Abstract: Sensory evaluation, gas chromatography-ion mobility spectrometry (GC-IMS) and chemometrics were applied to analyze the change of volatile flavor compounds in Pixian bean paste during cooking. The results indicated that Pixian bean paste showed the strongest fruity aroma after four minutes of stir frying, and strongest woody, nutty and burnt aromas after five minutes. As the stir-frying time increased, the spicy aroma of Pixian bean paste was weakened. The volatile components of Pixian bean paste with different stir-frying times were well separated by GC-IMS and a total of 97 volatile components were detected at five stir-frying times, aldehydes, ketones and esters being the major ones. The relative contents of aldehydes and esters increased as the stir-frying time prolonged, including butanal, isobutenal, 2-methylpropanal, valental, 3-methylbutanal, isobutyl butyrate, ethyl butyrate and methyl acetate. Totally 34 signature volatile components were identified by orthogonal partial least squares-discriminant analysis (OPLS-DA). Pearson correlation analysis showed that the woody, nutty and burnt aromas were strongly negatively correlated with the concentrations of most aroma compounds. The spicy aroma was strongly positively correlated with the concentrations of most aroma components.

Key words: Pixian bean paste; stir-frying time; gas chromatography-ion mobility spectrometry; volatile flavor compounds