Effect of different drying methods on color difference, microorganisms and volatile metabolites profiles of Ganpu Tea

In this study, sunlight drying, low temperature drying and hot air drying were used to investigate the effects of different drying methods on color difference, microorganisms and volatile metabolites profiles of Ganpu Tea. The results suggested that the L*, a* and b* values of sunlight drying Ganpu Tea (GPTS) in the traditional drying process were significantly lower than those of low temperature drying Ganpu Tea (GPTL) and hot air drying Ganpu Tea (GPTH). It indicated that sunlight drying could decrease the lightness, redness and yellowness values compared with low temperature drying and hot air drying. 16S rDNA amplicon sequencing analysis showed that GPTS, compared with GPTL and GPTH, significantly increased the abundances of Cyanobacteria while significantly decreasing the abundances of Staphylococcus, Bacillus, Brevibacterium and Brachybacterium. At the genus level, Cyanobacteria was the core functional flora in GPTS, while Brevibacterium and Staphylococcus were the core functional flora in GPTL, and Bacillus was the core functional flora in GPTS. In addition, volatile metabolites profile analysis showed that GPTS significantly increased the volatile metabolites levels of Butanoic acid, 3-hexenyl ester, (E)- and Geranic acid compared with GPTL and GPTH. The research on the effects of different drying methods on the aroma, microorganisms and color of Ganpu tea would provide new strategies for improving the quality and enhancing the aroma of Ganpu Tea.