Tự điển Food Science, Technology And Nutrition - Vần D

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144 cytochromes haem-containing proteins. Some react with oxygen directly; others are intermediates in the oxidation of reduced coenzymes. Unlike haemoglobin, the iron in the haem of cytochromes undergoes oxidation and reduction. cytochromes P450 A family of cytochromes involved in the detoxication system of the body (see phase i metabolism). They act on a wide variety of (potentially toxic) compounds, both endogenous metabolites and foreign compounds (xenobiotics), rendering them more water-soluble, and more readily conjugated for excretion in the urine. The CYP26 group of cytochromes P450 are speciﬁc for retinoic acid, leading to a variety of metabolites that may be physiologically active (especially in cell differentiation), includ- ing 4-hydroxy-, 4-oxo-, 5,6-epoxy- and 18-hydroxy-retinoic acid. cytokines A number of proteins secreted by cells in response to various stimuli that act to regulate proliferation and differentia- tion, immune and inﬂammatory responses, etc. Cytokines produced by lymphocytes are sometimes known as lymphokines; those from monocytes as monokines; those secreted by adipose tissue as adipokines or adipocytokines. cytokinins Plant hormones derived from isopentenyl adenosine; produced by root tips, seed embryos, developing fruits and buds; they stimulate cell division (cytokinesis) and regulate develop- ment of the plant. See also auxins. cytosine One of the pyrimidine bases of nucleic acids. D D-, L- and DL- Preﬁxes to chemical names for compounds that have a centre of asymmetry in the molecule, and which can therefore have two forms. Most naturally occurring sugars have the d-conformation; apart from a few microbial proteins and some invertebrate peptides, all the naturally occurring amino acids have the l- conﬁguration. Chemical synthesis yields a mixture of the d- and l-isomers (the racemic mixture), generally shown as dl-. See also isomers; optical activity; R- and S-. d- and l- An obsolete way of indicating dextrorotatory and laevorotatory optical activity, now replaced by (+) and (−). dabberlocks Edible seaweed, Alaria esculenta. dadhi See milk, fermented. dagé Indonesian; fermented presscake from various oilseeds or legumes or starch crops, soaked in water and left to undergo
145 bacterial fermentation (mainly Bacillus spp.) to form a glutinous mass bound by bacterial polysaccharides. dahl See legumes. dahlin See inulin. daikon Radish, large Japanese variety of Raphanus sativus. Often pickled in soy sauce, and an ingredient of kimchi. daily value Reference amounts of energy, fat, saturated fat, car- bohydrate, ﬁbre, sodium, potassium and cholesterol, as well as protein, vitamins and minerals, introduced for food labelling in USA in 1994. The nutrient content of a food must be declared as percentage of the daily value provided by a standard serving. Dairy-LoTM fat replacer made from protein. DaltoseTM A carbohydrate preparation consisting of maltose, glucose and dextrin for infant feeding. damiana Leaf and stem of Turnera difﬁusa var. aphrodisiaca, used as a food ﬂavouring, reputed to have aphrodisiac and antide- pressant properties. damson Small dark purple plum (Prunus damascena); very acid, mainly used to make jam. Introduced into Europe by Crusaders returning from Damascus (early 13th century). dandelion The leaves of the weed Taraxacum ofﬁcinale may be eaten as a salad or cooked. In France dandelion greens are known as pis-en-lit because of their diuretic action. Composition/100 g: water 86 g, 188 kJ (45 kcal), protein 2.7 g, fat 0.7 g, carbohydrate 9.2 g (3.8 g sugars), ﬁbre 3.5 g, ash 1.8 g, Ca 187 mg, Fe 3.1 mg, Mg 36 mg, P 66 mg, K 397 mg, Na 76 mg, Zn 0.4 mg, Cu 0.2 mg, Mn 0.3 mg, Se 0.5 µg, vitamin A 247 µg RE (9607 µg carotenoids), E 4.8 mg, K 273.7 mg, B1 0.19 mg, B2 0.26 mg, niacin 0.8 mg, B6 0.25 mg, folate 27 µg, pantothenate 0.1 mg, C 35 mg. The root can be cooked as a vegetable, or may be roasted and used as a substitute for coffee. Danish agar See furcellaran. dansyl reagent 5-Dimethylamino naphthalene sulphonic acid; reacts with amino terminal amino acid of a peptide to give a ﬂu- orescent derivative which can be identiﬁed by thin-layer chro- matography after hydrolysis of the peptide. danthron An anthroquinone stimulant laxative. dark adaptation In the eye, the visual pigment rhodopsin is formed by reaction between vitamin a aldehyde (retinaldehyde) and the protein opsin, and is bleached by exposure to light, sti- mulating a nerve impulse (this is the basis of vision). At an early stage of vitamin A deﬁciency it takes considerably longer than normal to adapt to see in dim light after exposure to normal bright light, because of the limitation of the amount of rhodopsin
146 that can be reformed. Measuring the time taken to adapt to dim light (the dark adaptation time) provides a sensitive index of early vitamin A deﬁciency. More severe vitamin A deﬁciency results in night blindness, and eventually complete blindness. dasheen See taro. date Fruit of date palm, Phoenix dactylifera. Three types: ‘soft’ (about 80% of the dry matter is invert sugar, see sugar, invert); semi-dry (about 40% invert sugar, 40% sucrose); and dry (20–40% invert sugar, 40–60% is sucrose). Composition/100 g: (edible portion 90%) water 20.5 g, 1180 kJ (282 kcal), protein 2.5 g, fat 0.4 g, carbohydrate 75 g (63.3 g sugars), ﬁbre 8 g, ash 1.6 g, Ca 39 mg, Fe 1 mg, Mg 43 mg, P 62 mg, K 656 mg, Na 2 mg, Zn 0.3 mg, Cu 0.2 mg, Mn 0.3 mg, Se 3 µg, 81 µg carotenoids, vitamin E 0.1 mg, K 2.7 mg, B1 0.05 mg, B2 0.07 mg, niacin 1.3 mg, B6 0.17 mg, folate 19 µg, pantothenate 0.6 mg. date, Chinese See jujube (2). DATEM Diacetyl tartaric esters of mono- and diglycerides used as emulsiﬁers to strengthen bread dough and delay staling (E- 472e). date marking ‘Best before’ is the date up until when the food will remain in optimum condition, i.e. will not be stale. Foods with a shelf-life