Impact of maceration duration and microbial consortia on antioxidant capacity and colour characteristics of orange wines

Orange wines, defined as white wines produced with prolonged skin maceration, have recently gained increasing attention due to their distinctive sensory profile and potential functional properties. The maceration process promotes the extraction of phenolic compounds from grape skins, which may influence antioxidant capacity, colour characteristics, and overall oenological features. However, the impact of maceration duration and microbial consortia, including non-Saccharomyces yeasts and lactic acid bacteria (LAB), on these parameters remains insufficiently explored. Therefore, this study aimed to investigate the antioxidant capacity and colour characteristics of white and orange wines produced under different maceration regimes and microbial inoculation strategies. Experimental trials included conventional white wines without maceration and orange wines subjected to short and long maceration periods, with or without sulphite addition. Alcoholic fermentation was conducted using Saccharomyces cerevisiae, alone or in combination with Starmerella lactis-condensi, followed in some trials by malolactic fermentation with Oenococcus oeni or Lactiplantibacillus plantarum. Antioxidant capacity was assessed using a modified DPPH assay and expressed as EC20 values [1], while colour parameters were measured using CIELab coordinates through spectrophotometric analysis. Results demonstrated that orange wines exhibited substantially higher antioxidant capacity compared to white wines, indicating up to 15-folds increase associated with skin maceration. Moreover, wines produced using mixed fermentations with non-Saccharomyces yeasts and LAB generally showed greater antioxidant capacity than those fermented with S. cerevisiae alone, suggesting a positive contribution of microbial diversity to phenolic composition and other antioxidant compounds. Colour analysis revealed significant differences between white and macerated wines, with maceration leading to decreased lightness (L*) and increased redness (a*) and chromaticity (C*), reflecting the enhanced extraction of phenolic compounds. Prolonged maceration further intensified these effects, producing darker and more intensely coloured wines. These results contribute to a better understanding of the biochemical and technological factors underlying the production of orange wines and highlight the importance of microbial selection in optimizing their functional and oenological properties.