Resveratrol and piceid isomers concentrations in grapevine shoots, leaves, and tendrils

The objective of this study was to evaluate the levels of cis- and trans-isomers of resveratrol and piceid contained in the shoots, leaves and tendrils of six grapevine varieties and three locations processed under two different drying conditions. The highest trans-resveratrol content was found in the shoots; trans-piceid was contained in lesser amounts (7%) and cis-forms only in very small amounts (similar to 1%). In leaves, both forms of piceid were dominant, while in tendrils trans- and cis-forms of piceid were dominant in samples dried in the laboratory oven at 40 degrees C. Pinot Noir differed from other varieties with a high trans-resveratrol amount. Growing location affected trans-resveratrol levels. Our results suggest that the trimmed clippings might be used as a valuable and inexpensive source of stilbenes. Clippings preserved by drying might be further processed to nutraceuticals or as an additive to the feed.