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The influence of the prefermentative addition of copigments and different winemaking technologies on the polyphenolic composition of Tempranillo red wines after malolactic fermentation, was studied. Six experiments dealing with the prefermentative addition of caffeic acid, rutin, (+) catechin, white grape skin tannin, white grape seed tannin and control wines were realised. Three different winemaking technologies (traditional vinification, prefermentative cold maceration at 6-8 ºC and cold soak at 0-2 ºC with dry ice) were studied. Prefermentative addition of copigments increases anthocyanin copigmentation reactions and produces wines with a greater colour, a higher anthocyanin concentration, a superior contribution of anthocyanins to the colour of the wine, a superior percentage of tannins polymerized with polysaccharides and less astringency.Cold prefermentative maceration increases the extraction of polyphenols, the anthocyanin copigmentation reactions and the polymerization reactions between tannins and polysaccharides.The effectiveness of the combination of copigments and prefermentative maceration treatments was demonstrated by the increase of the concentration of the polyphenolic compounds.

The effect of prefermentative and postfermentative caffeic acid (CFA) addition, prefermentative cold maceration, and a simulation of the micro-oxygenation technique through acetaldehyde addition on the phenolic and color composition of Tempranillo wines was investigated. Cold soaking and dry ice addition were performed as prefermentative techniques. Wines were analyzed after the end of the malolactic fermentation and after 6 and 12 months' storage. The results showed an important effect in wines to which CFA had been added, suggesting intramolecular copigmentation reactions through direct interaction between anthocyanins and free phenolic acids, thereby increasing the acylated anthocyanin fraction with an increase in color stability. The higher concentration of total phenols and lower hue values in CFA-added wines also contributed to the stability of these compounds during storage. Prefermentative cold maceration was shown to be influenced by the vintage. Phenolic acids, the acylated anthocyanin fraction, and total phenolics showed higher values in CFA-added and acetaldehyde-added wines. No differences were found in color density between the control wines and both the prefermentative and postfermentative CFA-added wines. However, a higher anthocyanin polymeric fraction and higher acylated anthocyanins, phenolic acids, and total phenols were observed in the CFA-added wines. The implications of this for the color stability of Tempranillo are also discussed.

Climate change scenarios are predicting an increase in temperature as well as more scarce and torrential rainfall episodes. Due to this, an imbalance between grape technological and phenolic maturity is being observed detrimentally affecting grapes composition. In semi-arid areas, irrigation management is a main field practice to influence grape ripening. The goal of the present study was to investigate in Vitis vinifera L. cv. Bobal grapevine responses to three watering regimes: i) Rainfed, ii) deficit irrigation (DI) replacing only 35% of the estimated crop evapotranspiration (ETc) and ii) full irrigation (FI) replacing 100% ETc. In the mid-summer, rainfed grapevines showed different degrees of water stress determined by midday stem water potentials (Ψstem) ranging from -1.1 to -1.4 MPa depening on the season. Rainfed plants had in all seasons less vigor and production and, at harvest, higher concentrations of total soluble solids (TSS) and grape phenolics compounds, as well as lower pH, with respect to the other water regimes studied. DI grapevines, generally, had intermediate values between Rainfed and FI, which presented extreme values of the studied parameters respect to Rainfed. The effects observed on grape color parameters and phenolic compounds with the Rainfed regime were mainly due to a dehydration of the berry, which lowered the yield and the weight of the berry compared to the irrigated treatments. The lower TSS accumulation in the DI berries with respect to the Rainfed, will favour obtaining wines with lower alcohol content, currently more demanded by the consumers. Besides, despite the differences obtained between water regime treatments in the TSS accumulation, the extractability of the anthocyanins was similar, which is interesting since anthocyanin extraction from grapes is prerequisite to the formation of stable red wine pigments. Although the most convenient irrigation strategy might depend to the wine style to be obtained, DI is a strategy that can help to close the gap in the imbalance between the technological and phenolic maturity, positively affecting vine yield and performance with respect to the rainfed strategy.