Antioxydants naturels végétaux

Abstract

Oxidation of lipids corresponds to the degradation of fatty acids by a continuation of sequential reactions : the decomposition of peroxides formed on the fatty chains after the attack by radicalaires compounds ends in the production of aldéhydes, cétones, acids, alcohols and go to a loss of the organoleptic and nutritional qualities (characteristic rancy smell and taste), thus a significant loss of economic value. The synthetic antioxidants (BHT, BHA) are effective, but their use is of pleased in more controversial. It is thus advisable to study with attention the plant natural antioxidants. The antioxidizing properties of the plant products are given by a certain number of tests as the test to the DPPH or the test ORAC in aqueous environment, and the measure of the index of peroxides or the Rancimat for the lipophilic phases. Certain tests are above all models of study, and few are really recognized, however certain standards are outlined, and the standardization arrives finally (cf the test ORAC, reference USDA). Among the compound vegetables which stand out very sharply at the level of their antioxidizing property, polyphénols are the most represented in the vegetal reign. It is a very wide family, but the extracts of grape seeds or tea are now well identified, and present results in the fight against the oxidation completely surprising.