Benders'dictionary of nutrition and food technology

260isopropyl citrate Ester of isopropyl alcohol and citric acid, usedto chelate metal ions that might otherwise cause rancidity in oils.See chelating agents.isostatic Uniform pressure throughout a food or other material.isosyrups See syrups, high fructose.isothermal Processes in which the temperature is held constantand volume varies with pressure.See also adiabatic; isobaric.isotonic Solutions with the same osmotic pressure (concentrationof solutes); often refers to a solution with the same osmoticpressure as body fluids. Hypertonic and hypotonic refer to solutionsthat are respectively more and less concentrated.isotopes Forms of elements with the same chemical properties,differing in atomic mass because of differing numbers of neutronsin the nucleus. Thus, hydrogen has three isotopes, of atomicmasses 1, 2 and 3, generally written as 1 H (the most abundantisotope of hydrogen), 2 H (deuterium) and 3 H (tritium). Theincorporation of isotopes into compounds (labelled compoundsor tracers) permits the metabolic fates of those compounds inthe body to be followed easily.Stable isotopes can be detected only by their atomic mass.Since they emit no radiation, they are considered completely safefor use in labelled compounds given to human beings. Examplesof stable isotopes commonly used in nutrition research include2H, 13 C, 15 N and 18 O.Unstable isotopes decay to stable elements, emitting radiationin the process. This may be α-particles, β-radiation (electrons),γ-radiation or X-rays, depending on the particular isotope.Radioactive isotopes can readily be detected by the radiationemitted. The time taken for half the radioactive isotope to decayis the half-life (2) of the isotope, and can vary from a fractionof a second, through several days to years (e.g. the half-life of 3 His 12.5 years, that of 14 C is 5200 years).isotretinoin 13-Cis retinoic acid, a retinoid used in the treatmentof severe acne.isozymes See isoenzymes.ispaghula Polysaccharide gum derived from the seed husksof Plantago ovata. Used as a thickening agent in foods and as alaxative.itai-itai disease See cadmium.iu See international units.IUFoST International Union of Food Science and Technology;web site http://www.iufost.org/.IUNS International Union of Nutritional Sciences; web sitehttp://www.iuns.org/.