Thermolabile

Thermolabile, unstable with respect to heating; a term used to denote the property of various substances to easily decompose when heated by 1°. In contrast, substances that are stable to heating are designated as thermostable (heat-resistant). These same terms are often applied to microorganisms, especially their spores, as well as to plant seeds. Both concepts have extremely relative value and merely indicate greater or lesser resistance to heating of a given substance only in comparison with other substances of the same group. For example, vitamin C is called thermolabile as a substance that decomposes at a comparatively lower temperature than a number of other vitamins. Alexin (complement) is distinguished by its thermolability, which allows it to be separated from ambceptor, which withstands higher temperatures. The properties of thermolability and thermostability are not constant and depend on a number of conditions. For example, vitamin A is thermolabile when heated while simultaneously passing a stream of air, but when air is excluded, it can withstand temperatures up to 120°. The presence of water is also of great importance in terms of thermolability (rapid denaturation of proteins when heated in water and their stability in dry form), as well as the presence of various chemical substances.