Flavonoids in Gran Negro berries collected from shoulders and tips within the cluster, and comparison with Brancellao and Mouratón varieties

► Great increase of anthocyanins in shoulders between 2nd and 3rd sampling. ► Total flavonols reached maximum values from the first sampling. ► Malvidin derivatives were the main responsibles for the trend of anthocyanins. ► Flavonols were minor compounds with respect to anthocyanins. ► Glucosides group > coumaroyl glucosides > acetyl glucosides > caffeoyl glucosides.