Quality characteristics and volatile flavor compounds of sufu during the pre-fermentation process

In this study, the changes of physiochemical indexes, color parameters, texture parameters and volatile flavor substances of sufu during the pre-fermentation process (0-5 d) were investigated by conventional detection methods, colorimeter, texture analyzer and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology, and correlation analysis of the key volatile flavor substances and quality indexes of sufu samples after prefermentation was conducted. The results showed that the moisture first decreased and then stabilized, while the contents of total acid, amino acid nitrogen and water-soluble protein as a whole first increased and then decreased during the pre-fermentation process. The L^* value and a^* value generally showed a downward trend, while the b^* value generally showed an upward trend, and the color difference value ΔE changed relatively little. The hardness, cohesion and adhesiveness all showed a trend of first increasing and then decreasing, while the elasticity change trend was the opposite. A total of 71 volatile flavor substances were detected, based on the odor activity value (OAV), a total of 15 key volatile flavor substances (OAV≥1) and 8 characteristic volatile flavor substances (OAV≥50) were screened. Correlation analysis indicated that the 6 volatile flavor substances such as isovaleric acid, dimethyltrisulfide, isopentaldehyde, trimethylamine, dimethyl disulfide and isopentanol were significantly or extremely significantly positively correlated with physicochemical indicators, color and texture parameters (P<0.05, P<0.01).