Effect of maturity on antioxidant capacity of several tropical fruits.
Wu HisCheng, Ke LihShang
Author Affiliation: Institute of Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung, Taiwan.
Journal of the Agricultural Association of Taiwan 9 : 494-509
Abstract : This study aimed to elucidate the effect of maturity on antioxidant capacity in guava (cv. 'Jen-Ju Bar'), papaya (cv. 'TN 2'), pineapple (cv. 'TN 17'), and mango (cv. 'Irwin'), and a different colour index of banana (cv. 'Formosana') after artificial ripening. Antioxidant capacity was measured in 2 aspects: the concentration of known antioxidants (vitamin C and phenolics), and the ability to scavenge free radicals (ABTS; 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid, and DPPH; 1,1-diphenyl-?-picrylhydrazyl)). Results showed that the total antioxidant capacity increased with the increment of maturity in guava, papaya, pineapple and mango. On the other hand, the total antioxidant capacity in the different ripening colour index of banana showed no significant difference. The antioxidant component of vitamin C content in guava, papaya and mango increased with the increment of maturity, but there was no significant difference between the different maturities of pineapple. The total phenolic content in guava and pineapple increased with maturity, whereas papaya and mango decreased with maturity. The total phenolic content had no significant difference in the different ripening colour index of banana. In these 5 tropical fruits, the mean DPPH radical scavenging ability was highest in guava (94.8%), followed by papaya (68.1%), banana (39.1%), mango (37.9%), and lowest in pineapple (28.5%). As for mean ABTS radical scavenging ability (TEAC, Trolox equivalent antioxidant capacity), guava showed the highest TEAC value (µmole Trolox/g) of 10.07, followed by banana (4.57), papaya (4.34), mango (4.30) and pineapple (2.67). In antioxidant components, guava had the highest vitamin C content (mg/100 g) with 99.72, followed by papaya (74.15), mango (39.84), banana (28.57) and pineapple (20.66). The total phenolic content (mg/100 g) was also highest in guava, followed by pineapple (73.04), banana (58.39), papaya (40.73) and mango (37.14). The relationship between antioxidant components and antioxidant activity are also discussed.