GC-MS Combined with Chemometrics for Characterizing the Effect of Staphylococcus saprophytic MF B8 on Volatile Flavor Compounds in Stinky Mandarin Fish

To investigate the effect of Staphylococcus saprophyticus MF B8 from stinky mandarin fish on the volatile flavor of stinky mandarin fish, four experimental groups were set up using mandarin fish as raw material: fresh mandarin fish (S1), uninoculated fermentation (S2), inoculated fermentation by adding 1% MF B8 (S3) and 2% MF B8 (S4). The volatile flavor components were analyzed using headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). And combined with chemometrics, identify the characteristic "stink" substances of stinky mandarin fish. The results showed that a total of 87 volatile compounds were identified by GC-MS, including 22 alcohols, 11 aldehydes, 8 ketones, 9 acids, 8 esters, 23 hydrocarbons, 2 sulfur-containing compounds, 2 nitrogen-containing compounds, and 2 other compounds. Compared with the fresh mandarin fish, the amount of aldehydes and hydrocarbons in fermented samples decreased, while the amount of acids, alcohols, esters, ketones, and nitrogen-containing compounds increased. Through orthogonal partial least squares discriminant analysis (OPLS-DA), variable importance in projection (VIP), and odour activity value (OAV), indicated that indole, trimethylamine, acetic acid and dimethyl disulphide, may be the key characteristic "stink" substances in fermented stinky mandarin fish inoculated by Staphylococcus saprophyticus MF B8. The research results provide a theoretical basis for the formation of volatile flavor compounds in fermented fish products.