Benders'dictionary of nutrition and food technology

148from either dehydration or freezing alone, and rehydration ismore rapid than with dehydrated products.dehydroretinol An analogue of vitamin a found in freshwaterfish, which has about half the biological activity of retinol.Formerlytermed vitamin A 2 .Delaney Amendment Clause in the US Federal Food, Drug andCosmetic Act (1958) which states that no food additive shall bedeemed safe (and therefore may not be used) after it is found toinduce cancer when ingested by man or animals, at any doselevel.delayed hypersensitivity An adverse reaction to food, occurringseveral hours after ingestion, caused by cell-mediated immuneresponses (activated lymphocytes) as opposed to immunoglobulin-mediatedresponses, which occur rapidly.See also coeliac disease.demerara sugar See sugar.denaturation A normally irreversible change in the structure ofprotein by heat, acid, alkali or other agents which results in lossof solubility and coagulation. Denatured proteins lose biologicalactivity (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, withthe crystals branched or star-like (dendritic) instead of thenormal cubes. This is claimed to have a number of advantages:lower bulk density, more rapid solution, and an unusually highcapacity to absorb moisture before becoming wet.density, absolute Mass per unit volume of a substance; dependson temperature and pressure. For particulate matter it excludesthe spaces that exist between particles, and measures only thedensity of the particles themselves; this is also known as solid orparticulate density.See also density, bulk.density, bulk Mass per unit volume of particulate material, includingspaces 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 superheatedsteam through the hot oil under vacuum, when most of theflavoured substances are distilled off.