up to 12 weeks are marked ‘best before day, month, year’; foods with a longer shelf-life are marked ‘best before end of month, year’. Perishable foods with a shelf-life of less than a month may have a ‘sell by’ date instead. ‘Use by’ date is given for foods that are microbiologically highly perishable and could become a danger to health; it is the date up to and including which the food may safely be used if stored properly. Frozen foods and ice cream carry star markings that corre- spond to the star marking on freezers and frozen food compart- ments of refrigerators. One star (*) −4 °C (25 °F) will keep for one week; two star (**) −11 °C (12 °F), 1 month; three star (***) −18 °C (0 °F), 3 months. Corresponding times for ice cream are 1 day, 1 week, 1 month, after which they are ﬁt to eat but the texture changes. date plum See persimmon. dawadawa African; fermented dried seeds of the African locust bean Parkia biglobosa, usually pressed into balls; various bacte- ria are involved in the 3–4 day fermentation. db/db mouse Genetically obese mouse that is also diabetic; the defect is lack of leptin receptors. DBD process See dry–blanch–dry process. DCPIP See dichlorophenolindophenol. DCS Distributed control systems.
147 DE See dextrose equivalent value. debranching enzymes Enzymes that hydrolyse the α-1,6 glyco- side bonds that form the branch points in amylopectin. Amy- loglucosidase (EC 3.2.1.3) and glucoamylase (EC 3.2.1.20) also hydrolyse α-1,4 links; pullulanase (EC 3.2.1.41) and isoamylase (EC 3.2.1.68) hydrolyse only α-1,6 links. See also amylases; z-enzyme. debrining Removal of much of the salt used in brining vegeta- bles, to a level that will be acceptable in the ﬁnal product. Also known as freshening. decimal reduction time (D value) Term used in sterilising canned food, etc.; the duration of heat treatment required to reduce the number of micro-organisms to one-tenth of the initial value, with the temperature shown as a subscript, e.g. D121 is time at 121 °C. defoamer See antifoaming agents. DEFRA UK Department of the Environment, Food and Rural Affairs; web site http://www.defra.gov.uk/. defructum Roman; cooking wine that has been reduced to half its volume by boiling. DEFT Direct Epiﬂuorescence Filter Technique for measuring bacterial content of milk and other ﬂuids by passing through a ﬁne pore ﬁlter to retain bacteria that are then stained with acri- dine orange to permit ﬂuorimetric quantiﬁcation. A rapid and sensitive alternative to plating out a sample, culturing and count- ing the resultant bacterial colonies. Trade names for the equip- ment used include Biofoss, Bactoscan and Autotrak. deglutition The act of swallowing. degumming Removal of proteins, phospholipids, gum, resin, etc. in the reﬁning of oils and fats by the addition of dilute hydrochlo- ric or phosphoric acid, brine or alkaline phosphate solution. Permits recovery of lecithin from the aqueous phase. dehydroascorbic acid The oxidised form of vitamin c which is readily reduced back to the active form in the body, and there- fore has vitamin activity. Not measured by all methods for vitamin C estimation. See also ascorbic acid. dehydrocanning A process in which 50% of the water is removed from a food before canning. The advantages are that the texture is retained by the partial dehydration and there is a saving in bulk and weight. 7-dehydrocholesterol Intermediate in the synthesis of choles- terol, and precursor for the synthesis of vitamin d in the skin. dehydrofreezing A process for preservation of fruits and vegeta- bles by evaporation of 50–60% of the water before freezing. The texture and ﬂavour are claimed to be superior to those resulting
148 from either dehydration or freezing alone, and rehydration is more rapid than with dehydrated products. dehydroretinol An analogue of vitamin a found in freshwater ﬁsh, which has about half the biological activity of retinol. For- merly termed vitamin A2. Delaney Amendment Clause in the US Federal Food, Drug and Cosmetic Act (1958) which states that no food additive shall be deemed safe (and therefore may not be used) after it is found to induce cancer when ingested by man or animals, at any dose level. delayed hypersensitivity An adverse reaction to food, occurring several hours after ingestion, caused by cell-mediated immune responses (activated lymphocytes) as opposed to immunoglobu- lin-mediated responses, which occur rapidly. See also coeliac disease. demerara sugar See sugar. denaturation A normally irreversible change in the structure of protein by heat, acid, alkali or other agents which results in loss of solubility and coagulation. Denatured proteins lose biologi- cal activity (e.g. as enzymes), but not nutritional value. Indeed, digestibility is improved compared with the native structure, which is relatively resistant to enzymic hydrolysis. denatured alcohol See alcohol, denatured. dendritic salt A form of ordinary table salt, sodium chloride, with the crystals branched or star-like (dendritic) instead of the normal cubes. This is claimed to have a number of advantages: lower bulk density, more rapid solution, and an unusually high capacity to absorb moisture before becoming wet. density, absolute Mass per unit volume of a substance; depends on temperature and pressure. For particulate matter it excludes the spaces that exist between particles, and measures only the density of the particles themselves; this is also known as solid or particulate density. See also density, bulk. density, bulk Mass per unit volume of particulate material, includ- ing spaces between the particles. See also density, absolute. density, particulate See density, absolute. dental ﬂuorosis Mottled dental enamel, see ﬂuoride. dental plaque See plaque (1). dent corn See maize. deodorisation The removal of an undesirable ﬂavour or odour. Fats are deodorised during reﬁning by bubbling superheated steam through the hot oil under vacuum, when most of the ﬂavoured substances are distilled off.
