Effect of pasteurization and sugar on phenolic content, ascorbic acid and antioxidant activity of Ya-Nang (Tiliacora triandra Diels) juice

Abstract

Ya-Nang is a local plant that has many nutritional values such as protein, dietary fiber, vitamins, and minerals. Presently, Ya-Nang leaves are processed into healthy or functional drinks. Therefore, this research aimed to study the effect of sugar added and pasteurization on bioactive compounds and antioxidant activities by comparing with fresh Ya-Nang leaf juice. The experiments were divided into 4 experimental samples (treatments) which were Ya-Nang juice without sugar added and no pasteurized (YC), Ya-Nang juice with sugar added and no pasteurized (YS), Ya-Nang juice without sugar added and pasteurized (YP), and
Ya-Nang juice with sugar added and pasteurized (YSP). The result revealed thatpasteurization affects the chemical and physical changes of the Ya-Nang juice. Pasteurized Ya-Nang juice decreased in lightness value (L*) and pH. When considering bioactive compounds (total phenolics and ascorbic acid) in both unpasteurized of Ya-Nang juice without and with sugar (YC and YS) had similar initial content (p>0.05). After pasteurization of Ya-Nang juice, the content of phenolics and ascorbic acid was reduced. In addition, the pasteurized Ya-Nang juice, both without and with sugar reduced antioxidant capacity, by the values decreased from 0.47% (YC) and 0.79% (YS) to 0.33% (YP) and 0.67% (YSP), respectively. From the results of this research, it was concluded that the sugar added or pasteurization, and sugar added combined with pasteurization affects the content of bioactive compounds and antioxidant activity of Ya-Nang juice.