บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Antioxidative ability of cell wall components in fruit against ascorbic acid oxidation

Y. Motomura and Y. Yoshida

Fac Agric. Life Sci., Hirosaki Univ., Bunkyo-cho 3, Hirosaki, Japan , Hirosaki, Aomori, Japan, 136-8561

2002

บทคัดย่อ

Antioxidative Ability of Cell Wall Components in Fruit Against Ascorbic Acid Oxidation

Ascorbic acid (AsA) oxidizes rapidly in an aqueous solution and/or in the presence of copper ions. UV absorbance of an aqueous solution of AsA decreased remarkably with time and had nearly disappeared after 12 hrs. When the fractionextracted with water from alcohol-insoluble rsidue of fruit flesh was added to an AsA solution, the decrease in UV absorption slowed in comparison to the control. Among 18 varieties of fruit, the fraction from the flesh of melon , loquat and strawberry demonstrated remarkable effect in amintaining UV absorbance (higher antioxidant activity), while that of grape, mango and kiwifruit showed lower activity. Among the fractions extracted with water, hot water, HCI and KOH successively, water and hot water soluble fractions showed activity, while no activigy was found in the HCI and KOH soluble fractions. In apple and pear fruit, the activity varied with cultivar,and increased with maturity, and by storage in apple. Using fractionation by gel permeation chromatography, water and hot water soluble fractons from apple flesh were separated into four subfractions, and antioxidant activity of each subfraction was evaluated. The highest activity was found in the subfraction which included lower molecular-weight substances. In an AsA solution with added CuSO4, UV absorbance decreased quickly and had hearly disappeared within 15 min. In a mixture of hot water fraction, CuSO4 and AsA, UV absorbance decreased slightly at a slower rate than in comparison to the solution without the hot water fraction. In an AsA solution with pectin from apples and lemons, the decrease in UV absobance was noticably inhibited. Pectins with a low rate of esterification displayed a relatively higher level of activity that those with a high rate of displayed a relatively higher level of activity than those with a high rate of esterification. These results suggest that pectic compounds can include antioxidantive components.