149 deoxycholic acid One of the secondary bile salts, formed by intestinal bacterial metabolism of cholic acid. deoxynivalenol Trichothecene mycotoxin produced when cereals are infected with Fusarium spp. 4-deoxypyridixine Antimetabolite of vitamin b6 used in experi- mental studies of vitamin B6 deﬁciency. deoxyribonucleic acid See dna; nucleic acids. deoxyuridine suppression test See dump suppression test. depectinisation The removal of pectin from fruit juice to produce a clear thin juice instead of a viscous, cloudy liquid, by enzymic hydrolysis. depositor Machine for depositing a precise amount of food into a mould or onto a conveyor belt. Derby English hard cheese, often ﬂavoured with sage. Derbyshire neck See goitre. dermatitis A lesion or inﬂammation of the skin caused by outside agents (unlike eczema, which is an endogenous disease); many nutritional deﬁciency diseases include more or less speciﬁc skin lesions (e.g. ariboﬂavinosis, kwashiorkor, pellagra, scurvy), but most cases of dermatitis are not associated with nutritional deﬁciency, and do not respond to nutritional supplements. Der- matitis herpetiformis is an uncommon itchy and blistering rash associated with coeliac disease. desferrioxamine Chelating agent used in treatment of iron over- load; the iron chelate is excreted in the urine. Given by 8–12 h subcutaneous perfusion 3–7 times a week. designer foods Alternative name for functional foods. desmosine The cross-linkage compound between chains of the connective tissue protein elastin, formed by reaction of two or three lysine residues in adjacent polypeptide chains. desmutagen Compound acting directly on a mutagen to decrease its mutagenicity. desorption Removal of moisture from a food. detox diets Weight reduction diets based on the (probably falla- cious) concept that the body accumulates large amounts of toxins from food and the environment that must be cleared by a period of fasting. detoxication The metabolism of (potentially) toxic compounds to yield less toxic derivatives that are more soluble in water and can be excreted in the urine or bile. A wide variety of ‘foreign com- pounds’ (i.e. compounds that are not normal metabolites in the body), sometimes referred to as xenobiotics, and some hormones and other normal body metabolites, are metabolised in the same way. See also cytochromes; phase i metabolism.
150 devils on horseback Bacon wrapped around stoned prunes, ske- wered with a toothpick and then grilled. See also angels on horseback. devitalised gluten See gluten. dewberry A hybrid fruit, a large variety of blackberry; rather than climbing, the plant trails on the ground. dew point The temperature at which a mixture of water vapour in air becomes saturated if cooled at constant absolute humidity, also known as saturation temperature. dexedrine Anorectic (appetite suppressing, see appetite control) drug formerly used in the treatment of obesity. dexfenﬂuramine See fenﬂuramine. dextrins A mixture of soluble compounds formed by the partial breakdown of starch by heat, acid or enzymes (amylases). Formed when bread is toasted. Nutritionally equivalent to starch; industrially used as adhesives, in the sizing of paper and textiles, and as gums. Limit dextrin is the product of enzymic hydrolysis of branched polysaccharides such as glycogen or amylopectin, when glu- cose units are removed one at a time until the branch point is reached, when the debranching enzyme is required for further hydrolysis. dextronic acid See gluconic acid. dextrose Alternative name for glucose. Commercially the term ‘glucose’ is often used to mean corn syrup (a mixture of glucose with other sugars and dextrins) and pure glucose is called dextrose. dextrose equivalent value (DE) A term used to indicate the degree of hydrolysis of starch into glucose syrup. It is the per- centage of the total solids that have been converted to reducing sugars; the higher the DE, the more sugars and fewer dextrins are present. Liquid glucoses are commercially available ranging from 2 DE to 65 DE. Complete acid hydrolysis converts all the starch into glucose but produces bitter degradation products. Glucose syrups above 55 DE are termed ‘high conversion’ (of starch); 35–55, regular conversion; below 20 the products of hydrolysis are maltins or maltodextrins. DFD See meat, dfd. DH UK Department of Health; web page http://www.dh.gov.uk/. DHA Docosohexaenoic acid, a long chain polyunsaturated fatty acid (C22:6 ω3). See ﬁsh oils. dhal Indian term for split peas of various kinds, e.g. the pigeon pea (Cajanus indicus), khesari (Lathyrus sativus); red dhal or Massur dhal is the lentil (Lens esculenta). dhanyia See coriander.
