Changes of anthocyanin and amino acid metabolites in saffron petals (Crocus sativus L.) during fermentation based on untargeted metabolomics

In order to investigate the possibility of fermentation for deep processing of saffron petals, the metabolic profiles of anthocyanins and amino acids in saffron petals were studied by untargeted metabolomics method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS) combined with multivariate statistical analysis. The PCA, OPLS-DA and HCA models were established to analyze the differential metabolites before and after fermentation. Subsequently, the differential metabolites were screened by OPLS-DA with pairwise modeling. The contents of 26 kinds of anthocyanins during fermentation and 23 kinds of anthocyanins after fermentation were significantly different, respectively. After fermentation, the total anthocyanin content increased, and the monomer anthocyanin produced a variety of glucoside anthocyanin. As for amino acid metabolism, there were significant differences in 24 amino acids during fermentation, 27 kinds of amino acids after fermentation, and then the total content of amino acids decreased. In addition, based on the KEEG database, several metabolic pathways during the fermentation process were identified, and the metabolism pathway of anthocyanin is primarily related to anthocyanin biosynthesis, while the metabolic pathway of amino acid is mainly related to metabolic pathways. These findings provide comprehensive insights into the quality improvements of saffron petals wine.