Changes of phenolic content and activities of phenylalanine ammonia lyase and polyphenol oxidase in relation to discoloration of mango fruit during low temperature storage.
Ketsa S., Chidtragool S.
Author Affiliation: Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand.
: 343-345
Abstract : Mango cultivars Nam Dok Mai and Choke Ann were stored in cardboard boxes at 4°C and later at 25°C. Fruits of Nam Dok Mai showed discolouration of the skin and pulp during storage at 4°C. The discolouration became more severe upon transfer to 25°C. Fruits of Choke Ann did not exhibit discolouration of the skin and pulp during storage at 4°C and only slight discolouration 3 days after storage at 25°C. The total free phenol content in the skin of both cultivars was higher than that of the pulp regardless of storage conditions. The total phenol content in the skin of both cultivars decreased, whereas that of the pulp was stable during storage. Phenylalanine ammonia-lyase activity in the skin of cv. Nam Dok Mai increased more rapidly than in the pulp during storage at 4°C, whereas the activity of the enzyme in both skin and pulp decreased upon transfer to 25°C. Polyphenol oxidase activity in the skin of cv. Nam Dok Mai was higher than that in the pulp, increased to a maximum and decreased thereafter. Polyphenol oxidase activity in the pulp increased more than that in the skin upon transfer to 25°C. Polyphenol oxidase activity in the skin and pulp of cv. Choke Ann showed a similar trend when stored at 4°C. Reduction in the polyphenol oxidase activity in the skin of cv. Choke Ann was higher in the pulp than in the skin.