Induction of stilbenes in grapes by UV-C: Comparison of different subspecies of Vitis

Bioactive products enriched in stilbenes are considered of potential future interest, and the main sources of stilbenes in human diet are grapes. Postharvest ultraviolet C (UV-C) treatment was used to induce stilbene biosynthesis in grapes of three varieties of Vitis vinifera sylvestris, seven of Vitis vinifera sativa, and two Hybrid Direct Producers (HDPs). Stilbenes have been identified by UPLC-DAD-TQD and quantified by HPLC-DAD, and cluster analyses have been performed to classify subspecies by their stilbene profile. After UV-C treatment, the Syrah variety reached a maximum of 25 mg kg^? 1 f.w. of total stilbenes in the 2008 vintage, and in the statistical analysis, this variety stood out from the other Vitis varieties tested. In 2008, varieties belonging to the sylvestris group and Vitis vinifera sativa Merlot also presented high stilbene production; however, the expected concentration in the HDPs was not obtained.Industrial relevanceIn this study, postharvest UV-C treatment has been applied to obtain stilbene-enriched grapes from several subspecies of Vitis. The most suitable raw material for bioactive stilbene-enriched products, such as nutraceutics and wines, has been established. This is an essential prerequisite to scaling up the process. Such stilbene-enriched products are known to have added-value as a result of the confirmed positive bioactivity of these compounds, and are gaining market acceptance.