, particularly the myocardium, during life and are consequently associated with the ageing process. lipoic acid 1,2-Dithiolane-3-valeric acid (6,8-thioctic acid), coenzyme in the oxidative decarboxylation of pyruvate, a-ketoglutarate and branched-chain keto-acids. Not a dietary essential.

lipolysis Hydrolysis of triacylglycerols to mono- and diacylglyc-

erols, glycerol and free fatty acids, catalysed by lipase. lipolytic rancidity Spoilage of foods as a result of hydrolysis of fats to free fatty acids on storage (by the action of lipase, either bacterial lipase or the enzyme naturally present in the food). Since the enzyme is inactivated by heat, occurs only in uncooked foods.

See also acid number. lipoprotein [a] (Lp[a]) Complex of low-density lipoprotein in which an additional protein, apo-a, is bound to apo-protein B-100 by a disulphide bridge. It is genetically determined and there is a strong association between Lp[a] and coronary artery disease.

lipoproteins, plasma Lipids, encased in protein, in the blood plasma.

Chylomicrons are assembled in the intestinal mucosa, and contain the products of digestion of dietary fat. They are absorbed into the lymphatic circulation, and enter the bloodstream at the thoracic duct. Triacylglycerol is hydrolysed by lipoprotein lipase in adipose tissue and muscle, and the chy-lomicron remnants are cleared by the liver.

Very low-density lipoproteins are secreted by the liver, containing newly synthesised triacylglycerol and that from chylomi-

cron remnants, and cholesterol; hydrolysis by lipoprotein lipase in muscle and adipose tissue yields progressively intermediate density and then low-density lipoprotein (LDL). LDL is normally cleared by the liver, but oxidative damage may prevent uptake by the liver, when macrophages scavenge LDL, leading to the formation of foam cells and the development of atherosclerotic plaque.

High-density lipoprotein is secreted by the liver as the apo-protein, and accumulates cholesterol from tissues, which is normally transferred to LDL for clearance by the liver. liposis See adiposis.

liposuction Procedure for removal of subcutaneous adipose tissue in obese people using a tube inserted through the skin at different locations. lipotropes (lipotrophic factors) Compounds such as choline, betaine and methionine that act as methyl donors; deficiency may result in fatty infiltration of the liver. lipovitellenin A lipoprotein complex in egg comprising about

15% of the solids of the yolk. lipoxygenase Enzyme (EC 1.13.11.12) that catalyses the oxidation of polyunsaturated fatty acids to trans-hydroperoxides (an intermediate step in prostaglandin synthesis); in plant oils may be important in the development of oxidative rancidity. Lipoxygenase from soya or fava bean flour is used in breadmaking to improve mixing tolerance and dough stability; it also bleaches carotenoids and other lipid pigments in the flour. liptauer Hungarian; cheese spread made from sheep and cow milk.

liqueurs Distilled, flavoured and sweetened alcoholic liquors, normally 20-40% alcohol by volume. liquid oleo See premier jus. liquid paraffin See medicinal paraffin.

liquorice Used in confectionery and to flavour medicines; liquorice root and extract are obtained from the plant Gly-cyrrhiza glabra; stick liquorice is the crude evaporated extract of the root. The plant has been grown in the Pontefract district of Yorkshire since the 16th century; hence the name Pontefract cakes for the sugar confection of liquorice.

See also glycyrrhizin. Listeria A genus of bacteria commonly found in soil, of which the commonest is Listeria monocytogenes. They can cause food poisoning (listeriosis). Listeria spp. are especially found in unwashed vegetables and some soft cheeses; they resist cold and the presence of salt and can multiply in a refrigerator. Symptoms of listeriosis are flu-like, with high fever and dizziness. Pregnant women, babies and the elderly are especially at risk. L. monocytogenes causes systemic infection; minimum infective dose not known; onset within days, duration weeks. listeriosis See listeria. LitaTM fat replacer made from protein. litchi See lychee. lite See light.

lithium Metal not known to have any physiological function, although it occurs in food and water; lithium salts are used in the treatment of bipolar manic-depressive disease. lithocholic acid One of the secondary bile salts, formed by intestinal bacterial metabolism of chenodeoxycholic acid. liver Usually from calf, pig, ox, lamb, chicken, duck or goose.

