Exploring flavor differences and microbial community characteristics of raw Pu-erh tea from different vintages based...

To better understand how storage time affects raw Pu-erh tea (RAPT) quality. Eight RAPT samples with varying storage durations (2009, 2011, 2013, 2015, 2017, 2021, and 2023) were selected for analysis to evaluate how storage time influences flavor quality and microbial composition, using sensory evaluation, gas chromatography-ion mobility spectrometry(GC-IMS), high-throughput sequencing, and chemometric methods. The results showed that as storage time increased, the color of tea leaves gradually shifted from dark green to brownish yellow, the infusion color transitioned from yellow-green to deep orange-yellow and eventually to brownish red, and the aroma evolved from fresh to aged. In the 10th storage year, the levels of tea polyphenols, flavonoids, and total catechins reached their peak. 3-Methyl Butanal, (E.E)-2.4-heptadienal-D, 1-octen-3-one-M, 3-penten-2-one-M, N-nonanal-M, 6-methyl-5-hepten-2-one, (E.E)-2.4- heptadienal-M, `2-pentyl furan, (Z)-4-heptenal, and nine other characteristic volatiles were key factors influencing aroma transformation. High-throughput sequencing showed that Cyanobacteria, Firmicutes, Acidobacteria, Bacillus, and Clostridium were the dominant bacterial taxa in RAPT storage. Aspergillus, Ascomycota, Basidiomycota, and Cladosporium were the dominant fungal taxa. Cyanobacteria and Firmicutes showed significant positive correlation with 3-methyl butanal, (E.E)-2.4-heptadienal, 3-methyl Butanal, (Z)-4-heptenal, tea polyphenols, free amino acid, and other flavor compounds (P < 0.05). Aspergillus exhibited significant positive correlations with flavone, catechins (+C), epicatechin gallate, and n-nonanal-M (P < 0.05). This study provides insights into flavor quality variation across RAPT storage years and the mechanisms underlying characteristic aroma development.