Evaluation of Non-Saccharomyces Yeasts for the Reduction of Alcohol Content in Wine

Abstract

bOver recent decades, the average ethanol concentration of wine has increased, largely due to consumer preference for wine styles associated with increased grape maturity; sugar content increases with grape maturity, and this translates into increased alcohol content in wine. However, high ethanol content impacts wine sensory properties, reducing the perceived complexity of flavors and aromas. In addition, for health and economic reasons, the wine sector is actively seeking technologies to facilitate the production of wines with lower ethanol content. Nonconventional yeast species, in particular, non-Saccharomyces yeasts, have shown potential for producing wines with lower alcohol content. These yeast species, which are largely associated with grapes preharvest, are present in the early stages of fermentation but, in general, are not capable of completing alcoholic fermentation. We have evaluated 50 different non-Saccharomyces isolates belonging to 24 different genera for their capacity to produce wine with a lower ethanol concentration when used in sequential inoculation regimes with a Saccharomyces cerevisiae wine strain. A sequential inoculation of Metschnikowia pulcherrima AWRI1149 followed by an S. cerevisiae wine strain was best able to produce wine with an ethanol concentration lower than that achieved with the single-inoculum, wine yeast control. Sequential fermentations utilizing AWRI1149 produced wines with 0.9% (vol/vol) and 1.6% (vol/vol) (corresponding to 7.1 g/liter and 12.6 g/liter, respectively) lower ethanol concentrations in Chardonnay and Shiraz wines, respectively. In Chardonnay wine, the total concentration of esters and higher alcohols was higher for wines generated from sequential inoculations, whereas the total concentration of volatile acids was significantly lower. In sequentially inoculated Shiraz wines, the total concentration of higher alcohols was higher and the total concentration of volatile acids was reduced compared with those in control S. cerevisiae wines, whereas the total concentrations of esters were not significantly different.

Use of Schizosaccharomyces strains for wine fermentation—Effect on the wine composition and food safety

“…pombe strains was more nearly linear than those of the wild strains and that the wild strains had more similar fermentation kinetics to S. cerevisiae even though they were slightly slower. In each Kutyna et al, 2010;Gobbi et al, 2014;Contreras et al, 2014). Previous studies with S. pombe have showed slight reductions up to 0.5 g/L when compared to the Saccharomyces control (Benito et al, 2013) in some instances.…”

Molecular and Phenotypic Characterization of Metschnikowia pulcherrima Strains from Douro Wine Region

“…This is the first time that this high ethanol tolerance has been reported in M. pulcherrima strains. Indeed, they have been characterized as low ethanol tolerant strains (3-5% v/v) either based on the loss of viability during fermentations with S. cerevisiae and/or by the amount of ethanol produced when in single culture [3,4,[27][28][29]57].…”

Directed metabolomic approaches for the characterization and development of new yeast strains

“…One of the main current focuses of research in M. pulcherrima wine strains is to reduce the alcohol content of wines because of its lower fermentative efficiency and its respiratory metabolism [7,42]. Another point of interest is the production of pulcherrimin pigment that causes certain antimicrobial effect on the other yeast populations, including the spoilage yeast Brettanomyces bruxellensis [39].…”

“…Scientific works about these two species are abundant [7,[39][40][41][42], being the most common non-Saccharomyces species commercially available for wine industry besides Torulaspora delbrueckii strains [10,43,44]. T. delbrueckii showed a low implantation rate in fresh must but, due to its high fermentation power and ethanol tolerance (9-11%), it is one of the non-Saccharomyces yeasts with higher incidence on wine properties and quality.…”

“…Many research groups are currently studying nonSaccharomyces yeasts [3,[6][7][8][9][10] due to their unique physiological properties, which may be useful in innovative winemaking. The presence of non-Saccharomyces wild yeasts in fermentations has been associated, traditionally, with high levels of acetic acid and other off-flavours.…”