Composition/100 g (depending on source, beef, calf, lamb or poultry): water 71-76g, 500-570kJ (120-140kcal), protein 1620 g, fat 4-5 g (of which: beef liver 55% saturated, 23% mono-unsaturated, 23% polyunsaturated; calf liver 47% saturated, 29% mono-unsaturated, 24% polyunsaturated; chicken liver 44% saturated, 33% mono-unsaturated, 22% polyunsaturated; duck liver 52% saturated, 26% mono-unsaturated, 22% polyunsaturated; goose liver 59% saturated, 30% mono-unsaturated, 11% polyunsaturated), cholesterol 275-515 mg, carbohydrate 3-6 g, ash 1.1-1.3g, Ca 5-43mg, Fe 5-30mg, Mg 18-24mg, P 260-380mg, K 230-310 mg, Na 70-140 mg, Zn 3-12 mg, Cu 3-12 mg, Mn 0.3 mg, Se 20-70|g, vitamin A 5000-12000|g retinol, E 0.4mg, K 1-3 mg, B1 0.2-0.6mg, B2 0.9-2.8 mg, niacin 7-13 mg, B6 0.8-1 mg, folate 125-740|g, B12 17-60|g, pantothenate 6-7 mg, C 1-18mg. A 100g serving is a source of Mn, vitamin B1, a good source of Zn, a rich source of Cu, Fe, P, Se, vitamin A, B2, niacin, B6, folate, B12, pantothenate.

The vitamin A content of liver is high enough for it to pose a possible hazard to unborn children, and pregnant women have been advised not to eat liver. See vitamin a toxicity.

Fish liver is a particularly rich source of vitamins A and D, as well as long-chain polyunsaturated fatty acids, and fish liver oils (especially cod and halibut) are used as sources of these vitamins as nutritional supplements. livetin A water-soluble protein in egg yolk. lobster Crustacean, Homarus vulgaris.

Composition/100g: water 77g, 377kJ (90kcal), protein 18.8g, fat 0.9 g, cholesterol 95 mg, carbohydrate 0.5 g, ash 2.2 g, Ca 48 mg, Fe 0.3 mg, Mg 27 mg, P 144 mg, K 275 mg, Na 296 mg, Zn 3 mg, Cu 1.7mg, Mn 0.1 mg, Se 41.4 |g, I 100 |g, vitamin A 21 |g RE (21 |g retinol), E 1.5mg, K 0.1mg, B1 0.01mg, B2 0.05mg, niacin 1.5 mg, B6 0.06mg, folate 9 |g, B12 0.9 |g, pantothenate 1.6mg, A 250g serving is a source of Ca, folate, a good source of Mg, niacin, a rich source of Cu, I, P, Se, Zn, vitamin E, B12, pantothenate. lobster, rock or spiny See crawfish. Locasol™ A low-calcium milk substitute. locksoy Chinese fine-drawn rice macaroni. locoweed Astralagus and Oxytropus spp., common in arid areas of western USA. Toxic to cattle, causing locoism: neurological damage, abortion and birth defects. Apparently caused by an alkaloid, swainsonine, which is also found in mouldy hay. locust bean (1) carob seed. (2) African locust bean, Parkia spp. Loeb membrane Thin layer of membrane used in reverse osmosis (see osmosis, reverse) supported on thicker layer of porous support material. Lofenalac™ Food low in phenylalanine for treatment of phenylketonuria. Logan Bar Ration D See iron ration.

loganberry Cross between European raspberry and Californian blackberry, Rubus ursinus var. loganobaccus, named after James Harvey Logan, Californian judge, 1881.

Composition/100g: water 84.6 g, 230kJ (55kcal), protein 1.5 g, fat 0.3g, carbohydrate 13g (7.7g sugars), fibre 5.3 g, ash 0.5g, Ca 26 mg, Fe 0.6 mg, Mg 21 mg, P 26 mg, K 145 mg, Na 1mg, Zn 0.3 mg, Cu 0.1 mg, Mn 1.2mg, Se 0.2 |g, vitamin A 2 |g RE (139|g carotenoids), E 0.9mg, K 7.8mg, B1 0.05mg, B2 0.03mg, niacin 0.8 mg, B6 0.06mg, folate 26|g, pantothenate 0.2mg, C 15mg. A 110g serving is a source of folate, a good source of vitamin C, a rich source of Mn. logarithmic phase The most rapid period of bacterial growth, when the numbers increase in geometric progression. Under ideal conditions bacteria can double in number every 20min. lo han kuo See mogroside. Lonalac™ A milk preparation free from sodium. London broil American name for steak, broiled or grilled and sliced thinly against the grain. longan Fruit of the tree Euphoria longan, native of China, related to the lychee.

Composition/100g: (edible portion 53%) water 83g, 251 kJ (60kcal), protein 1.3 g, fat 0.1 g, carbohydrate 15.1 g, fibre 1.1 g, ash 0.7g, Ca 1mg, Fe 0.1 mg, Mg 10mg, P 21 mg, K 266mg, Zn 0.1 mg, Cu 0.2 mg, Mn 0.1 mg, B1 0.03mg, B2 0.14mg, niacin 0.3 mg, C 84mg.

loofah Young fruit of the curcubit Luffa acutangula is edible, but becomes too bitter as it matures. loonzein Rice from which the husk has been removed; also known as brown rice, hulled rice and cargo rice.

loperamide See antidiarrhoeal agents; antimotility agents. loquat The small pear-shaped fruit of Eriobotyra japonica, a member of the apple family, also known as Japanese medlar or plum.

