Vine Tea Extract Enhanced the Fermentation of Skimmed Milk by Lacticaseibacillus casei

Vine tea extract (VTE), from the traditional Chinese herbal tea, was added to reconstituted skimmed milk; the mixture was fermented with Lacticaseibacillus casei, and fermentation characteristics, flavonoid content, antioxidant capacity (AOC), and viability of L. casei were measured. 2 mg/mL VTE promoted L. casei growth and 8 mg/mL VTE inhibited growth, an effect consistent with observed pH changes. Total flavonoid content and AOC increased with increasing VTE dosage. Dihydromyricetin was partially metabolized during fermentation and accounted for most of the antioxidant function of VTE. 2 mg/mL VTE was optimal for maintenance of probiotic culture and pH stability during cold storage and improved AOC during product shelf life. VTE has the potential to increase the health benefits of probiotic dairy products, and the resulting mixture may be suitable to use as a daily milk-based health drink.