Abstract
<title>Abstract</title> <p> The interaction between <italic>Saccharomyces cerevisiae</italic> and co-inoculated lactic acid bacteria (LAB) at defined ratios during simultaneous alcoholic and malolactic fermentation remains largely unexplored, offering a unique perspective that provides new options for winemakers and researchers. This is the first report on the investigation of five LAB inoculation strategies: single <italic>Oenococcus oeni</italic> (OO), single <italic>Lactiplantibacillus plantarum</italic> (LP), and mixed ratios of 1:1 (O1L1), 4:1 (O4L1), and 1:4 (O1L4) co-cultured with yeast. Mixed LAB accelerated fermentation, and <italic>L. plantarum</italic> dominated mixed cultures regardless of initial ratio. A total of 85 volatiles were identified, and each treatment displayed characteristic compounds: OO was distinguished by furfural and 2,3-butanedione; LP by ethyl nonanoate and 4-terpineol; O4L1 by octanoic acid and methyl octanoate; O1L1 by α-terpineol and ethyl butyrate; O1L4 by ethyl lactate and 2-phenylethanol. Sensory evaluation ranked O1L1 highest, with enhanced fruity and floral notes and suppressed green and herbal characters. An OAV-PLS model identified spicy and green as key discriminators. Residual analysis showed O1L1 exhibited the smallest residuals, confirming 1:1 as the optimal ratio for metabolic complementarity and aroma balance. Overall, these findings provide rational design of LAB co-inoculation with yeast for targeted wine aroma. </p>