Composition/100g: (edible portion 65%) water 86.7g, 197kJ (47 kcal), protein 0.4g, fat 0.2g, carbohydrate 12.1 g, fibre 1.7g, ash 0.5 g, Ca 16mg, Fe 0.3mg, Mg 13mg, P 27mg, K 266 mg, Na 1mg, Zn 0.1 mg, Mn 0.1 mg, Se 0.6 |g, vitamin A 76 |g RE, B1 0.02 mg, B2 0.02 mg, niacin 0.2mg, B6 0.1 mg, folate 14 |g, C 1 mg. loss factor A measure of the amount of energy that a material will dissipate when subjected to an alternating electric field (in microwave and dielectric heating). Also termed the 'dielectric loss' or 'loss tangent'. lotus The sacred lotus of India and China, Nelumbium nuciferum, a water plant whose rhizomes and seeds are eaten.

Rhizome, composition/100g: (edible portion 79%) water 79g, 310kJ (74kcal), protein 2.6g, fat 0.1 g, carbohydrate 17.2g, fibre 4.9 g, ash 1g, Ca 45mg, Fe 1.2mg, Mg 23mg, P 100mg, K 556mg, Na 40mg, Zn 0.4mg, Cu 0.3mg, Mn 0.3mg, Se 0.7 |g, B1 0.16mg, B2 0.22mg, niacin 0.4mg, B6 0.26mg, folate 13 |g, pantothenate 0.4mg, C 44mg.

Seeds, composition/100g: water 14.2g, 1390kJ (332kcal), protein 15.4g, fat 2g (of which 16% saturated, 21% mono-unsaturated, 63% polyunsaturated), carbohydrate 64.5 g, ash 4g, Ca 163mg, Fe 3.5mg, Mg 210mg, P 626mg, K 1368mg, Na 5mg, Zn 1mg, Cu 0.3 mg, Mn 2.3 mg, vitamin A 3 |g RE (B1 0.64 mg, B2 0.15 mg, niacin 1.6 mg, B6 0.63 mg, folate 104 |g, pantothenate 0.9mg. A 15g serving is a source of Mn, P. lovage Herb of the carrot family, Ligusticum scoticum, with a strong musky scent of celery. The stems can be candied like angelica or used as a vegetable, and the leaves and stems are used in soup. The seeds can also be used as a seasoning, with a flavour like dill or fennel seed. lovastatin See statins. love apple Old name for tomato.

low birth weight Infants born weighing significantly less than normal (2.5-4.5 kg) are considered to be premature; their chances of survival and normal development are considerably improved if they are fed special formula preparations to meet their needs, rather than being breast fed or fed normal infant formula.

low in EU legislation states that for a food label or advertising to bear a claim that it is low in fat, saturates, cholesterol, sodium or alcohol, it must provide less than half of the amount of the specified nutrient of a reference product for which no claim is made. US legislation sets precise levels at which claims may be made.

Lowry reaction Sensitive technique for colorimetric determination of protein using the Folin-Cioucalteau tungstate, molybdate, phosphate reagent, which reacts with tyrosine in proteins. Sensitivity 1ng/mL, maximum absorbance 660 nm.

lox American (originally Yiddish) name for smoked salmon; see also lax.

lozenges Shapes stamped out of mixture of icing sugar, glucose syrup and gum arabic or gelatine with flavourings, then hardened at 32-43 °C.

LRNI Lower reference nutrient intake; see reference intakes.

LSMtm A low-sodium milk containing 50mg/L; ordinary milk contains 500mg/L.

lucerne See alfalfa.

luciferase An enzyme that catalyses an ATP-dependent oxidation of a bioluminescent compound (luciferins of various types), leading to emission of visible light. Widely used as a reporter gene in genetic engineering, and for assay of atp. Firefly luciferase is EC 1.13.12.7, bacterial luciferase is EC 1.14.14.3.

Luff-Schoorl method For determination of starch and sugars. Sugars are extracted using ethanol, then starch is hydrolysed using hydrochloric acid and the resultant glucose is extracted after neutralisation. Sugars are determined in the extracts after oxidation using copper reagent, linked to the reduction of potassium iodide to iodine, and titration of iodine with sodium thiosulphate.

luganeghe Italian; pork sausage that is not twisted into links.

lumichrome Product of ultraviolet irradiation of riboflavin (vitamin b2) in neutral solution; some is formed in vivo on exposure to sunlight and is excreted in the urine. May also arise as a result of intestinal bacterial metabolism of riboflavin. Formed in milk on exposure to sunlight.

