Optimisation of an oak chips-grape mix maceration process. Influence of chip dose and maceration time

• The addition of oak chips during red-wine fermentation has been evaluated.
• That wood-grape mix maceration process increased the content in co-pigments.
• Pigment content and colour effects depend on the maceration time and chip dose.
• More stable colour in wines fermented with oak chips and shorter maceration time.
• Long maceration with oak chips could favour lighter colour by pigment adsorption.

Oak chips-related phenolics are able to modify the composition of red wine and modulate the colour stability. In this study, the effect of two maceration techniques, traditional and oak chips-grape mix process, on the phenolic composition and colour of Syrah red wines from warm climate was studied. Two doses of oak chips (3 and 6 g/L) at two maceration times (5 and 10 days) during fermentation was considered. Changes on phenolic composition (HPLC–DAD–MS), copigmentation/polymerisation (spectrophotometry), and colour (Tristimulus and Differential Colorimetry) were assessed by multivariate statistical techniques. The addition of oak chips at shorter maceration times enhanced phenolic extraction, colour and its stabilisation in comparison to the traditional maceration. On contrast, increasing chip dose in extended maceration time resulted in wines with lighter and less stable colour. Results open the possibility of optimise alternative technological applications to traditional grape maceration for avoiding the common loss of colour of wines from warm climate.