Green tea powder supplementation enhances fermentation and antioxidant activity of set-type yogurt.

Yogurt is a fermented dairy food produced by growth of lactic acid bacteria (LAB). Green tea is associated with beneficial health effects. Thus, the aim of this study was to evaluate the effects of green tea powder (GTP) on the fermentation and bioactive properties of yogurt. Yogurt was supplemented with 0-3% GTP (w/v), and effects on fermentation were determined. In addition, antioxidant and anti-inflammatory effects of GTP supplemented yogurts were determined in HT-29 colon cells. GTP (1-3%) supplementation significantly increased the acidification rate and growth of LAB during yogurt fermentation. Removal of free radicals and cellular H2O2, and an increase of antioxidant Nrf2 and HO-1 proteins were observed in the 1-3% GTP groups. Yogurt extracts with 0-3% GTP showed decreased expression of TNF-α and IL-1β in cells. In summary, addition of GTP can enhance the beneficial health effects of yogurt by increasing its antioxidant activity, LAB growth and anti-inflammatory effects.