Correlation between browning degree and composition of importantTurkish white wine grape varieties

This study was undertaken to investigate the correlation between browning degree and composition of important Turkish white wine grape varieties during the 2006 and 2007 seasons. Large seasonal and cultivar variations were found in all measured variables. The highest browning degree was found in the Narince cultivar in both years, followed by Emir and Sultaniye, with Narince being the most susceptible to browning and Sultaniye being the least. No correlation (P < 0.05) was found between browning degrees and cysteine, glutathione, polyphenol oxidase activity, or total phenolic contents. Effects of harvest year and variety on all measured parameters, except total phenolics, were statistically significant (P < 0.01).