151 dhool The name given to leaves of tea up to the stage of drying. DHSS US Department of Health and Human Services; web site http://www.dhhs.gov/. dhupa See cocoa butter equivalents. diabetes Two distinct conditions: diabetes insipidus and diabetes mellitus. Diabetes insipidus is a metabolic disorder characterised by extreme thirst, excessive consumption of liquids and urina- tion, due to failure of secretion of the antidiuretic hormone. haemochromatosis is known as bronze diabetes. Diabetes mellitus is a metabolic disorder involving impaired metabolism of glucose due either to failure of secretion of the hormone insulin (Type I, insulin-dependent diabetes) or impaired responses of tissues to insulin (Type II, non-insulin- dependent diabetes). If untreated, the blood concentration of glucose rises to abnormally high levels (hyperglycaemia) after a meal and glucose is excreted in the urine (glucosuria). Prolonged hyperglycaemia may damage nerves, blood vessels and kidneys, and lead to development of cataracts, so effective control of blood glucose levels is important. Type I diabetes develops in childhood (sometimes called juve- nile-onset diabetes) and is due to failure to secrete insulin as a result of progressive auto-immune destruction of pancreatic β- islet cells.Treatment is by injection of insulin, either puriﬁed from beef or pig pancreas, now usually, biosynthetic human insulin, together with restriction of the intake of sugars. Type II diabetes generally arises in middle age (maturity- onset diabetes) and is due to insulin resistance of tissues; secretion of insulin by the pancreas is higher than normal in the early stages of the disease. It can sometimes be treated by restricting the consumption of sugars and reducing weight, or by the use of oral drugs which stimulate insulin secretion and/or enhance the insulin responsiveness of tissues (sulphonylureas and biguanides). It is also treated by injection of insulin to supplement secretion from the pancreas and overcome the resistance. Impairment of glucose tolerance similar to that seen in dia- betes mellitus sometimes occurs in late pregnancy, when it is known as gestational diabetes. Sometimes pregnancy is the stress that precipitates diabetes, and commonly the condition resolves when the child is born. Renal diabetes is the excretion of glucose in the urine without undue elevation of the blood glucose concentration. It is due to a reduction of the renal threshold, which allows the blood glucose to be excreted. See also glucokinase; metabolic syndrome; mody.
152 diabetic foods Loose term for foods that are specially formulated to be suitable for consumption by people with diabetes mellitus; generally low in sugars, and frequently containing sorbitol, xylulose or sugar derivatives that are slowly or incompletely absorbed. diacetyl Acetyl methyl carbonyl (CH3⋅CO⋅CO⋅CH3), the main ﬂavour in butter, formed during the ripening stage by the orga- nism Streptococcus lactis cremoris. Synthetic diacetyl is added to margarine as ‘butter ﬂavour’. diaﬁltration Dilution of the concentrate during reverse osmosis (see osmosis, reverse) or ultraﬁltration, to improve the recov- ery of solutes. dialysis A process for separating low MW solutes (e.g. salts and sugars) from larger ones (e.g. proteins) in solution. Small mole- cules can pass through a semipermeable membrane, while large molecules cannot. The membrane may be natural, such as pig bladder, or artiﬁcial, such as cellulose derivatives or collodion. diaminopimelic acid Intermediate in synthesis of lysine in bacte- ria; also important in sporulating bacteria for formation of spore coat. Mr 190.2, pKa 1.8, 2.2, 8.8, 9.9. diaphysis The shaft of a long bone. See also epiphysis; metaphysis. diarrhoea Frequent passage of loose watery stools, commonly the result of intestinal infection; rarely as a result of adverse reac- tion to foods or disaccharide intolerance. Severe diarrhoea in children can lead to dehydration and death; it is treated by feeding a solution of salt and sugar to replace ﬂuid and elec- trolyte losses. Osmotic diarrhoea is associated with retention of water in the bowel as a result of an accumulation of nonabsorbable water-soluble compounds; especially associated with excessive intake of sorbitol and mannitol. Also occurs in disaccharide intolerance. See also antimotility agents. diastase See amylases. diastatic activity A measure of the ability of ﬂour to produce maltose from its own starch by the action of its own amylase (diastase). This sugar is needed for the growth of the yeast during fermentation. See also amylograph. diazoxide 7-Chloro-3-methyl-1,2,4-benzothiadiazone 1,1-dioxide, used in treatment of chronic hypoglycaemia associated with excessive secretion of insulin due to pancreatic β-islet cell hyperplasia or cancer.
