Benders'dictionary of nutrition and food technology

429thyroxine deiodinase (EC 3.8.1.4).Through its role in glutathioneperoxidase it acts as an antioxidant, and to some extent cancompensate for vitamin e deficiency. Similarly, vitamin E cancompensate for selenium deficiency to some extent.Requirements are of the order of 50 µg/day; in parts of NewZealand, Finland and China soils are especially poor in seleniumand deficiency occurs. In China, selenium deficiency is associatedwith keshan disease and kashin–beck syndrome.Selenium is toxic in excess; mild selenium intoxication resultsin production of foul-smelling hydrogen selenide, which isexcreted on the breath and through the skin. Intakes above200µg/day are considered hazardous.See also thyroid hormones.Selenium-ACE TM Yeast-based product providing selenium andvitamins a, c and e.selenocysteine The selenium analogue of the amino acid cysteine.Incorporated during ribosomal protein synthesis, andformed as a result of the action of selenocysteine synthetase(EC 2.9.1.1) on serine bound to tRNA. The codon for selenocysteineis UGA, one of the stop codons, read in a contextsensitivemanner in an untranslated stem-loop sequence of themRNA.seltzer Effervescent mineral water, originally from Niederselters,Germany.See also soda water.seminose See mannose.semipermeable membrane A membrane with pores that permitthe passage of small molecules, but not larger molecules such asproteins. Used in dialysis and ultrafiltration.semolina The inner, granular, starchy endosperm of hard ordurum wheat (not yet ground into flour); used to make pasta anda milk pudding.Composition/100 g: water 12.7 g, 1507 kJ (360 kcal), protein12.7g, fat 1g, carbohydrate 72.8g, fibre 3.9g, ash 0.8g, Ca 17mg,Fe 1.2 mg, Mg 47 mg, P 136 mg, K 186 mg, Na 1 mg, Zn 1 mg, Cu0.2 mg, Mn 0.6 mg, vitamin B 1 0.28 mg, B 2 0.08 mg, niacin 3.3 mg,B 6 0.1 mg, folate 72 µg, pantothenate 0.6 mg.senna Dried fruits of Cassia spp., used as an irritant laxative.sensitivity Of an assay; the smallest amount that can be determinedwith acceptable precision.sensory properties See organoleptic.sequestrants Compounds that form soluble complexes with polyvalentmetal ions, preventing them from undergoing reactions,and so improving the quality and stability of the product.