Analysis of different fermentation processes of jujube-hawthorn fermented beverage based on untargeted metabolomics and GC-MS.

In this study, we compared two processes: "Lactobacillus single fermentation 36 h→ inactivation→yeast re-fermentation (InLA)" and "Lactobacillus-yeast simultaneous co-fermentation (LSA)," using jujube and hawthorn composite juice as the substrate. We applied non-targeted liquid chromatography tandem mass spectrometry (LC-MS/MS), gas chromatography mass spectrometry (GC-MS), and kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis to evaluate how sterilization affects quality. The results showed that in LSA, the total acid continued to increase, and levels of total phenolics, total flavonoids, SOD activity, and DPPH/ABTS antioxidant capacity were significantly higher than in InLA. The metabolome principal component analysis (PCA) / orthogonal partial least squares-discriminant analysis (OPLS-DA) clearly differentiated the four processes, with the greatest difference observed between LSA and InLA. InLA showed significant decreases in lactic acid, phenolic acid, and functional lipids. LSA enriched pathways such as phenylalanine-phenylpropanoid-pentose phosphate-lipid metabolism and significantly enhanced key floral-fruity aromas, including benzeneacetaldehyde, octanal, 1-octen-3-ol, eugenol, and 2-heptanone (relative aroma activity value, ROAV>1). Conversely, InLA only increased β-damascenone and reduced overall aromatic complexity. Lactobacillus inactivation resulted in the absence of galactose and tyrosine metabolism, with only niacin metabolism being upregulated. Lactobacillus-yeast co-fermentation proved to be synergistic without sterilization, combining high nutritional, functional, and organoleptic qualities. High-temperature inactivation may weaken microbial interactions and is not a preferred strategy. The non-sterilization symbiotic fermentation strategy proposed in this study provides a directly replicable process template for the high-value, industrial production of composite fruit and vegetable juices such as jujube and hawthorn. Combining nutritional, functional, and flavor benefits, it holds promise for advancing traditional fermented beverage production techniques.