153 dichlorophenolindophenol (DCPIP) Purple-blue dye used in titrimetric assay of vitamin c; reduced to a colourless leuco dye by ascorbic acid, but not by dehydroascorbate, so does not measure total vitamin C. dicoumarol (dicoumarin, coumarin) Naturally occurring vitamin k antagonist, found in spoilt hay containing sweet clover (Melilo- tus alba or M. ofﬁcinalis); leads to haemorrhagic disease in cattle as a result of impaired synthesis of prothrombin and other vitamin K-dependent blood clotting proteins. dicyclomine See atropine. didronel Drug used to enhance bone mineralisation in women with post-menopausal osteoporosis. die A restricted opening at the discharge end of an extruder barrel. dielectric constant The ratio of the electrical capacitance of a food to the capacitance of air or vacuum under the same conditions. dielectric heating Similar principle to microwave heating but at lower frequencies. Food is passed between capacitor plates and high-frequency energy applied by using alternating electrostatic ﬁelds, which changes the orientation of the dipoles. The process is limited by the space between the plates; used for thawing blocks of frozen food, melting fats and drying biscuits. See also irradiation. dietary ﬁbre See ﬁbre, dietary. dietary folate equivalents (DFE) Method for calculating folic acid intake taking into account the lower availability of mixed folates in food compared with synthetic tetrahydrofolate used in food enrichment and supplements. 1 µg DFE = 1 µg food folate or 0.6 µg synthetic folate; total DFE = µg food folate + 1.7 × µg synthetic folate. dietary pattern analysis Statistical technique, based on cluster analysis, to analyse food consumption records in order to clas- sify the results into predeﬁned types of diet. Dietary Reference Intakes (DRI) US term for dietary refer- ence values. In addition to average requirement and rda, include tolerable upper levels (UL) of intake from supplements. See reference intakes. Dietary Reference Values (DRV) A UK set of standards for the amounts of each nutrient needed to maintain good health. See reference intakes. dietetic foods Foods prepared to meet the particular nutritional needs of people whose assimilation and metabolism of foods are modiﬁed, or for whom a particular effect is obtained by a con- trolled intake of foods or individual nutrients. They may be
154 formulated for people suffering from physiological disorders or for healthy people with additional needs. See also parnuts. dietetics The study or prescription of diets under special circum- stances (e.g. metabolic or other illness) and for special physio- logical needs such as pregnancy, growth, weight reduction. See also dietitian. diethylpropion Anorectic (appetite suppressant, see appetite control) drug with amphetamine-like action, formerly used in the treatment of obesity. diethyl pyrocarbonate A preservative for wines, soft drinks and fruit juice at a level of 50–300 ppm; it does not inhibit the growth of moulds. It breaks down within a few days to alcohol and carbon dioxide. Also known as pyrocarbonic acid diethyl, trade name Baycovin. diet-induced thermogenesis The increase in heat production by the body after eating. It is due to both the metabolic energy cost of digestion (the secretion of digestive enzymes, active transport of nutrients from the gut and gut motility) and the energy cost of forming tissue reserves of fat, glycogen and protein. It can be up to 10–15% of the energy intake. Also known as the speciﬁc dynamic action (SDA), luxus konsumption or thermic effect of foods. dietitian, dietician One who applies the principles of nutrition to the feeding of individuals and groups; plans menus and special diets; supervises the preparation and serving of meals; instructs in the principles of nutrition as applied to selection of foods. In UK the training and state registration of dietitians (i.e. legal per- mission to practise) is controlled by law. See also nutritionist. differential cell count See leucocytes. differential scanning calorimetery (DSC) Of fats; a small quan- tity of fat is slowly heated and compared with a reference sample at the same temperature. See also differential thermal analysis. differential thermal analysis (DTA) Of fats; a small quantity of fat is slowly heated and its temperature compared with a refer- ence sample. See also differential scanning calorimetery. digester See autoclave. digestibility The proportion of a foodstuff absorbed from the digestive tract into the bloodstream; normally 90–95%. It is mea- sured as the difference between intake and faecal output, with allowance being made for that part of the faeces that is not derived from undigested food residues (such as shed cells of the
155 intestinal tract, bacteria, residues of digestive juices). Digestibil- ity measured in this way is referred to as ‘true digestibility’, as distinct from the approximate measure ‘apparent digestibility’, which is simply the difference between intake and output. digestion The breakdown of a complex compound into its con- stituent parts, achieved either chemically or enzymically. Most frequently refers to the digestion of food, enzymic hydrolysis of proteins to amino acids, starch to glucose, fats to glycerol and fatty acids. See also gastrointestinal tract. digestive juices The secretions of the gastrointestinal tract that are involved in the digestion of foods: bile, gastric secre- tion, intestinal juice, pancreatic juice, saliva. digestive tract See gastrointestinal tract. diglycerides Glycerol esteriﬁed with two fatty acids; an inter- mediate in the digestion of triglycerides, and used as emulsi- ﬁers in food manufacture. dihydrochalcones See neohesperidin dihydrochalcone. dihydrostreptomycin Poorly absorbed antibiotic used in treat- ment of persistent bacterial diarrhoea and gastrointestinal infection. dilatant Food or other material that shows an increase in viscos- ity with increasing shear stress. See also