本研究評估17種市售包裝果汁，包含100%純果汁及非100%果汁之主要成份含量與其抗氧化能力。果汁的抗氧化能力則利用捕捉2,2-diphenyl-1-picrylhy- drazyl (DPPH) 與2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)(ABTS) 自由基方法來評估並探討主要成分與抗氧化能力之關係。總酚含量的排序依次為100%葡萄汁＞100%柳橙汁＞非100%果汁。相較於其他果汁，100%柳橙汁則含有高濃度的維生素C。全部果汁樣品之DPPH和ABTS清除能力與總酚含量有較高的相關性 (r > 0.8)。100%柳橙汁中維生素C含量對DPPH和ABTS清除能力則有較高的相關性 (r > 0.95)。在糖類方面，100%柳橙汁以蔗糖含量最高，葡萄糖及果糖含量接近。相反地，100%葡萄汁則以葡萄糖與果糖較高，蔗糖含量較低。此外，在游離胺基酸方面，100%柳橙汁及葡萄汁比非100%果汁有較高之總游離胺基酸含量。本研究結果顯示，100%果汁比非100%果汁有較高的自由基清除率，可能與果汁中含有較高濃度的總酚及維生素C含量有關。

The contents of the major components and antioxidant properties of 17 commercial products of fruit juice including 100% fruit juice and non-100% fruit juice were investigated. Antioxidant activity of the fruit juice was determined by scavenging ability on 1,1-diphenyl-2- picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzthia- zoline-6-sulphonic acid) (ABTS) radicals and their correlations to the total phenolics, ascorbic acid, sugars and free amino acids were also evaluated. The rank order of total phenolics were 100% grape juice > 100% orange juice > non-100% fruits juice. Higher ascorbic acid concentration was found in 100% orange juice. The concentration of total phenolics in all fruit juice significantly (r > 0.8) correlated with scavenging ability on DPPH and ABTS. However, the concentration of ascorbic acid (r > 0.95) in 100% orange juice had higher correlation with the scavenging ability on DPPH and ABTS. Higher sucrose contents but comparable glucose and fructose levels were found in 100% orange juice than those of other fruit juice. In contrast, higher glucose and fructose levels but lower sucrose levels were found in 100% grape fruit juice. In addition, 100% orange and grape juice had higher total free amino acid concentration than non-100% fruit juices. That 100% fruit juice had higher free radical scavenging activity than that of non-100% fruit juice may be related to their high levels of total phenolics and ascorbic acid.