Authors : Nevzat Artik , Mustafa Karhan and Gonca Aydar
Abstract: Sour cherry juice samples, after being pressed by heating, were divided into two groups as without and with-laccase added with 1000 u.L-1 of laccase at 25 C, 40 C and 50 C during depectinisation. Both groups were oxidized in different durations by airing and then clarified. Samples were filtered through 20 kDa and 100 kDa UF poly sulphone membranes for clarifying. This enabled the determination of the influence of oxidation durations and temperatures on clarity stability together with the activity of added laccase and the natural polyphenoloxidase of sour cherry fruit. The optimal condition to get high clarity was obtained by adding laccase into samples in case of heating to 50 C for 6 hours and filtering through 20 kDa membrane after one hour oxidation. Total phenolic compounds of this sample decreased to 1956 mg.L-1from 2785 mg.L-1 by the application. During the application, changes of NTU value and CPC amount followed an apparent zero-order reaction with activation energies (Ea) of 2.8 and 32.6 kcal.mole-1, respectively. But anthocyanin amount fitted to a first-order reaction with Ea of 27.6x10-6 kcal.mole-1.
Nevzat Artik , Mustafa Karhan and Gonca Aydar , 2004. Effects of Polyphenoloxidase (LACCASE) Application on Clarity Stability of Sour Cherry Juice . Journal of Food Technology, 2: 237-243.