A pyrolysate that exhibited mutagenic activity toward Salmonella typhimurium TA98 and TA100 from the pyrolytic products of soybean globulin. 2-Amino-9H-pyrido[2,3-b]indole (AαC) and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) are two mutagenic and carcinogenic heterocyclic amines formed during ordinary cooking.