Enological Repercussions of Non-Saccharomyces Species in Wine Biotechnology

Abstract

The use of non-Saccharomyces yeasts in enology has increased since the beginning of the current century because of the potential improvements they can produce in wine sensory quality. Several review articles have described the potential of some non-Saccharomyces species [1][2][3] and the suitable criteria to select them [4,5] according to the effects of the species on wine color, aroma, body or structure. Most non-Saccharomyces species have low fermentative power, which makes it necessary to use them in sequential fermentations with S. cerevisiae to completely deplete the sugars. Moreover, some of them have slow fermentation kinetics, which is a drawback for a competitive implantation in must containing S. cerevisiae indigenous populations. Emerging technologies to control wild indigenous yeasts can facilitate the development, growth and fermentative activity of the inoculated non-Saccharomyces yeasts and, therefore, the suitable expression of their metabolic properties [6]. This special issue is focused on the description and review of several non-Saccharomyces species with great potential in wine biotechnology, some of which are frequently used at the winery scale, but also produced industrially as dried yeast or liquid inoculant [7].Wine acidity, especially the pH, is a key parameter in wine that controls microbial development and chemical stability. Traditional pH control is driven by acidification processes with tartaric acid or modern ion exchanger techniques, which unfortunately affect sensory quality. The biological modulation of wine acidity can be done efficiently by several non-Saccharomyces species, by the production of lactic acid by Lachancea thermotolerans or succinic acid by Candida stellata, the demalication by Schizosaccharomyces pombe or Pichia kudriavzevii, and the control of volatile acidity in sequential fermentations with Torulaspora delbrueckii or Zygosaccharomyces florentinus highlight the possibilities of non-Saccharomyces in the improvement of wine acidity [8].Biological acidification by L. thermotolerans is a powerful tool to control pH in warm areas [9]. The production of acidity is performed from sugars and the product lactic acid is a stable metabolite during winemaking but also through stabilization and aging. The formation of several metabolites with sensory repercussions has also been described in this species. Acidification by L. thermotolerans is a natural biotechnology that helps to keep lower and more effective levels of molecular and free SO 2 . Currently, in our laboratory we have selected strains of this species able to ferment at more than 12% potential alcohol, which opens the door to single fermentations with single inoculums of L. thermotolerans.Wine deacidification by metabolization of malic acid is an essential step in red winemaking. This acid is unstable during stabilization and aging, and can produce microbial hazes if not eliminated previously. Usually, malic acid is transformed into lactic acid by malolactic fermentation produced by lactic acid bacteria, mainly ...

Non-Saccharomyces in Winemaking: Source of Mannoproteins, Nitrogen, Enzymes, and Antimicrobial Compounds

“…The genus Saccharomyces has been the most industrially used in the production of wine. This aspect has been changing in recent years due to an increased interest in the use of non-Saccharomyces yeasts [1]. The high potential of these yeasts makes them a useful tool for improving oenological parameters such as nutrients content, stability, aromatic profile, or bioactive profile, in spite of their low fermentative power, and, in some cases, their high production of certain metabolites with negative connotations in the wine [2,3].…”

Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2

“…The use of non-Saccharomyces yeasts has the main drawback of being normally little competitive against Saccharomyces, so their successful implantation in the must is not easy and they cannot express their metabolic properties or enzymatic activities. Most non-Saccharomyces usually have lower fermentative power than S. cerevisiae or slower fermentation kinetics (e.g., Sp), which reduces the possibilities of being well implanted [40]. New emerging non-thermal technologies facilitate the use of non-Saccharomyces yeasts by eliminating or strongly reducing wild yeasts from the grapes [2,6,8,14,16,21].…”

Technological Characteristics of Wild Non-Saccharomyces Sourced from Banana Fruit and Honey

“…and harmonization of the microbialtaxonomy employed in food fermentation [8], have led to the adoptionofyeast varieties that aim to satisfy consumer longings for wines with reduced alcohol content [9] and organic acid [10] using commercially tailored wine yeast strains [11] asstandard [12] to identify low alcohol-producing yeast [13][14]. The natural obtainability of yeast strains that possess an ideal blend of oenological properties is decidedly improbable: current interest in non-Saccharomyces yeasts revealed strains possessing interesting oenological properties [4], thusrevealing a new world of improved fermentation of complex and differentiated sensory profiles in wines [15] which have gained importance lately in the biotechnological setting [16].…”