Co-fermentation of Pichia kudriavzevii and Millerozyma farinosa modulates fungal community and enhances flavor in Yangjiang douchi

), were isolated and identified from Yangjiang fermented douchi. The optimal fermentation conditions-9% salt content, 34 °C, 4% inoculum size, and a 1:2 inoculum ratio-were determined based on amino acid nitrogen and total acidity. Using a Co-fermentation strategy combined with MiSeq sequencing and gas chromatography-mass spectrometry (GC-MS), we investigated the influence of microbial communities and flavor compounds during douchi post-fermentation. Results revealed 156 volatile compounds identified by GC-MS, with their content increasing approximately 6.7-fold during ZF fermentation. Specifically, the ester content in Z10 was 1.38 times higher than that in Y30, and the phenethyl alcohol content in Z10 was 2.4 times higher than that in Y20. This study provides a theoretical and technical basis for regulating the microbial community in fermented black bean production and for optimizing industrial manufacturing processes.