Decreasing the ethanol content in wine is a current challenge, mainly due to the global climate change and to the consumer preference for wines from grapes with increased maturity. In this study, a central composite design (CCD) and response surface methodology (RSM) approach was used to investigate the potential application of Starmerella bacillaris (synonym Candida zemplinina) in combination with Saccharomyces cerevisiae, in mixed (co-inoculated and sequential) cultures, to understand better the mechanism of co-habitation and achieve the objective of reducing the ethanol in wines. Laboratory scale fermentations demonstrated a decrease up to 0.7 % (v/v) of ethanol and an increase of about 4.2 g/L of glycerol when S. cerevisiae was inoculated with a delay of 48 h with respect to the inoculation of S. bacillaris. Pilot-scale fermentations, carried out in winemaking conditions, confirmed the laboratory results. This study demonstrates that the combination of strains and inoculation protocol could help to reduce the ethanol content in wines.

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Background and Aims: The aim of this work was to assess and compare the chemical composition and colour characteristics of Barbera red wines obtained after partial alcohol reduction using three promising methodologies for implementation at the industrial level. Methods and Results: Alcohol reduction was achieved by: (i) pre-fermentation addition of liquid derived from grape must (reverse osmosis by-product); (ii) mixed fermentations with strains of Starmerella bacillaris and Saccharomyces cerevisiae; and (iii) dealcoholisation of wine post-fermentation with a polypropylene membrane. The microbiological approach enabled the production of wines with a slightly lower alcohol concentration (À0.2 to À0.3% v/v), while facilitating the release of anthocyanin and some esters of fatty acids (ethyl hexanoate and ethyl dodecanoate) that could contribute positively to wine aroma with pleasant nuances. The low impact of the partial replacement of grape juice on the chemical composition and chromatic characteristics of Barbera wines makes this technique a good option for reducing the ethanol concentration by up to 1.0-2.0% v/v. In contrast, the use of a polypropylene membrane influenced negatively the composition of red wines by reducing significantly the concentration of esters (À60%) and anthocyanin (À17%), independently of the dealcoholisation level (up to À2% v/v). Conclusions: The alcohol reduction strategies can greatly influence the volatile and phenolic composition of the wine. The choice of either a technological or microbiological approach in the wine industry is dependent on the alcohol reduction required. Significance of the Study: This is the first comparative study of three strategies to reduce the alcohol concentration on the same batch of must/wine.