A Comparative Study on the Modification of Polyphenolic, Volatile, and Sensory Profiles of Merlot Wine by Indigenous Lactiplantibacillus plantarum and Oenococcus oeni

Background and Aims. The variation of malolactic fermentation (MLF) behavior between Oenococcus oeni and Lactiplantibacillus plantarum is crucial for wine quality. This work aimed to evaluate the fermentation kinetics of preacclimatized indigenous O. oeni (strains of SD-2a and 144-46) and Lp. plantarum (strains of XJ25 and XJA2), and their effect on color, polyphenols, volatile components, and sensory characteristics of wine. Methods and Results. The changes of polyphenols, color, volatile components, and sensory properties of a low-pH Merlot wine (pH < 3.3) after MLF with indigenous O. oeni and Lp. plantarum strains were investigated and compared. O. oeni gave wine more floral and balsamic aromas and increased the proportion of co-pigmented anthocyanins. Only strain 144-46 of O. oeni could complete fermentation during 6-day MLF (final concentration of L-malic acid <0.1 g/L). However, both Lp. plantarum strains effectively and thoroughly metabolized L-malic acid within 3 days for XJA2 and 5 days for XJ25 while maintaining a substantial population of viable cells. Lp. plantarum significantly enhanced the proportion of polymerized anthocyanins and the fruity, caramel, fatty, roasted, and herbaceous notes in wine through the modification of volatile profiles. Conclusions. Lp. plantarum after preacclimation shows more robust MLF performance compared to O. oeni. O. oeni prefers to give wine more floral and balsamic aromas, and a high proportion of co-pigmented anthocyanins. Lp. plantarum prefers to give wine more herbal and chemical aromas and a high proportion of polymerized anthocyanins. Significance of the Study. Lp. plantarum after preacclimation exhibits more favorable effects on wine compared to O. oeni., suggesting its potential for industrial application.