Carlos Escott

Formation of polymeric pigments in red wines through sequential fermentation of flavanol-enriched musts with non-Saccharomyces yeasts

Non-Saccharomyces yeasts may contribute to enrich wine aroma while promoting the formation of stable pigments. Yeast metabolites such as acetaldehyde and pyruvate participate in the formation of stable pigments during fermentation and wine aging. This work evaluated the formation of polymeric pigments in red musts added with (+)-Catechin, ProcyanidinB2 and ProcyanidinC1. The non-Saccharomyces yeasts used were Lachancea thermotolerans, Metschnikowia pulcherrima and Torulaspora delbrueckii in sequential fermentation with Saccharomyces cerevisiae and Schizosaccharomyces pombe. Use of Lachancea thermotolerans led to larger amounts of polymeric pigments in sequential fermentation. (+)-Catechin is the flavanol prone to forming such pigments. The species Metschnikowia pulcherrima produced higher concentration of esters and total volatile compounds. The sensory analysis pointed out differences in fruitiness and aroma quality. The results obtained strengthen the fact that metabolites from non-Saccharomyces yeasts may contribute to form stable polymeric pigments while also influencing wine complexity.

Use of non-Saccharomyces yeasts and oenological tannin in red winemaking: Influence on colour, aroma and sensorial properties of young wines

Today, many non-Saccharomyces strains have been verified can be positive for the development of wine anthocyanin and aroma in different fermentation scenarios. Moreover, oenological tannins are widely used in wine industry to improve the colour profile and aroma complexity. The aim of this work is to analyze the fermentation characters of non-Saccharomyces strains and investigate the effects of pre-fermentative addition of oenological tannins on the wine components as well as sensory properties. For this purpose, five selected non-Saccharomyces strains and grape seed tannin were used to carry out the different fermentation trials. As a result, the grape seed tannin were less likely to influence growth kinetics of non-Saccharomyces strains. Schizosaccharomyces pombe has been proved can be effective to reduce the malic acid content while increase the level of vinylphenolic pyranoanthocyanin, which is positive for wine colour stability. Pre-fermentative use of oenological tannin was verified could be beneficial for the wines fermented with non-Saccharomyces regarding the improvement of wine colour, anthocyanin composition and the complexity of volatile compounds. Nevertheless, sensory analysis showed that oenological tannin could be less effective to modify the aroma impression of non-Saccharomyces wines.

The Effects of Pre-Fermentative Addition of Oenological Tannins on Wine Components and Sensorial Qualities of Red Wine

Today in the wine industry, oenological tannins are widely used to improve wine quality and prevent oxidation in wine aging. With the development of tannin products, new oenological tannins are developed with many specific functions, such as modifying antioxidant effect, colour stabilization and aroma modifications. The aim of this work is to investigate effects of pre-fermentative addition of oenological tannins on wine colour, anthocyanins, volatile compounds and sensorial properties. In this case, Syrah juice was extracted with classic flash thermovinification from fresh must in order to release more colour and tannins. Three types of oenological tannins, which are, respectively, derived from grape skin, seed (Vitis vinifera) and French oak (Quercus robur and Querrus petraea), were selected to carry out the experiments with seven treatments. Results indicated that tannin treatments significantly improved wine aroma complexity and sensorial properties. However, the concentration of some stable pigments such as Vitisin A, Vitisin A-Ac and Vitisin B was negatively affected by tannin additions. Nevertheless, by means of cluster analysis and principal component analysis, it was observed that higher alcohols were significantly promoted by grape seed tannin while most anthocyanins can be improved by addition of grape tannins. In conclusion, low amount of oenological tannin derived from grape seed is a promising method to be applied especially for young red wine making.

Use of non-Saccharomyces in single-culture, mixed and sequential fermentation to improve red wine quality

The use of non-Saccharomyces yeasts can provide advantages in winemaking such as: a reduction of ethanol content, the synthesis of certain metabolites that are important for color stability or a good yield in the production of certain volatile compounds (ethyl lactate, 2,3-butanediol, 2-phenylethyl acetate). The main objective was general evaluation of wines made by non-Saccharomyces yeast under different fermentation trials compared to wines made by Saccharomyces cerevisiae. Single pure fermentations were performed by two strains of S. cerevisiae (used as controls) and two strains of Schizosaccharomyces pombe. The yeasts Lachancea thermotolerans and Torulaspora delbrueckii were tested in sequential fermentations with S. cerevisiae strains. The effect on acidity due to the interaction between L. thermotolerans and S. pombe in a mixed fermentation was studied. Sequential fermentations with L. thermotolerans and S. cerevisiae can reduce the ethanol content and increase the content of glycerol and pyruvic acid; in addition, the use of L. thermotolerans can increase the lactic acid content, while the mixed fermentations of S. pombe and L. thermotolerans may increase the acetaldehyde content and may also reduce the ethanol content. However, these samples require more time to complete the fermentation. Single pure fermentations by S. pombe can increase the amounts of vitisins, acetaldehyde and glycerol and the amounts of acetic acid. The use of L. thermotolerans in a sequential fermentation allowed an increase in fruitiness and body character of red wine.

Characterization of polymeric pigments and pyranoanthocyanins formed in microfermentations of non-Saccharomyces yeasts.

To assess the influence of non‐Saccharomyces yeasts on the pyranoanthocyanins and polymeric pigments formation after the addition of (+)‐catechin and procyanidin B2 to fresh red grape must.

Effect of Lachancea thermotolerans on the Formation of Polymeric Pigments during Sequential Fermentation with Schizosaccharosmyces pombe and Saccharomyces cerevisiae

Anthocyanins in red grape musts may evolve during the winemaking process and wine aging for several different reasons; colour stability and evolution is a complex process that may depend on grape variety, winemaking technology, fermentative yeast selection, co-pigmentation phenomena and polymerization. The condensation of flavanols with anthocyanins may occur either with the flavylium ion or with the hemiacetal formation in order to produce oligomers and polymers. The kinetics of the reaction are enhanced by the presence of metabolic acetaldehyde, promoting the formation of pyranoanthocyanin-type dimers or flavanol-ethyl-anthocyanin structures. The experimental design carried out using white must corrected with the addition of malvidin-3-O-glucoside and flavanols, suggests that non-Saccharomyces yeasts are able to provide increased levels of colour intensity and larger polymeric pigment ratios and polymerization indexes. The selection of non-Saccharomyces genera, in particular Lachancea thermotolerans and Schizosaccharomyces pombe in sequential fermentation, have provided experimental wines with increased fruity esters, as well as producing wines with potential pigment compositions, even though there is an important reduction of total anthocyanins.

Effects of ultrasound treatment on the phenolic fraction of a red wine aged on lees

Sonication is an emerging non-thermal technology useful to disrupt cell wall and increase polysaccharides release when applied to red wines aged on lees. At the same time, ultrasound treatment may cause changes in the composition of the wine, both in the phenolic and aromatic compounds. In this work, we evaluated the influence of ultrasounds treatment (frequency: 50 KHz; ultrasonic power: 200 W; acoustic energy density: 0.02 W cm−3) on polyphenols content and colour parameters of a red wine (Vitis vinifera L. cv. Tempranillo) by comparing different ultrasound treatments, lees dosages and yeast species. In general, total anthocyanin content and total polyphenol index decreased in wines treated with ultrasounds and high lees dosage, and hue increased as a result of oxidation associated with the sonication process. Regarding the effect of the yeast species, anthocyanins loss was smaller in Saccharomyces cerevisiae and Schizosaccharomyces pombe.