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Purification of polyphenol oxidase and the browning control of litchi fruit by glutathione and citric acid
Author(s) -
Jiang Yueming,
Fu Jiarui,
Zauberman Giora,
Fuchs Yoram
Publication year - 1999
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/(sici)1097-0010(19990515)79:7<950::aid-jsfa289>3.0.co;2-e
Subject(s) - browning , citric acid , polyphenol oxidase , glutathione , ascorbic acid , chemistry , sephadex , biochemistry , cysteine , polyphenol , catechol oxidase , propyl gallate , food science , enzyme , cysteamine , antioxidant , peroxidase
Polyphenol oxidase (PPO, EC 1.10.3.2) was purified to homogeneity from litchi peel yielding a single protein with a molecular weight of about 75.6 kD by Sephadex G‐100 gel filtration, and a 108‐fold purification of PPO achieved. The enzyme was determined to be composed of two similar subunits. Glutathione, L ‐cysteine and citric acid suppressed PPO activity markedly, whereas ascorbic acid and n ‐propyl gallate showed a little inhibition. Moreover, the effect was enhanced by the addition of citric acid. On the basis of the inhibition of PPO activity in vitro , the use of 10 mmol l −1 glutathione and 100 mmol −1 l citric acid was found to give good control of the browning of litchi fruit, and an 80–85% inhibition of PPO activity was observed. It is suggested that application of glutathione in combination with citric acid may slow down the browning of litchi fruit. © 1999 Society of Chemical Industry