Intense UV irradiation totally transforms resveratrol into a compound (F-1) highly #uorescent
in the UV range. A similar compound (F-2) is present in red wines. Irradiation of wine leads to
the complete disappearance of both cis and trans isomers of piceid with the formation of F-2, and
to a large decrease in resveratrol isomers content, associated with the formation of F-1. Another
#uorescent compound (F-3) also appeared, but its origin is unknown