Effect of Lactococcus lactis on Flavor Quality of Fermented Milk Based on Electronic Tongue and Electronic Nose

Objective: The effect of different fermentation characteristics of Lactococcus lactis on the quality of fermented milk was explored. Methods: Fermented milk were made with 191 Lactococcus lactis strains that the flavor and taste of fermented milk were assessed by electronic nose, electronic tongue, and multivariate statistical analysis. Results: Principal component analysis(PCA) showed separation trends in the flavor and taste of the fermented milk samples by the strains that had different acid-producing rates and proteolytic activity. Mann-Whitney test showed that aromatic compounds of the fermented milk made by moderate and fast acid-producing strains more than fermented milk made by slow acid-producing strains, while opposite trends were observed in methane, ethanol and organic sulfur (P<0.01). In terms of taste, there was strong umami of the fermented milk made by slow acid-producing strains and the more sourness of fermented milk made by moderate and fast acid-producing strains(P<0.01). There was a significantly negative correlation between acid-producing capacity and proteolysis level(P<0.01). Conclusion: The fermented milk produced by the fast acid-producing and low proteolysis level Lactococcus lactis had more aromatic compounds, and were sourer, while fermented milk produced by the slow acid-producing and strong proteolysis level strains had more methane, ethanol and organic sulfur, and stronger umami taste. © 2021, Editorial Office of Journal of CIFST. All right reserved.