Quantification of stilbenoids in grapevine canes and grape cluster stems with a focus on long-term storage effects on stilbenoid concentration in grapevine canes.

On the one hand there is an enormous amount of underutilized side-streams rich in bioactives during wine-production, while on the other hand there is a growing demand for promising phytochemicals for e.g. dietary and pharmaceutical purposes. In the present study we analyzed the stilbenoid contents of grape canes and grape cluster stems collected in Germany. Likewise we investigated the effect of long-term post-harvest storage on stilbenoid levels in grape canes and also the variability of stilbenoids in grape cluster stems during growth cycle. The predominant stilbenoids in either canes or stems were trans-resveratrol and trans-ε-viniferin. The contents in canes ranged from 441 to 7532 and 1218 to 5341mg/kgDW for trans-resveratrol and trans-ε-viniferin, respectively, depending on variety, vintage and storage time. Within storage of 6 months the content in canes increased by up to a factor of fourteen. Stilbenoid contents in grapevine cluster stems varied from 16 to 289 and 23 to 253mg/kgDW for trans-resveratrol and trans-ε-viniferin, respectively, depending on vintage and wine-growing area.