Untargeted metabolomics revealed the product formation rules of two fermented walnut milk

Abstract

ABSTRACT This study employed untargeted metabolomics to reveal the changes in the metabolic profile of walnut milk under two different processing methods. The walnut milk of the control group was not treated, which was fermented through L. plantarum in F group, while the walnut milk after proteolysis was fermented in EF group. The results showed that fermentation gradually reduced the pH of walnut milk to 4.70 and 3.61 in F and EF group respectively, for viable count which are 2.9 × 109 CFU/mL and 9.3 × 109 CFU/mL. The antioxidant activity of EF group is significantly higher than Con group (p < 0.05). Through UHPLC-Q-TOF MS and multivariate statistical analysis, the identified metabolites were mainly lipids and lipid-like molecules, as well as organic acids and derivatives. Compared with fermented walnut milk, fermentation after proteolysis significantly increased the functional metabolites contained in walnut milk which are included in antibacterial, antioxidant, anti-inflammatory.