pseudoplastic; rheopectic; thixotropic. dilatation of fats When fats melt from solids to liquid, at the same temperature, there is an increase in volume. Measurement of this increase, dilatometry, may be used to estimate the amount of solid fat present in a mixture at any given temperature. The precise measure is the difference between the volume of solid and liquid measured in millilitres per 25 g of fat. dilatometry See dilatation of fats. dill The aromatic herb Anethum graveolens (parsley family). The dried ripe seeds are used in pickles, sauces, etc. The young leaves (dill weed) are used, fresh, dried or frozen. dimethicone Antifoaming agent added to antacids to reduce ﬂatulence; used alone to treat gripe, colic and wind pain in infants. Also known as simethicone. dimethylpolysiloxane Antifoaming agent used in fats, oils and other foods. Also called methyl polysilicone or methyl silicone. dim-sum (dim-sim) Chinese; steamed dumplings and other delicacies. dinitroﬂuorobenzene See ﬂuorodinitrobenzene. dinitrophenol Reacts with the amino group of amino acids; used in separation of amino acids by thin-layer chromatography.Also a potent uncoupler of mitochondrial electron transport and
156 oxidative phosphorylation; was formerly used as a slimming agent. dinitrophenylhydrazine Reacts with many reducing sugars to form dinitrophenylhydrazones that have characteristic absorp- tion spectra and crystal shapes. Widely used for identiﬁcation of sugars before the development of modern chromatographic techniques. Also used for colorimetric determination of dehy- droascorbate and total vitamin c after oxidation to dehy- droascorbate using Cu2+ salts. dipeptidases Enzymes (EC 3.4.14.x) in the intestinal mucosal brush border that hydrolyse dipeptides to their constituent amino acids. dipeptide A peptide consisting of two amino acids. diphenoxylate See antidiarrhoeal agents; antimotility agents. diphenyl Also known as biphenyl (E-230), one of two compounds (the other is orthophenylphenol, OPP, E-231) used for the treat- ment of fruit after harvesting, to prevent the growth of mould. diphenylhydantoin Anticonvulsant used in treatment of epilepsy; inhibits absorption of folic acid and can lead to folate deﬁciency and megaloblastic anaemia. diphosphopyridine nucleotide (DPN) Obsolete name for nicoti- namide adenine dinucleotide, nad. diphyllobothriasis Intestinal infestation with the broad tapeworm Diphyllobothrium latum (ﬁsh tapeworm). Infection is from eating uncooked ﬁsh containing the larval stage. May cause vitamin b12 deﬁciency by impairing absorption. dipsa Foods that cause thirst. dipsesis (dipsosis) Extreme thirst, a craving for abnormal kinds of drinks. dipsetic Tending to produce thirst. dipsogen A thirst-provoking agent. dipsomania An imperative morbid craving for alcoholic drinks. direct extract See meat extract. disaccharidases Enzymes (EC 3.2.1.x) that hydrolyse disaccha- rides to their constituent monosaccharides in the intestinal mucosa: sucrase (also known as invertase) acts on sucrose and isomaltose, lactase on lactose, maltase on maltose and treha- lase on trehalose. disaccharide Sugars composed of two monosaccharide units; the nutritionally important disaccharides are sucrose, lactose, maltose and trehalose. See also carbohydrate. disaccharide intolerance Impaired ability to digest lactose, maltose or sucrose, owing to lack of lactase, maltase or sucrase in the small intestinal mucosa. The undigested sugars remain in
157 the intestinal contents, and are fermented by bacteria in the large intestine, resulting in painful, explosive, watery diarrhoea. Treatment is by omitting the offending sugar from the diet. Lack of all three enzymes is generally caused by intestinal infections, and the enzymes gradually recover after the infection has been cured. Lack of just one of the enzymes, and hence intol- erance of just one of the disaccharides, is normally an inherited condition. Lactose intolerance due to loss of lactase is normal in most ethnic groups after puberty. disc mill Machine for comminution of dry foods. In a single disc mill the food passes between a stationary casing and a rotating grooved disc; a double disc mill achieves greater shearing force by using two grooved discs rotating in opposite directions. Pin and disc mills have a single or double grooved discs with inter- meshing pins to provide additional shear and impact force. disodium guanylate, disodium inosinate Sodium salts of the purines, guanylic and inosinic acids, used as ﬂavour enhancers, frequently together with monosodium glutamate. dispersed phase Droplets in an emulsion. dispersibility The ease with which powder particles become dis- tributed through a liquid. Powders with good wettability and sinkability have good dispersibility. displacement analysis See radioimmunoassay. distillers’ dried solubles See spent wash. DIT See diet-induced thermogenesis. diuresis Increased production and excretion of urine; it occurs in diseases such as diabetes, and also in response to diuretics. diuretics Substances that increase the production and excretion of urine. They may be either compounds that occur naturally in foods (including caffeine and alcohol) or may be drugs used clinically to reduce the volume of body ﬂuid (e.g. in the treat- ment of hypertension and oedema). diverticular disease Diverticulosis is the presence of pouch-like hernias (diverticula) through the muscle layer of the colon, asso- ciated with a low intake of dietary ﬁbre and high intestinal pres- sure due to straining during defecation. Faecal matter can be trapped in these diverticula, making them inﬂamed, causing pain and diarrhoea, the condition of diverticulitis. See also gastrointestinal tract. djenkolic acid A sulphur-containing amino acid found in the djenkol bean, Pithecolobium lobatum, which grows in parts of Sumatra. It is a derivative of cysteine, and is metabolised but, being relatively insoluble, unmetabolised djenkolic acid crys- tallises in the kidney tubules.
