Benders'dictionary of nutrition and food technology

466taste The tongue can distinguish five separate tastes: sweet, salt,sour (or acid), bitter and savoury (sometimes called umami, fromthe Japanese word for a savoury flavour), owing to stimulationof the taste buds.The overall taste or flavour of foods is due tothese tastes, together with astringency in the mouth, texture andaroma.The tongue can also detect polyunsaturated fatty acidsreleased from dietary triacylglycerol by lipase secreted by thetongue.taste buds Situated mostly on the tongue; about 9000 elongatedcells ending in minute hair-like processes, the gustatory hairs.Taste buds for salt have a sodium ion channel in the cell membrane,for sourness a proton channel and for umami a glutamatechannel; taste buds for sweetness and bitterness have cell surfacereceptors that lead to production of intracellular secondmessengers.tatare (steak tatare) Dish prepared from minced beef or othermeat, eaten uncooked.taurine Aminoethane sulphonic acid, derived from cysteine byoxidation of the sulphydryl group and decarboxylation. Knownto be a dietary essential for cats (deficient kittens are blind) andpossibly essential for human beings, since the capacity for synthesisis limited, although deficiency has never been observed. Itsmain functions are in conjugation of bile acids, and maintenanceof osmotic integrity in tissues, especially the retina.taurochenodeoxycholic acid The taurine conjugate of chenodeoxycholicacid, see bile.taurocholic acid The taurine conjugate of cholic acid, see bile.TBARS (thiobarbituric acid reactive substances) Colorimetricmethod of determination of dialdehydes formed by breakdownof lipid peroxides, by reaction with thiobarbituric acid; used asan index of radical attack on unsaturated fatty acids, and henceas an inverse index of antioxidant status.TBA value A measure of oxidative rancidity in fats. Thiobarbituricacid reacts with malondialdehyde formed by oxidation ofpolyunsaturated fatty acids to form a coloured product.TDT thermal death time.tea A beverage prepared by infusion of the young leaves, leafbuds and internodes of varieties of Camellia sinensis and C.assamica, originating from China. Green tea is dried withoutfurther treatment. Black tea is fermented (actually an oxidation)before drying; Oolong tea is lightly fermented. Among the blackteas, flowering Pekoe is made from the top leaf buds, orangePekoe from first opened leaf, Pekoe from third leaves, andSouchong from next leaves. Earl Grey is flavoured with