Abstract
BACKGROUND/OBJECTIVES: Fermented dairy products typically rely on the starter culture of lactic acid bacteria (LAB), resulting in relatively homogeneous flavor profiles and loss of flavor diversity. METHODS: This study employed flavoromics and untargeted metabolomics to evaluate the flavor modulation effects of rose-aroma producing Kluyveromyces marxianus co-cultured with Lactococcus lactis on the fermented milk. RESULTS: In the co-culture group, K. marxianus (KM) was able to promote the growth of L. lactis (LC). KMLC co-culture exhibited superior sensory evaluation and flavor characteristics and a more pronounced rose aroma compared with the monoculture groups and the commercial fermented milk groups. During the fermentation of the KMLC group, 15 key VOCs were identified through OAV analysis, while 37 key metabolites were identified based on variable importance in projection (VIP) > 1 and probability value (p) < 0.05. Spearman correlation analysis revealed a significant correlation between key metabolites and key VOCs. Furthermore, key metabolites played a crucial role in the formation of floral and fruity flavors by participating in metabolic pathways such as citrate metabolism, nucleotide metabolism, and phosphate metabolism. CONCLUSIONS: This study demonstrated that K. marxianus and L. lactis co-culture could significantly enhance the rose aroma of fermented milk, providing solid evidence for flavor innovation in fermented milk through the application of K. marxianus-composite starter cultures.