158 DNA Deoxyribonucleic acid, the genetic material in the nuclei of all cells. A polymer of deoxyribonucleotides, the purine bases adenine and guanine, and the pyrimidine bases thymidine and cytidine, linked to deoxyribose phosphate. The sugar-phosphates form a double stranded helix, with the bases paired internally. See also nucleic acids. DNA cloning The process of inserting the DNA containing one or more genes into a plasmid or a bacterial virus and then growing these in bacterial (or yeast) cells. dockage Name given to foreign material in wheat which can be removed readily by a simple cleaning procedure. docosanoids Long-chain polyunsaturated fatty acids with 22 carbon atoms. docosohexaenoic acid A long-chain polyunsaturated fatty acid (C22:6 ω3); see ﬁsh oils. docusates See laxative. dogﬁsh A cartilaginous ﬁsh, Scilliorinus caniculum, or Squalis acanthias, related to the sharks; sometimes called rock salmon or rock eel. dolomite Calcium magnesium carbonate. dolphin ﬁsh Large marine ﬁsh (about 2 m long); common dolphin ﬁsh is Coryphaena hippurus, pompano dolphin ﬁsh is C. equiselis. Both are commonly marketed as mahi-mahi. Composition/100 g: water 78 g, 356 kJ (85 kcal), protein 18.5 g, fat 0.7 g, cholesterol 73 mg, carbohydrate 0 g, ash 2.1 g, Ca 15 mg, Fe 1.1 mg, Mg 30 mg, P 143 mg, K 416 mg, Na 88 mg, Zn 0.5 mg, Se 36.5 µg, vitamin A 54 µg retinol, B1 0.02 mg, B2 0.07 mg, niacin 6.1 mg, B6 0.4 mg, folate 5 µg, B12 0.6 µg, pantothenate 0.8 mg. A 100 g serving is a source of P, pantothenate, a good source of vitamin B6, a rich source of Se, niacin, vitamin B12. Do-MakerTM process For continuous breadmaking. Ingredients are automatically fed into continuous dough mixer, the yeast sus- pension being added in a very active state. domperidone dopamine antagonist, stimulates gastric emptying and small intestinal transit; strengthens contraction of the oesophageal sphincter. Used in treatment of dyspepsia and oesophageal reﬂux. döner kebab See kebab. dopa 3,4-Dihydroxyphenylalanine; a non-protein amino acid, precursor of dopamine, noradrenaline and adrenaline. Mr 197.2, pKa 2.32, 8.72, 9.96, 11.79. dopamine 3,4-Dihydroxyphenylethylamine; a neurotransmitter, and also precursor of noradrenaline and adrenaline. dormers Victorian; chopped cooked lamb mixed with rice and suet, rolled into sausage shapes, coated in egg and breadcrumbs and fried.
159 dosa Indian; shallow-fried pancake made from a mixture of rice and a legume; the dough is left to undergo bacterial fermentation before cooking. The principal bacteria involved are Leuconostoc mesenteroides and Streptococcus faecalis, introduced with a starter of an earlier batch of fermented dough. dose–response assessment The relationship between the magni- tude of exposure to a (potential) toxin and the probability of adverse effects. dosimeter Instrument to measure the dose of irradiation received by a food. double Gloucester English hard cheese. double-labelled water Dual isotopically labelled water, contain- ing both deuterium (2H) and 18O (i.e. 2H218O), used in studies of energy balance. 2H is lost from the body only as water, while 18O is lost as both water and carbon dioxide; the difference in rate of loss of the two isotopes from body water permits estimation of total carbon dioxide production, and hence energy expenditure, over a period of 7–14 days. See also calorimetry; isotopes. dough cakes A general term to include crumpets, mufﬁns and pikelets, all made from ﬂour, water and milk. The batter is raised with yeast and baked on a hot plate or griddle (hence sometimes known as griddle cakes). Crumpets have sodium bicarbonate added to the batter; mufﬁns are thick and well aerated, less tough than crumpets; pikelets are made from thinned crumpet batter. doughnuts Deep fried rings of cake dough or yeast-leavened dough. dough strengtheners Compounds used to modify starch and gluten, to produce a more stable dough. Douglas bag An inﬂatable bag for collecting expired air to measure the consumption of oxygen and production of carbon dioxide, for the measurement of energy expenditure by indirect calorimetry. See also spirometer. Dowex An ion-exchange resin. DPN (diphosphopyridine nucleotide) Obsolete name for nicoti- namide adenine dinucleotide. See nad. dragée French; whole nuts with hard sugar or sugared chocolate coating. Silver dragées are coated with silver leaf. dried solubles, distiller’s See spent wash. dripping Unbleached and untreated fat from the adipose tissue or bones of sheep or oxen. Also the rendered fat that drips from meat as it is roasted. drisheen Irish; blood pudding. See black pudding. dropsy Popular name for oedema.
160 drupe Botanical term for a ﬂeshy fruit with a single stone enclos- ing the seed that does not split along deﬁned lines to liberate the seed, e.g. apricot, cherry, date, mango, olive, peach, plum. DRV Dietary Reference Values. See reference intakes. dry–blanch–dry process A method of drying fruit so as to retain the colour and ﬂavour; it is faster than drying in the sun and pre- serves ﬂavour and colour better than hot air drying. The mater- ial is dried to 50% water at about 82 °C, blanched for a few minutes, then dried at 68 °C over a period of 6–24 h to 15–20% water content. dryeration A method used for drying cereal grains which involves an initial drying stage, using heated air, followed by a holding period and ﬁnal drying in ambient air; relieves the stresses set up in the grain during the initial drying and reduces its brittleness compared with grain dried by conventional methods. dry frying Frying without the use of fat by using an antistick agent (silicone or a vegetable extract). dry ice Solid carbon dioxide, used to refrigerate foodstuffs in transit and for carbonation of liquids. It sublimes from the solid to a gas (without liquefying) at −79 °C. drying agents Hygroscopic compounds