Research on flavor characteristics of beef cooked in tomato sour soup by gas chromatography-ion mobility spectrometry and electronic nose

Tomato sour soup beef (TSSB), which is beef cooked with tomato sour soup (TSS), is nutritious and tastes "meaty and sour", however, effect on beef flavor characteristics at the molecular level remains unclear. Gas chromatography-ion mobility spectrometry (GC-IMS), in combination with an electronic nose, was used to determine flavor differences with cooking time. A total of 74 volatile flavor compounds (VFCs) was identified by GC-IMS. In TSSB, relative contents of esters, alcohols, ketones and acids increased, whereas aldehydes decreased, relative to control cooked beef. E-nose analysis found differences in aroma characteristics of TSSB at different stages of cooking. Sensory analysis showed that TSSB had improved taste and flavor. A total of 24 VFCs was identified by orthogonal partial least squares discriminant analysis (OPLS-DA), of which 2-methyl propionate ethyl ester, isoamyl acetate, isobutyl butanoate, isoamyl butanoate, propionate, benzaldehyde and 2-butanone (D) were the characteristic VFCs of TSSB. Correlation analysis indicated that lactic, citric and succinic acids were positively correlated with ethyl 2-methylpropanoate, isoamyl acetate, isopentyl butanoate, isobutyl butanoate, benzaldehyde and 2-butanone (D). Cooking beef in TSS decreased the relative content of aldehydes and increased that of esters, alcohols, ketones and acids, further improving the flavor and sensory quality of the beef.