The skin of berries of black, red, grey and pink cultivars of Vitis vinifera L. contain anthocyanins and tanins. High pression liquid chromatographic studies of anthocyanins in normal berries of black cultivars (Cabernet- Sauvignon and Merlot noir) permit to show clearly that the synthesis of these pigments starts early in the skins, about three weeks before veraison. Acylated anthocyanins are also present at this stage and they have a similar evolution than no acylated anthocyanins.
On the contrary, proanthocyanic tanins contents of skins and seeds decrease from the first stage of veraison, initially rapidly then more slowly until the maturity. In grape seeds, the final proanthocyanic tanins content keeps the same whatever the year (DARNÉ, 1991).
In case of «millerandage», some berries have not a regular development and stay very small until the maturity. A lot of these shot grape berries stay green with no viable seeds. Others shot grape berries become pink or red but stay small.
That is why three sorts of shot grape berries of Vitis vinifera are studied : small berries 3 mm in diameter, medium berries from 4 to 6 mm in diameter that stay green until maturity and the medium berries from 4 to 7 mm in diameter which change in color during maturation. Their polyphenolic biochemical evolution was compared with that of normal berries. Polyphenolic metabolism of shot grape berries was not modified, but it was just delayed or blocked. The small berries keep the polyphenolic characteristics of normal berries just after the fruit-setting ; the green medium berries cease evolving approximately one month after the fruit-setting, with maturity, these green medium berries have the characteristic polyphenolic of normal berries in the course of growth (between stages K - L) ; the red medium berries are the only shot grape berries which evolve throughout development of the bunch, but with a delay from approximately 1 month compared to normal berries.
AttachmentsNo supporting information for this article