Fermentation with probiotic Lactobacillae enhances the flavor and bioactive metabolites of a commercial green tea extract

In this study, a reliable and comprehensive in vitro method was established to screen lactic acid bacteria (LAB) with greater potential to enhance the flavor and human health functionalities of green tea extract (GTE). Firstly, 15 LAB strains were selected by accessing the acidity and sensory of fermented green tea extract (FGTE) as well as hemolytic activity and antibiotic sensitivity of LAB. Subsequently, acid and bile salt tolerance, gastrointestinal fluid resistance, antioxidant activity, and adhesion ability were tested for further evaluating the probiotic properties of LAB strains suitable for fermentation of GTE. Principal component analysis (PCA) of these results indicated that Lactiplantibacillus plantarum NCU001692, NCU001698, NCU001679, NCU001685, NCU001683, and NCU001695 could be applied for GTE fermentation. Fermentation with different Lactiplantibacillus plantarum strains has changed the composition of the aroma-active compounds and increased linalool content in GTE detected by HS-SPME-GC-Q-TOF-MS. Meanwhile, GTE fermented by NCU001692 with the most favorable flavor and overall sensory acceptance and improved the antioxidant activity and content of total flavonoids and phenolics. These results indicated that Lactiplantibacillus plantarum NCU001692 has great potential to be used as a probiotic in FGTE products.