Development of beverage product from Gynura bicolor and evaluation of its antioxidant activity

Gynura bicolor (Roxb & Willd.) DC. is widely distributed in Asia and is very popular for vegetarian cuisine in Taiwan. This study used G. bicolor as the main ingredient to develop a new vegetable juice. Its chemical composition and antioxidant activity were analyzed, and consumer preferences of G. bicolor vegetable juice (GBVJ) evaluated. The results showed that the major compounds in GBVJ were rutin, β-carotene, anthocyanin, and chlorophyll. The antioxidant activity of GBVJ including 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity, 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and superoxide anion were 85.1%, 95.9%, and 80.1%, respectively. The reducing power was about 60% of that of vitamin C (1 g/L). The consumer preferences for each investigated item were all above 5 points (total score 7 points). These results suggest that GBVJ may have positive effects on the antioxidant activity, and the high consumer acceptance may be used as the preliminary information to support that G. bicolor would be commercially viable in the food industry.