MUTAGEN FORMATION IN HEATED WHEAT GLUTEN, CARBOHYDRATES, AND GLUTEN CARBOHYDRATE BLENDS

Gluten, carbohydrates, and gluten/carbohydrate blends were heated in a simulation of low-moisture baking and assayed by the Ames Salmonella his-reversion test in order to evaluate the formation of mutagenic browning products. An aqueous acetonitrile extract of heated gluten was highly mutagenic when assayed with Salmonella typhimurium strain TA98 with metabolic activation. Weak mutagenicity was also observed with strains TA100 and TA102. Gluten heated in a vacuum oven yielded less extract than did the air-baked protein, but its mutagenic activity (revertants per milligram of extract) was similar. Baked D-glucose, maltose, lactose, sucrose, wheat starch, potato amylose, cellulose, microcrystalline hydrocellulose, sodium ascorbate and L-ascorbic acid, sodium (carboxymethyl)cellulose, or [(hydroxypropyl)methyl] cellulose were moderately mutagenic in strain TA98 with microsomal (S9) activation and were weakly mutagenic without microsomal activation in strains TA100, TA102, and TA1537. Heated blends of gluten with 20% of these carbohydrates were also mutagenic, but the total activity recovered did not exceed levels of the individual ingredients baked separately. Maillard-type melanoidins prepared from L-lysine and D-fructose were very weakly active with strain TA98 but were mutagenic without S9 activation in strains TA100, TA102, and TA2637. Possible sources of mutagens, the significance of these findings for food safety, and possible approaches to minimize mutagen formation are discussed. © 1990, American Chemical Society. All rights reserved.