CHANGES IN RESVERATROL CONTENT AND BIOACTIVE PROPERTIES DURING PRODUCTION PROCESS OF RED GRAPE JUICE

In this study, it was aimed to determine the stability and changes of bioactive properties (total phenolic content, antioxidant capacity, and total anthocyanin) and resveratrol contents during the production process of red grape juice. In this context, two red grape varieties (Cabarnet Sauvignon and Papazkarası) were used for grape juice production and juice samples were evaluated from each production step. Resveratrol contents of samples were determined using an HPLC system with C18 reverse phase column and fluorescence detector. Total phenolic content, total anthocyanin, DPPH free radical scavenging and ABTS radical scavenging capacities were determined by spectrophotometric methods. In grape juice production process, bioactive properties decreased particularly in clarification and coarse filtration operations. In the overall process, resveratrol content increased while the total phenolic content and antioxidant activity values remained stable. During processing, the maximum loss, over 50% compared to the initial values, occured in the total anthocyanins.