Microbial-associated lipid oxidation drives flavor deterioration of Zanba during storage: Insights from integrated...

This study investigated the mechanisms underlying flavor deterioration in Zanba during storage by integrating microbiome analysis, non-targeted metabolomics, and flavoromics. Microbial succession analysis revealed a transition from raw-material-associated microbiota to lipid oxidation-linked dominant genera, including Pseudomonas, Paenibacillus, Temperatibacter, and Enterococcus. These taxa were strongly associated with lipid degradation and oxidative metabolic activities. Metabolomics profiling identified lipid metabolism-particularly that of linoleic acid and glycerophospholipids-as the most significantly perturbed pathway over storage. Flavoromics further showed a progressive decline in Maillard reaction-derived heterocyclic compounds that contribute to roasted cereal notes, alongside a concurrent accumulation of lipid oxidation-derived aldehydes, alcohols, and ketones. Correlation analyses substantiated that the dominant microbial populations promoted lipid hydrolysis and oxidation, thereby accelerating flavor deterioration. Collectively, these findings indicate that Zanba flavor degradation during storage is primarily driven by microbial-associated lipid oxidation, resulting in a sensory shift from roasted cereal aromas toward rancid off-flavors.