Sensorial, biochemical and molecular changes on Raboso Piave grape berries harvested by applying double reasoned maturation and late harvest techniques

At ripening Raboso Piave grapes are characterized by peculiar organoleptic traits, such as high acidity and astringency. Because of these characteristics, the consumption of the wine obtained from this cultivar is not widely diffused. To overcome this limitation, researches have been carried out for altering the polyphenols profile by mainly applying different harvest techniques. Aim of this work was to investigate sensorial, biochemical, and molecular changes occurred in Raboso Piave grape berries subjected to Late Harvest (LH) and Double Reasoned Maturation (DRM) techniques. Particular attention was paid to changes on the biosynthetic pathways of polyphenols, considering their influence on wine organoleptic and quality traits. As highlighted by the sensory analysis results, significant changes on polyphenols profile occurred in grape berries harvested by applying these techniques, but particularly when DRM was applied. In fact in DRM-grape berries, the flavonols and cathechin accumulation were induced and depressed, respectively. In parallel with these changes, the transcription of the Flavonol synthase and the accumulation of Leucoanthocyanidin-reductase mRNAs were induced and depressed, respectively. These modifications allow to maintain a brighter color as well as to reduce the level of astringency in the wine.