|
To examine enzymatic browning of apple wine, changes of alive bands of polyphenol oxidase (EC 1.10.3.1) as well as polyphenol substances related to browning of apple wine were investigated during wine brewing. The decrease of total phenol was remarkably inhibited by the addition of sodium metabisulfite. In the meantime, autoroxidation of catechol in a model system increased proportionally as the reaction pH and temperature increased. Catechol oxidation, however, was not detected at 4 below pH 5.0. Polyacrylamidegel electrophoretic patterns showed that the apple (Jonathan) indicated 4 bands with polyphenol oxidase activity, designated a, b, c and d whose Rm were 0.21, 0.30, 0.41 and 0.51, respectively. Among these, 2 bands, a and c remained until 5th day fermentation and only c band after 6th day fermentation. After pasteurization of apple wine at 60℃ for 30min, c band also remained.
|