Effects of Lacticaseibacillus casei fermentation on the bioactive compounds, volatile and non-volatile compounds, and physiological properties of barley beverage

Barley beverage contains many natural nutrients which is suitable for lactic acid bacteria (LAB) fermentation. The aim of this study was to explore the influences of Lacticaseibacillus casei 17301 fermentation on the bioactive ingredients, volatile and non-volatile compounds, and physiological properties of barley beverages. Our results showed that the total polyphenols and flavonoids in fermented barley beverages remarkably increased compared to those in unfermented barley beverages. A total of 63 volatile compounds in fermented barley beverages at the different fermentation stages were detected using headspace solid-phase micro-extraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), including 17 acids, 16 ketones, 11 aldehydes, and 7 alcohols. Furthermore, untargeted metabolomics analysis-based ultra-performance liquid chromatography quadrupole-time of flight mass spectrometry (UHPLC-QTOF-MS) revealed L. casei 17301 effectively altered the non-volatile compounds, especially indole-3-lactic acid, in barley beverages. Most importantly, the barley beverage fermented with L. casei 17301 had elevated the antioxidant and lipase inhibition activities compared to the unfermented barley beverage. Collectively, L. casei 17301 could ameliorated the functionality and flavor of the barley beverage and the flavor of the product. These results of this study provide a theoretical basis for the development of Lacticaseibacillus-fermented cereal products with beneficial physiological properties.