Effects of the addition of green tea powder on the quality and antioxidant properties of vacuum-puffed and deep-fried Yukwa (rice snacks)

Vacuum-puffing has been found to be a very useful process for production of non-deep-fried Yukwa as it ideally produced highly porous and soft texture. In this study, we compared the effects of different green tea powder (GTP) concentrations of 0, 2, 5 and 10 g/100 g on the qualities of vacuum-puffed Yukwa and deep-fried Yukwa. The fat contents of deep-fried Yukwa were significantly higher than vacuum-puffed Yukwa at the same GTP concentrations. Yukwa bases of 10 g/100 g GTP level contained higher total catechins and caffeine contents for vacuum-puffed Yukwa than deep-fried Yukwa. Vacuum-puffed Yukwa had more total phenolics and flavonoids, and a better scavenging effect on DPPH and reducing power than deep-fried Yukwa at the same green tea concentrations. Vacuum-puffing produced more breakable expanded pellets than deep-frying. The sensory evaluation of Yukwa base showed deep-fried Yukwa added with 2 g/100 g GTP was preferred for all the examined properties.