Abstract:

Polyphenolic extracts from Herba Gei and Herba Lysimachiae were blended and added to kiwifruit juice in order to explore the effects of their presence on the peroxide value of kiwifruit juice exposed to ultraviolet light, temperature or hydrogen peroxide using BHT as control. In addition, the effect of volume ratio between the two polyphenolic extracts on the peroxide value of kiwifruit juice was also investigated, and the abilities of their blends at different ratios to scavenge hydroxyl free radicals were assessed. After thermal treatment at 90 ℃for 6 h, the peroxide value of kiwifruit juice added with a blend of polyphenolic extracts from the two species of plants at 1:1 was 8.55% and 24.57% lower than those of blank kiwifruit juice and kiwifruit juice added with BHT. When thermal treatment at 90℃ for 6 h was replaced by 0.5% hydrogen peroxide oxidation and ultraviolet light illumination for the same period of time, 9.08% and 1.83% decreases in the peroxide value of kiwifruit juice were achieved by replacing BHT with a blend of polyphenolic extracts from the two species of plants at 1:1 and the peroxide values of kiwifruit juice added with the blend were 17.55% and 3.57% when compared with blank kiwifruit juice. The blend of polyphenolic extracts from Herba Gei and Herba Lysimachiae at a volume ratio of 3:1 presented the highest antioxidant effect and its hydroxyl free radical scavenging ratio was 1.37 times higher than that of BHT. The presence of the blend with the highest antioxidant effect resulted in 56.27% decreases in the peroxide value of kiwifruit juice when compared with the presence of blank, respectively.

Key words: polyphenolic extract blend, kiwifruit juice, antioxidation, peroxide value