Cell wall polysaccharides, phenolic extractability and mechanical properties of Aleatico winegrapes dehydrated under sun or in controlled conditions

Aleatico is an Italian red winegrape variety traditionally used partially dehydrated to produce Passito wines. The aim of this research is to assess the effect of two different off-vine withering techniques (natural sun-exposed: SUN, and controlled temperature and humidity conditions: CTR) on grapes physicochemical modifications, focusing on mechanical properties, phenolic profile, and cell-wall polysaccharide structures. The composition and extractability of polyphenols were studied before and after the two withering processes, differentiating the tissues (skin, pulp, seeds). A stronger effect on cell-wall polysaccharides composition pectin was highlighted by chemical and immunochemical approaches in SUN skins at the level of pectin chains and de-esterification, affecting grapes mechanical properties, especially for skin rigidity (