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This paper reports the anthocyanin adsorption profiles of the cell walls of different Saccharomyces strains isolated from grapes collected in the Spanish appellation controlée regions of La Rioja, Navarra, and Ribera del Duero. These strains are habitually used in red wine-making. The acyl derivatives of anthocyanins (acetyl and p-coumaryl compounds) were more strongly adsorbed than nonacyl derivatives. Peonidin-3G was also strongly adsorbed, as were its acyl derivatives. The greater presence of acetyl derivatives in the cell wall adsorbate leads to an increase in yellow color and a reduction in blue color with respect to the corresponding wine.

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Torulaspora delbrueckii is a non-Saccharomyces yeast with interesting metabolic and physiological properties of potential use in oenology. This work examines the fermentative behaviour of five strains of T. delbrueckii in sequential fermentations with Saccharomyces cerevisiae, analysing the formation of aromatic compounds, polyalcohols and pigments. The fermentative power of these five strains ranged between 7.6 and 9.0% v/v ethanol; the associated volatile acidity was 0.2-0.7 g/1 acetic acid. The production of glycerol was inferior to that of S. cerevisiae alone. The mean 2,3-butanediol concentration reached in single-culture S. cerevisiae fermentations was 73% higher than in the five sequential T. delbrueckii/S. cerevisiae fermentations. However, these fermentations produced larger quantities of diacetyl, ethyl lactate and 2-phenylethyl acétate than single-culture S. cerevisiae fermentation. 3-ethoxy propanol was produced only in the sequential fermentations. The five sequential fermentations produced smaller quantities of vitisin A and B than single-culture S. cerevisiae fermentation. In tests performed prior to the addition of the S. cerevisiae in the sequential fermentations, none of the T. delbrueckii strains showed any extracellular hydroxycinnamate decarboxylase activity. They therefore produced no vinyl phenolic pyranoanthocyanins.

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Lachancea (kluyveromyces) thermotolerans is a ubiquitous yeast that can be naturally found in grapes but also in other habitats as soil, insects and plants, extensively distributed around the world. In a 3-day culture, it shows spherical to ellipsoidal morphology appearing in single, paired cells or short clusters. It is a teleomorph yeast with 1-4 spherical ascospores and it is characterized by a low production of volatile acidity that helps to control global acetic acid levels in mixed or sequential inoculations with either S. cerevisiae or other non-Saccharomyces species. It has a medium fermentative power, so it must be used in sequential or mixed inoculations with S. cerevisiae to get dry wines. It shows a high production of lactic acid able to affect strongly wine pH, sometimes decreasing wine pH by 0.5 units or more during fermentation. Most of the acidification is produced at the beginning of fermentation facilitating the effect in sequential fermentations because it is more competitive at low alcoholic degree. This application is especially useful in warm areas affected by climatic change. pH reduction is produced in a natural way during fermentation and prevents the addition of tartaric acid, that produces tartrate precipitations, or the use of cation exchangers resins highly efficient reducing pH but with undesirable effects on wine quality. Production of lactic acid is done from sugars thus reducing slightly the alcoholic degree, especially in strains with high production of lactic acid. Also, an improvement in the production of 2-phenylethanol and glycerol has been described.Fermentation 2018, 4, 53 2 of 12 necessary a minimum of 200 mg/L of YAN (yeast assimilable nitrogen) to avoid sluggish or stuck fermentations [7]. Serine as N-source also has shown an improvement in the fermentation performance of LT [8]. Strains of LT can express the following extracellular enzymatic activities with effect in wine aroma or phenol extraction: Esterase, Esterase-Lipase, ß-glucosidase, Pectinase, Cellulase, Xylanase, Glucanase [9].Fermentation 2018, 4, x 2 of 12 LT is able to ferment glucose and sucrose [5] and weakly galactose. It shows variable capacity to ferment maltose, trehalose and raffinose [6]. Nitrogen nutrition is similar to S. cerevisiae being necessary a minimum of 200 mg/L of YAN (yeast assimilable nitrogen) to avoid sluggish or stuck fermentations [7]. Serine as N-source also has shown an improvement in the fermentation performance of LT [8]. Strains of LT can express the following extracellular enzymatic activities with effect in wine aroma or phenol extraction: Esterase, Esterase-Lipase, ß-glucosidase, Pectinase, Cellulase, Xylanase, Glucanase [9].

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