Improving the antioxidant activity of yogurt through black and green tea supplementation

This study aimed to improve the bioactive properties of yogurt by adding black and green tea at concentrations of 0.5 and 1% (w/v) (Control (C), B05, B1, G05, and G1). In general, tea addition increased the selected mineral concentrations in yogurt while no change in fat or protein contents was observed. Both black (B05: 148.82; B1: 253.29 lg GAE/g) and green (G05: 630.96 lg; G1: 1264.20 GAE/g) tea have enhanced the total phenolic content (C: 50.79 lg GAE/g) and antioxidant activity of yogurt significantly (P < 0.05), that is 100-times increase in G1 compared to C. Although relatively higher syneresis rates were observed for green tea added yogurt, both teas and their increasing concentrations increased the syneresis. However, higher pH values and generally better textural qualities were observed in green tea-added yogurt samples during storage. Increasing amounts of tea, especially green tea, resulted in a lower overall acceptability of yogurts, the most important reason for which is the decrease in flavour value. This study showed that the bioactive properties of yogurt could be improved through black and green tea additions without harming its microbial (>10(7) cfu/g during storage) and textural qualities and maintaining adequate sensory acceptability.