Use of image analysis for the study of phenolic compounds of the grape berry skin (Vitis vinifera L., cv Cabernet franc)

The localization and quantitative determination of phenolics in grape berry skins, from the onset of veraison, constitute the first step to understand the évolution of these compounds throughout the maturation process. Histological techniques are appropriate to study the evolution of phenolics but manual countings are long and drudgery and do not allow for reliable quantitative results. The image analysis software "Scion Image" proved to be a good tool to improve the quantitative results. This method permitted also to measure the cells area and the area occupied by phenolic compounds inside the vacuoles. Image analysis could be helpful to the understanding of the évolution of phenolics during maturation and possibly contribute to explain their extraction during macération.