Simultaneous and sequential inoculation of lactic acid bacteria to engineer the flavor profile of Chinese spicy cabbage: A machine learning and modeling study.

The inoculation timing of starter cultures is a critical factor influencing the quality of fermented foods, yet it remains underexplored. This study evaluated how simultaneous (T1) and sequential (X1) inoculation of Leuconostoc, Levilactobacillus, and Lactiplantibacillus affects inter-species competition and fermentation dynamics in Chinese spicy cabbage (CSC). While the T1 strategy accelerated fermentation kinetics with Leuconostoc acting as the primary fermenter, the inoculation sequence altered the competitive hierarchy of the secondary fermenters: Levilactobacillus dominated in T1, whereas Lactiplantibacillus prevailed in X1. This differential microbial succession resulted in distinct aromatic signatures, with Random Forest modeling identifying methyl allyl disulfide (Day 6) and dimethyl trisulfide (Day 13) as key differential compounds driving these flavor differences. Although the T1 group developed a more intense fermented flavor, sensory analysis indicated that the sequential (X1) strategy achieved higher overall acceptability by yielding a more desirable balance between moderate flavor and preserved texture. These findings demonstrate that adjusting inoculation timing is an effective method to engineer microbial succession and systematically modify the final sensory profile of fermented vegetables.