Factors which facilitate inactivation of quercetin mutagenicity.

Oxygen, oxidizing enzymes such as polyphenol oxidase (tyrosinase) and alkaline pH, irreversibly inactivate the mutagenicity of quercetin in the Ames test. The loss of mutagenic activity correlates with decreases in the ultraviolet absorption maximum of quercetin near 370 nm. The extent of inactivation increases with time but apparently not significantly with temperature of exposure, and decreases with quercetin concentration. Metal salts such as ferrous and copper sulfates also facilitate inactivation, but these effects may be reversible. Understanding the factors which minimize the mutagenic potential of food ingredients should lead to safer foods.