Antioxidant activity of some brown pigments in<span style="font-variant:small-caps">l</span> -ascorbic acid solutions

The inhibition effects of the brown pigments produced by reaction of glyoxal with glycine or ethyl amine and by self-condensation of diacetyl on<span style="font-variant:small-caps">l</span> -ascorbic acid oxidation catalized by bivalent copper were studied. The relative inhibition constants of the pigments were 150 and 110 for the glyoxal-glycine pigments, 70 for the glyoxal-ethylamine pigment and 20 ml/g · min for the diacetyl pigment. More polar pigments had better antioxidative activity in solutions of<span style="font-variant:small-caps">l</span> -scorbic acid, while less polar pigments were more effective in protecting lipids against autoxidation.