Effect of Anaerobic Pretreatment on Microbial Diversity in Yunnan-Grown Catimor Coffee Cherries and Flavor Components of Coffee Beans

In this study, the microbial community in Catimor coffee cherries produced in Yunan during anaerobic pretreatment was investigated by 16S rDNA and internal transcribed spacer (ITS) amplicon sequencing and the characteristic flavor substances of roasted coffee beans were analyzed by gas chromatography-mass spectrometry (GC-MS). Furthermore, this study examined the correlation between microbial communities and flavor substances. Results revealed that anaerobic pretreatment significantly promoted the proliferation of bacterial genera including Leuconostoc, Pediococcus and Lactobacillus as well as fungal genera such as Wickerhamomyces, Candida, Saccharomyces, Pichia and Aspergillus. The anaerobic pretreatment group exhibited substantial increases in lactic acid, acetic acid, malic acid, and succinic acid contents, with Leuconostoc, Pediococcus, Lactobacillus and Wickerhamomyces identified as possibly key contributors to lactic acid production. Through orthogonal partial least square-discriminant analysis (OPLS-DA), isoamyl acetate, ethyl hexanoate, and acetic acid were identified as characteristic volatile components based on variable importance in projection (VIP > 1) and odor activity value (OAV > 1). Principal component analysis (PCA) further demonstrated that the dominant microbial communities under anaerobic pretreatment played a crucial role in generating key flavor substances such as lactic acid, acetic acid, ethyl hexanoate and isoamyl acetate.