DPPH radical scavenging assay measures the hydrogen donating capacity of the antioxidant to the stable free radical DPPH, resulting in the formation of diphenylpicrylhydrazine(Shon et al., 2003). Antioxidant activity may be indicated by the reductive ability of a compound (transformation of ferricyanide complex to ferrocyanide complex) as described by Rama Prabha and Vasantha (2011). In this study, UV-C treated juice samples, except U60 showed significant increase in the percentage of DPPH inhibition when compared to control. The highest percentage inhibition of DPPH was 91.2%(8.99 g AAE/ml) for U30 sample, compared to the control,84.1% (8.29 g AAE/ml). In terms of reducing power, UV-C treated samples (U15 and U30) showed significant increase in comparison with control. The maximum increase in reducing capacity (12%) was from 360.71 g AAE/ml to 405.75 gAAE/ml in control and U30 sample, respectively. As explained previously, stress response induced by UV-C processing may increase extraction of antioxidant compounds and is in agreement with Bhat et al. (2011), where UV-C exposure induces antioxidant capacity of starfruit juice. In addition, enhanced antioxidant capacities may allow additional quenching of active oxygen species, thus being an advantage to health conscious consumers. Nevertheless, Alothman et al. (2009)reported that UV-C treatment can either increase or decreasethe extractability of antioxidants due to some variables includ-ing dose delivered, exposure time, and raw materials used.Thus, UV-C processing variables have to be evaluated appropriately to avoid negative impacts on fruit juice quality. No significant changes were observed in percentage of DPPH inhibition after thermal treatment. Likewise, thermal pasteurized samples showed non-significant decrease in reducing ability (345.10 g AAE/ml) when compared to the control(360.71 g AAE/ml). This is consistent with the study conducted by Goh et al. (2012) on heat treated pineapple juice,where no significant changes in antioxidant activity were observed.