(P06-029-23) Effects of Free Sugars, Organic Acids, and Pectin on the DPPH and ABTS Radical Scavenging Activity in Fruit Juice

Objectives: The antioxidant activity of fruits, such as apples, pears and tangerines, is considered to be an important part of their nutritional properties. However, the effect of free sugar, organic acid, pectin, which are major nutrients of fruits, on the antioxidant activity of fruit has not been accurately reported yet. In this study, we evaluated the effects of free sugars, organic acids, and pectin on the antioxidant activity of apple, pear, and tangerine juices.

Methods: Apple (Malus domestica ‘Borkh’), pear (Pyrus pyrifolia (Burm f.) ‘Nakai’), and tangerine (Citrus unshiu ‘Marcow’) were used as materials of fruit juice. In addition, the effects of antioxidant activities on sucrose, fructose, glucose among free sugars, citric acid, malic acid among organic acids, and pectin in apples, pears, and tangerines were investigated. Antioxidant activity of apple, pear, and tangerine juices was measured by DPPH and ABTS radical scavenging activity.

Results: Free sugar (100 mg/ml, 20 μl), organic acid (100 mg/ml, 20 μl), and pectin solution (5 mg/ml, 20 μl) were added to apple, pear, and tangerine juice (0.5 ml) for spiking. Sucrose, fructose, and glucose had an no effect on the antioxidant activity of fruit juice for DPPH radical scavenging activity. Addition of citric acid and malic acid decreased slightly the DPPH radical scavenging activity in fruit juice, but pectin increased the DPPH radical scavenging activity slightly. Free sugar, organic acid, and pectin had no effect on ABTS radical scavenging activity of fruit juice. Effects of free sugars, organic acids, and pectin on the antioxidant activities were verified using antioxidant standards, trolox. Sucrose, fructose, and glucose was not affected significantly on DPPH and ABTS radical scavenging activity of trolox. Citric acid and pectin showed a tendency to increase the DPPH radical scavenging activity of trolox. Additionally, pectin showed to increase the ABTS radical scavenging activity of trolox significantly.

Conclusions: Free sugars contained in fruits had little effect on the DPPH and ABTS radical scavenging activity of fruit juice. As a result of this study, it is judged that there is no problem with the intake of antioxidant function through the intake of low-sugar fruit juice. In addition, the addition of pectin in fruit- or vegetable-beverages can enhance the antioxidant activity.

Funding Sources: None