The combined effect of protein hydrolysis and Lactobacillus plantarum fermentation on antioxidant activity and metabolomic profiles of quinoa beverage.

Lactic acid bacteria fermentation is a commonly applied technique to produce nutritional, functional, and organoleptic enhanced foods. In the present study, protein hydrolysis and Lactobacillus plantarum fermentation were coupled to develop quinoa beverages. Protein hydrolysis effectively promoted the growth and fermentation of L. plantarum. Fermentation alone did not significantly improve antioxidant activity, but the combined use of protein hydrolysis and L. plantarum fermentation significantly improved the antioxidant activity of the quinoa beverage. Nontargeted metabolomics based on UHPLC-Q Exactive HF-X/MS and multivariate statistical analysis were performed to reveal the metabolite profile alterations of the quinoa beverage by different processing methods. A total of 756 metabolites were identified and annotated, which could be categorized into 12 different classes. The significant differentially abundant metabolites were mainly involved in primary metabolite metabolism and secondary metabolite biosynthesis. Many of these metabolites were proven to be vitally important to the function and taste formation of the quinoa beverage. Most importantly, the coupled use of protein hydrolysis and L. plantarum fermentation significantly increased some functional ingredients compared with protein hydrolysis and L. plantarum fermentation alone. The above results indicate that protein hydrolysis coupled with L. plantarum fermentation is an effective strategy to develop functional quinoa beverages.