used to absorb moisture and maintain a low humidity environment. drying, azeotropic A method of drying food by adding a solvent that forms a low-boiling-point mixture (azeotrope) with water, which can be removed under vacuum. drying oil Any highly unsaturated oil that absorbs oxygen and, when in thin ﬁlms, polymerises to form a skin. Linseed and tung oil are examples of drying oils used in paints and in the manu- facture of linoleum, etc. Nutritionally they are similar to edible oils, but toxic when polymerised. See also iodine number. dry weight basis (dwb) The composition of a wet food based on the mass of dry solids it contains. DSC See differential scanning calorimetery. DTA See differential thermal analysis. Dublin Bay prawn Scampi or Norway lobster; a shellﬁsh. Nephrops norvegicus. See lobster. du Bois formula A formula for calculating body surface area. duck Water fowl, Anas spp.; wild duck is mallard (A. platyrhynchos). Composition/100 g: (edible portion 34%) water 74 g, 553 kJ (132 kcal), protein 18.3 g, fat 5.9 g (of which 50% saturated, 33% mono-unsaturated, 17% polyunsaturated), cholesterol 77 mg, carbohydrate 0 g, ash 1.1 g, Ca 11 mg, Fe 2.4 mg, Mg 19 mg, P 203 mg, K 271 mg, Na 74 mg, Zn 1.9 mg, Cu 0.3 mg, Se 13.9 µg,
161 vitamin A 24 µg retinol, E 0.7 mg, K 2.8 mg, B1 0.36 mg, B2 0.45 mg, niacin 5.3 mg, B6 0.34 mg, folate 25 µg, B12 0.4 µg, pan- tothenate 1.6 mg, C 6 mg. A 100 g serving is a source of Fe, Se, Zn, vitamin B6, folate, a good source of Cu, P, vitamin B1, B2, niacin, pantothenate, a rich source of vitamin B12. ductless glands See endocrine glands. dulcin A synthetic material (p-phenetylurea or p-phenetolcar- bamide, discovered in 1883) which is 250 times as sweet as sugar but is not permitted in foods. Also called sucrol and valzin. dulcitol A six-carbon sugar alcohol which occurs in some plants and is formed by the reduction of galactose; also known as melampyrin, dulcite or galacticol. dulse Edible purplish-brown seaweeds, Rhodymenia palmata and Dilsea carnosa, used in soups and jellies. dUMP suppression test Deoxyuridine suppression test, for folate and vitamin b12 status. Preincubation of rapidly dividing cells with dUMP leads to a large intracellular pool of newly syn- thesised TMP (thymidine monophosphate), and hence little of the added [3H]TMP is incorporated into DNA. In deﬁciency of either vitamin there is little endogenous synthesis of TMP and hence more incorporation of [3H]TMP. In folate deﬁciency addition of any form of folic acid will restore the suppression of incorporation of [3H]TMP by dUMP, but vitamin B12 will have no effect. In vitamin B12 deﬁciency, addition of vitamin B12 or any one-carbon folate derivative other than methyl folate will be effective. dun Brown discoloration in salted ﬁsh caused by mould growth. Dunaliella bardawil A red marine alga discovered in 1980 in Israel, which is extremely rich in β-carotene, containing 100 times more than most other natural sources. Dunlop Scottish cheddar-type cheese. dunst Very ﬁne semolina (starch from the endosperm of the wheat grain) approaching the ﬁneness of ﬂour. Also called break middlings (not to be confused with middlings, which is branny offal). duocrinin Peptide hormone secreted by the duodenum; increases intestinal secretion and absorption. duodenal ulcer See ulcer. duodenum First part of the small intestine, between the stomach and the jejunum; the major site of digestion. Pancreatic juice and bile are secreted into the duodenum. So-called because it is about 12 ﬁnger breadths in length. See also gastrointestinal tract. durian Fruit of tree Durio zibethinum, grown in Malaysia and Indonesia. Each fruit weighs 2–3 kg and has a soft, cream-
162 coloured pulp, with a smell considered disgusting by the uninitiated. Composition/100 g: (edible portion 32%) water 65 g, 615 kJ (147 kcal), protein 1.5 g, fat 5.3 g, carbohydrate 27.1 g, ﬁbre 3.8 g, ash 1.1 g, Ca 6 mg, Fe 0.4 mg, Mg 30 mg, P 39 mg, K 436 mg, Na 2 mg, Zn 0.3 mg, Cu 0.2 mg, Mn 0.3 mg, vitamin A 2 µg RE (29 µg carotenoids), B1 0.37 mg, B2 0.2 mg, niacin 1.1 mg, B6 0.32 mg, folate 36 µg, pantothenate 0.2 mg, C 20 mg. A 150 g serving (quarter fruit) is a source of Mg, Mn, vitamin B2, a good source of Cu, vitamin B6, folate, a rich source of vitamin B1, C. durum wheat A hard type of wheat, Triticum durum (most bread wheats are T. vulgare); mainly used for the production of semolina for preparation of pasta. Dutching See cocoa, dutch. Dutch oven A semicircular metal shield which may be placed close to an open ﬁre; ﬁtted with shelves on which food is roasted. It may also be clamped to the ﬁre bars. D value See decimal reduction time. dwb See dry weight basis. DynabeadsTM Magnetic microspheres coated with antibodies, used in immunomagnetic separation. DyoxTM Chlorine dioxide used to treat ﬂour, see ageing. dysentery Infection of the intestinal tract causing severe diar- rhoea with blood and mucus. Amoebic dysentery is caused by Entamoeba histolytica, and occasionally other protozoans spread by contaminated food and water. Symptoms may develop many months after infection. Bacillary dysentery is caused by Shigella spp.; symptoms develop 1–6 days after infection. dysgeusia Distortion of the sense of taste, a common side-effect of some drugs. See also gustin; hypogeusia; parageusia. dyspepsia Any pain or discomfort associated with eating; may be a symptom of gastritis, peptic ulcer, gall-bladder disease, etc.; functional dyspepsia occurs when there is no obvious structural change in the intestinal tract. Treatment includes a bland diet. See also indigestion. dysphagia Difﬁculty in swallowing, commonly associated with disorders of the oesophagus. Inability to swallow is aphagia. E e On food labels, before the weight or volume, to indicate that this has been notiﬁed to the regulatory authorities of the EU as a standard package size.