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INVOLVEMENT OF PEROXIDASE AND POLYPHENOL OXIDASE IN MANGO SAP‐INJURY
Author(s) -
JOHN K. SABY,
BHAT S.G.,
RAO U.J.S. PRASADA
Publication year - 2002
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.2002.tb00762.x
Subject(s) - polyphenol oxidase , peroxidase , polyphenol , browning , chemistry , food science , catechol oxidase , terpenoid , botany , horticulture , biochemistry , enzyme , antioxidant , biology
Sap (latex) that oozes out from mango during harvest, upon contact with the fruit, causes dark spots (sap‐injury) on the peel and reduces consumer acceptance and shelf‐life of fruit. In this investigation different components responsible for sap‐injury were identified. Mango saps from four Indian varieties were collected and separated into aqueous and nonaqueous phases. Whole sap, aqueous phase and nonaqueous phase were tested for their ability to cause sap‐injury (browning) on mangoes. The nonaqueous phase caused maximum injury and the extent of injury caused by nonaqueous phases from different varieties was varied. Limonene, ocimene and β‐myrcene, the major terpenoids identified in saps of Indian varieties, caused injury. Similar type of injury on mangoes was also caused by organic solvents. Damage on Totapuri mango fruit was significantly lower compared to other varieties, whereas Totapuri nonaqueous phase caused injury on all other varieties. The peel of Totapuri variety had very low level of polyphenol oxidase, peroxidase and polyphenols compared to other varieties. Thus, a clear relation was found between the peel polyphenol oxidase, peroxidase activities, the polyphenol content in the peel and the extent of injury. Further, nonaqueous phase applied on peels previously heat‐treated at 95C for 5 min, neither caused injury nor showed any enzyme activity. Thus, the results indicated that the terpenoid components of sap and polyphenol oxidase, peroxidase, polyphenols of peel are involved in sap‐injury .