Alcohol reduction in red wines by technological and microbiological approaches: a comparative study

Abstract

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.

Impact of Must Replacement and Hot Pre-Fermentative Maceration on the Color of Uruguayan Tannat Red Wines

“…These results were expected, because the must replacement of the well-ripened grapes with the must of unripe grapes implicated a decrease in sugar content and pH and an increase of titratable acidity. These data agree with those obtained by Kontoudakis et al [32] and Role et al [33], who proposed a similar but different procedure. Kontoudakis et al [38] proposed the simultaneous reduction of the ethanol content and the pH of the wine by mixing wines, one of them obtained with green grapes and the other with ripe grapes [32].…”

“…Kontoudakis et al [38] proposed the simultaneous reduction of the ethanol content and the pH of the wine by mixing wines, one of them obtained with green grapes and the other with ripe grapes [32]. Moreover, Role et al [33] proposed three alternative procedures to achieve alcohol reduction: (i) pre-fermentation addition of liquid derived from grape must (reverse osmosis byproduct); (ii) mixed fermentations with strains of Starmerella bacillaris and Saccharomyces cerevisiae; and (iii) dealcoholization of wine post-fermentation with a polypropylene membrane. In our research, the partial replacement of grape juice had a low impact on the chemical composition of the wines.…”

“…Most of these techniques have had a substantial impact on the color of red wines [13,31]. More recently, some research groups have evaluated different winemaking techniques to regulate the ethanol content and pH of wines in response to the effect of global warming on the composition of grapes [32][33][34]. The results obtained with the application of these procedures have allowed the reduction of the ethanol content and pH of the wines, but the effects on the sensory characteristics, particularly on the color, have not been conclusive [32,33,35].…”

Reducción del contenido de alcohol y pH de vinos tintos Pinot noir y Tannat empleando uvas con diferentes niveles de maduración

“…Tanto para Pinot noir como Tannat, se observaron valores significativamente mayores de proantocianidinas en los vinos MRA en una vendimia, menores en otra y sin diferencia con los vinos MT en otra. Sin embargo, Rolle et al [20] encontraron que en los vinos en los que se redujo el contenido de alcohol sustituyendo mosto de uva madura por mosto de la misma uva tratado por osmosis inversa, los flavonoles de alto peso molecular disminuyeron. La menor concentración de etanol podría dificultar la extracción de flavonoles polimerizados de las uvas durante la fermentación [33].…”

“…Entre ellas destacan: la cosecha de uvas en una etapa temprana de maduración [11], el agregado de agua yácidos minerales al mosto antes del inicio de la fermentación [12], la introducción de nuevos cultivares y la modificación de las técnicas de manejo del viñedo [13], el uso de glucosa oxidasa (EC 1.1.3.4) [14], el uso de levaduras con un menor rendimiento en producción de etanol [15] y la aplicación de técnicas físicas para reducir parcialmente la concentración de azúcares en el mosto o el alcohol en el vino [16][17][18]. En ese sentido, la sustitución de un parte del mosto de uvas muy maduras por mosto de uvas verdes previamente fermentado [19] o por mosto previamente tratado por osmosis inversa [20] han sido procedimientos propuestos reducir simultáneamente el contenido de etanol y pH de vino.…”