A source of error in mutagen testing of foods.

Mutagenic compounds reported to be present in foods may be forming during the extraction process rather than during cooking or baking. In this study, the formation of mutagenic substances in biscuits was examined using in the extraction procedure either ammonium sulfate and ammonium hydroxide or sodium sulfate and sodium hydroxide. Compounds producing high mutagenic activity in Salmonella strains 1538 and TA 98 obtained from aqueous biscuit extracts containing ammonium ions. No mutagenic activity was observed in extracts from aqueous biscuit extracts containing sodium ions until some ammonium ions (NH4OH) were added. We suggest that ammonium sulfate and ammonium hydroxide not be used in the extraction procedure of food when studying mutagen formation.