See also lumiflavin; sunlight flavour.

lumiflavin Product of ultraviolet irradiation of riboflavin (vitamin b2) in alkaline solution; soluble in chloroform, and provides the basis of a fluorimetric assay for the vitamin.

See also lumichrome.

luminacoids Japanese term, introduced 2003, to include all oligosaccharides, polyols, resistant starch, indigestible dextrins, resistant proteins and other compounds of plant or animal origin that may undergo (bacterial) metabolism in the intestinal lumen; a broader definition than either dietary fibre or non-starch polysaccharide.

lumpfish Large sea fish, Cylopterus lumpus, the eggs of which are salted, pressed and coloured, as Danish or German caviare. luncheon meat Precooked, canned meat, usually pork.

lupeose See stachyose.

lupins Legumes, Lupinus spp. The ordinary garden lupin contains toxic quinolizidine alkaloids and tastes bitter; varieties selected for animal feed and grain crop, low in alkaloids, are known as sweet lupins; rich in protein and fat. lupulones Aromatic acids in hops, see humulones. lutein A hydroxylated carotenoid (a xanthophyll); not vitamin a active, but may be an important antioxidant nutrient.Together with zeaxanthin accumulates in the retina, and considered to be protective against damage by uv and blue light. luteotrophin (luteotrophic hormone) See prolactin. luxus konsumption See diet-induced thermogenesis. Lycasin™ Hydrogenated glucose syrup, a bulk sweetener. lychee (litchi) The fruit of Litchi chinensis, native of China; the size of a small plum, with a hard case and translucent white jellylike sweet flesh surrounding the seed.

Composition/100 g: (edible portion 60%) water 81.8 g, 276 kJ (66kcal), protein 0.8g, fat 0.4g, carbohydrate 16.5g (15.2g sugars), fibre 1.3g, ash 0.4g, Ca 5mg, Fe 0.3mg, Mg 10mg, P 31 mg, K 171 mg, Na 1 mg, Zn 0.1 mg, Cu 0.1 mg, Mn 0.1 mg, Se 0.6 |g, Vitamin E 0.1 mg, K 0.4mg, B1 0.01 mg, B2 0.06mg, niacin 0.6 mg, B6 0.1 mg, folate 14 |g, C 72 mg. A 50g serving (5 fruits) is a rich source of vitamin C. lycopene A carotenoid, not vitamin a active, found especially in tomatoes. It does not have a characteristic ionone ring; both rings are open. Epidemiological evidence suggests that it may be associated with lower incidence of cardiovascular disease and cancer of the prostate and gastrointestinal tract. Sometimes used as a food colour (E-160d). lye-peeling A method of removing skins from vegetables by immersion in hot caustic soda solution (lye) followed by tumbling in a wash to remove the skin and chemicals. lymph The fluid between blood and the tissues; the medium in which oxygen and nutrients are conveyed from the blood to the tissues, and waste products back to the blood. Similar to blood plasma in composition. Dietary fat is absorbed into the lacteals (lymphatic vessels of the intestinal villi) as chylomicrons which are formed in the intestinal mucosa, and enters the bloodstream at the thoracic duct. After a fatty meal, the lymph is rich in emulsified fat and is called chyle. lymphatics Vessels through which the lymph flows, draining from the tissues and entering the bloodstream at the thoracic duct.

lymphocytes See leucocytes. lymphokine See cytokine.

lyophilic A solute that has a high affinity for the solvent medium.

When the solvent is water the term hydrophilic is used. lyophilisation See freeze drying.

lyophobic A solute that has little or no affinity for the solvent medium. When the solvent is water the term hydrophobic is used. lysergic acid The toxin of ergot.

lysine An essential amino acid, abbr Lys (K), Mr 146.2, pKa 2.16, 9.18,10.79, codons AAPu. Of nutritional importance, since it is the limiting amino acid in many cereals. lysinoalanine An amino acid formed when proteins are heated or treated with alkali by reaction between e-amino group of lysine and dehydroalanine formed from cysteine or serine. Present in many foods at about 1000ppm. Although high doses cause kidney tubule lesions (nephrocytomegaly) in rats, it is not considered hazardous to health. lysolecithin lecithin from which the fatty acid at carbon-2 has been removed.

lysozyme An enzyme (EC 3.2.1.17) that hydrolyses high molecular weight carbohydrates of bacterial cell walls, and so lyses bacteria. Widely distributed (e.g. in tears); egg white is especially rich.

lyxoflavin An analogue of riboflavin isolated from human heart muscle, containing the sugar lyxose; its function is unknown.

lyxulose See xylulose.

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