Effect of the cluster heterogeneity on mechanical properties, chromatic indices and chemical composition of Italia table grapes berries (Vitis vinifera L.) sorted by flotation.

Summary: The impact of cluster heterogeneity on mechanical properties, chromatic indices and chemical composition of Italia table grape berries sorted by flotation was evaluated in this study. The density sorting at commercial harvest permitted to get berries of different ripeness and relatively different quality attributes. Individually, some grape chromatic characteristics, physical characteristics (weight of the whole berry and berry skin), content and composition of reducing sugars, organic acids and phenolic compounds (flavanols of low molecular mass in berry skins) permitted to characterise and to differentiate berries belonging to different density classes. However, the tested mechanical properties were not related to the berry density. When the variables that significantly contributed to the berry differentiation were globally assessed, the chemical parameters related to sugars (142.3-164.4 g kg-1), content of skin oligomeric flavanols [46.3-137 mg (+)-catechin kg-1], berry skin weight (379-607 mg), yellow/blue colour component (26.31-29.96) and chroma (26.40-30.06) were the more representative.