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Characterization of Sultaniye grape ( Vitis vinifera L. cv. Sultana) polyphenol oxidase
Author(s) -
Ümit Ünal Mustafa,
Şener Aysun,
Şen Kemal
Publication year - 2007
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2006.01406.x
Subject(s) - polyphenol oxidase , chemistry , ascorbic acid , catechol , vitis vinifera , catechol oxidase , polyphenol , sodium metabisulfite , activation energy , substrate (aquarium) , enzyme , nuclear chemistry , horticulture , food science , biochemistry , peroxidase , biology , antioxidant , organic chemistry , ecology
Summary Polyphenol oxidase (PPO) was extracted from Sultaniye grapes grown in Turkey, and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. Optimum pH and temperature for grape PPO were found to be 3.4 and 30 °C, using catechol as substrate. K m and V max values were found to be 44.5 ± 5.47 m m and 0.695 ± 0.0353 OD 410 min −1 , respectively. Four inhibitors were tested in this study and the most potent inhibitor was sodium metabisulphite, followed by ascorbic acid. From the thermal inactivation studies in the range of 65–80 °C, the half‐life values of the enzyme ranged between 2.6 and 49.5 min. Activation energy ( E a ) and Z values were calculated to be 208.5 kJ mol −1 ( r 2 = 0.9544) and 10.95 °C ( r 2 = 0.9517), respectively.