| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 97 === ''Jenju Bar'' guava (Psidium guajava cv.'' Jenju Bar '') and'' Tainong No. 2'' papaya (Carica papaya cv.'' Tainong No.2 '') are common tropical fruits in Taiwan with high antioxidant activity. In this study, I investigated the antioxidant activity of these two fruit species in different maturity by ferric reducing antioxidant activity (FRAP) assay, I also measured the antioxidant content such as vitamin C and total phenolic compound (TPC).
By investigating different diameter of guava fruits, the antioxidant activity of guava fruit generally decreased with the enlargement of fruit. In ‘Jenju Bar’ guava, summer crops took 113 days from bloom to maturity and winter crop needed 140 days, but the changes of antioxidant activity and antioxidant content are similar. The antioxidant activity and phenolic compound decreased with fruit development, but the content of vitamin C increased at mature stage. Mature summer crops had higher total phenolic compound, but mature winter crops had higher vitamin C content. Although the concentration of antioxidant content diluted during fruit expansion, the total antioxidant activity and antioxidant content of single fruit accumulated continuously.
‘Tainong No. 2’ papaya fruit showed a different trend from ‘Jenju Bar’ guava fruit, the antioxidant activity, vitamin C and phenolic compound rose during 56 days after bloom (DAB) to 196 DAB. The increasing trend is more obvious in the ripening stage.
I also modified the data of whole tree fruits as ten sections to investigate the antioxidant activity of papaya fruit during development. When the fruits became mature with the increasing section, the antioxidant activity and antioxidants showed a downward first and then upward trend. The antioxidant activity and antioxidants content of fruits in early stage are higher than that of middle stage and similar to that of mature stage.
The ripening treatment raised the antioxidant activity and antioxidants of papaya fruits. Papaya treated with calcium carbide for 2 days and then stored in 25 ℃ for 3 days to achieve full ripening, the antioxidant activity, vitamin C and phenolic compound of fruit pulp are 24%, 54% and 26% higher than those before ripening.
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