Evaluation and Analysis of Key Flavor and Warmed-over Flavor of Pre-prepared Steamed Pork with Preserved Vegetable Based on HS-SPME-GC-MS Combined with Electronic Tongue

In order to study the key flavor characteristics and the influence of oxidation degree of oil on warmed-over flavor of pre-prepared steamed pork with preserved vegetable. The volatile flavor compounds and taste indexes of different brands of pre-prepared steamed pork with preserved vegetable were quantitatively detected by headspace-solid phase microextraction-gas chromatography-mass spectrometry and electronic tongue. The key flavor factors of pre-prepared steamed pork with preserved vegetable were screened and analyzed by odor activity value (OAV) and principal component analysis. Acid value, peroxide value and TBA value were used to analyze the oxidation degree of oil and warmed-over flavor of different brands of pre-prepared steamed pork with preserved vegetable. Results showed that a total of 85 volatile compounds were identified from 7 kinds of pre-prepared steamed pork with preserved vegetable, including 16 alkanes, 19 terpenes, 7 alcohols, 22 aldehydes, 3 ketones, 13 esters, 3 phenols and 2 others. A total of 23 key volatile compounds were screened by OAV, and the substances with OAV>10 were 1-octene-3-ol, hexanal, heptanal, octanal, nonanal, (E,E)-2,4-nonadienal, capric aldehyde, (E)-2-decenal, (E,E)-2,4-decenal and 1-octene-3-ketone, which were the key flavor substances for pre-prepared steamed pork with preserved vegetable. The results of electronic tongue and overripe taste evaluation showed that the taste of 7 kinds of pre-prepared steamed pork with preserved vegetable were mainly salty, umami and aftertaste. Its overripe taste mainly presented linseed oil taste and rancidity taste. The oil oxidation indexes of 7 kinds of pre-prepared steamed pork with preserved vegetable were higher and the differences were significant (P<0.05). The correlation analysis showed that the main factors that produce warmed-over flavor were (E)-2-decenal, 2-heptanone, nonylaldehyde, 1-octene-3-ketone, (E,E)-2,4-decenal, hexal, pentaldehyde, heptanal, (E)-2-heptenal and octanal, which were positively correlated with acid value, peroxide value and TBA value. In summary, the key flavor factors of the 7 kinds of pre-prepared steamed pork with preserved vegetable were related to overcooked taste, and it was speculated that the overcooked taste of pre-prepared steamed pork with preserved vegetable was related to the higher oxidation degree of oil. The key flavor factors, electronic tongue and overripe taste evaluation indexes obtained in this study provide the basis for the establishment of flavor quality system and overripe taste control of pre-prepared steamed pork with preserved vegetable.