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Bighead carp head soup is a traditional Chinese cuisine with a pleasant aroma, but the effect of fish head phospholipids (FPLs) on the odorants is not fully understood. In this study, nuclear magnetic resonance (NMR), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME–GC–MS) were used to monitor the oxidation products of phospholipids in fish head soup during the cooking process, and the fish head triglycerides (FTGs) were used as controls. In 1H NMR spectra, the signals of unsaturated acyl groups and the oxidation compounds in FPLs were significantly higher than those in FTGs. The results of FTIR showed that the changes of functional group absorptions of the oxidation compounds in FPLs were greater than FTGs. GC–MS demonstrated that FPLs samples produced more lipid-derived volatile compounds than FTGs samples. These results showed that FPLs were more prone to oxidation and could produce more lipid-derived odorants. Therefore, FPLs rather than FTGs, were the main precursor substance of lipid-derived odorants in bighead carp head soup. • NMR, ATR-FTIR and HS-SPME–GC–MS used to monitor phospholipid oxidation in fish head soup. • Unsaturated acyl groups and oxidation compounds in FPLs higher than those in FTGs. • FPLs samples produced more lipid-derived volatile compounds than FTGs samples. • FPLs were the main precursors of lipid-derived odorants in bighead carp head soup. [ABSTRACT FROM AUTHOR]

Vegetables which provide many nutrients are an essential part of human diet. Since raw vegetables usually stay fresh for a short time and rot quickly, microbial fermentation has been used to extend the shelf-life of fresh vegetables, such as pickled cucumbers and beets. In this study, Lactiplantibacillus plantarum DP189 and Leuconostoc mesenterides subsp. mesenteris UA107 were introduced as starter cultures in the fermentation process of Dongbei Suancai, which is a popular traditional fermented vegetables in northeast China. The results showed that the LAB starter inoculation increased the diversity of flora, and Lactiplantibacillus remained the dominant flora in the middle and late fermentation stages. Meanwhile, Dongbei Suancai inoculated with the lactic acid bacteria (LAB) starter produced acid more rapidly, accompanied by better utilization of soluble protein and reducing sugar, increased contents of lactic acid and umami amino acids, and the total amount of volatile flavor substances increased by 12.43 % compared with the control group. Spearman's rank correlation analysis showed that Lactiplantibacillus , Leuconostoc mesenteroides , Acinetobacter , and Pedobacter were closely correlated with physicochemical characteristics and flavor metabolites. In conclusion, inoculating autochthonous LAB starter affected the fermentation through microbial community and metabolic regulation, and improved the quality of Dongbei Suancai. [Display omitted] • The starter improved the physicochemical characteristics and quality of Suancai. • Lactobacillus predominated the later stage of the Suancai fermentation. • 6 organic acids, 17 amino acids and 65 volatile flavours were detected in Suancai. • A correlation among microbiota and metabolites in Suancai was revealed. [ABSTRACT FROM AUTHOR]