Microbial dynamics, metabolite and volatile organic compounds profiles of Tianzao (sweet fermented rice) during storage.

Abstract

Tianzao is a traditional fermented food with significant cultural and economic value in China with few studies for the storage cycle. This study explores the microbial community dynamics and metabolites of Tianzao during different storage periods. Tianzao samples stored continuously for months of 3 (T1), 6 (T2), 12 (T3), and 18 (T4) were analyzed mainly through illumina sequencing, GC-IMS (Gas Chromatography-Ion Mobility Spectrometry), and LC-MS (Liquid Chromatography-Mass Spectrometry). The results showed the microbial community structure of Tianzao changed significantly over time. Bacillus had the most abundance among bacterial genus, with the highest percentage in T3. Prevotella was most abundant in T4. Fungal Saccharomycopsis was the most prevalent in T1, T2, and T3. While Aspergillus dominated in T4. For microbial community structure, stochastic processes predominated, with drift being the most significant contributor. Metabolomic analysis showed amino acids were the highest abundance. Temporal analysis revealed significant shifts in metabolic pathways, with distinct metabolite profiles with each stage. GC-IMS highlights the differences in volatile profiles among four stages based on several aspects including fingerprint and PCA (Principal Component Analysis). Correlation analysis demonstrated that microbial community changes were significantly linked to variations in metabolite levels and volatile compounds. The dominant microbial groups, particularly Bacillus and Saccharomycopsis, were closely associated with key flavor compounds. The study shows a integrated overview of the microbial and metabolic dynamics during Tianzao storage, offering insights into improving product quality control.