Impact of Extended Maceration and Regulated Deficit Irrigation (RDI) in Cabernet Sauvignon Wines: Characterization of Proanthocyanidin Distribution, Anthocyanin Extraction, and Chromatic Properties

The impact of extended maceration (EM) was studied in Cabernet Sauvignon grapes sourced from a vineyard subjected to four regulated deficit irrigation (RDI) treatments: (I) 100% replenishment of crop evapotranspiration (100% ET,), (II) 70% ETc, (III) 25% ETc until veraison, followed by 100% ETc until harvest, and IV) 25% ETc. Each vineyard replicate was made into wine with two replicates designated as controls (10-day skin contact) and two as extended maceration (EM, 30-day skin contact). The mean degree of polymerization (mDP), size distribution, concentration, and composition of wine proanthocyanidins (PM) and monomeric flavan-3-ols of 90 fractions were characterized by preparative and analytical HPLC techniques. The maceration length imparted a larger effect on most chemical parameters. The RDI treatment had no effect on the extraction patterns of anthocyanins, PAs, and/or on the origin of the PM extracted into the wines. Conversely, EM led to anthocyanin losses and increased PA extraction during maceration, with similar to 73% of seed-derived PM. Accordingly, the concentration of monomeric flavan-3-ols, oligomeric (2 <= mDP < 5) and polymeric PM (mDP >= 5) was higher in EM wines. The size distribution of the wines' PM revealed two major peaks as a function of concentration at mDP 2 (22-27% of total PM mass) and at mDP 6-7 (12-17% of total PM mass) and was found to follow a non-normal Rayleigh-type distribution.