12 research outputs found
Influence of Yeasts in Wine Colour
Colour is the first impression that the consumer receives from wine and it influences the taste. Colour gives an idea about wine quality, age, oxidation and structure, so it has an important repercussion on the consumer perception of wine. Yeasts promote the formation of stable pigments by the production and release of fermentative metabolites affecting the formation of vitisin A and B type pyranoanthocyanins. The hydrox- and ycinnamate decarboxylase activity showed by some yeast strains produces highly reactive vinylphenols stimulating the formation of vinylphenolic pyranoanthocyanins from grape anthocyanin precursors during fermentation. Some yeasts also influence the formation of polymeric pigments by unclear mechanisms that can include the production of linking molecules such as acetaldehyde. Grape anthocyanins adsorbed in yeast cell walls during fermentation are removed from wine after racking processes affecting final pigment content. Moreover, the intensive use of non‐Saccharomyces yeasts in current oenology makes it interesting to assess the effect of new species in the improvement of wine colour
Strategies to Improve the Freshness in Wines from Warm Areas
Trends in wine consumption are continuously changing. The latest in style is fresh wine with moderate alcohol content, high acidity, and primary aromas reminiscent of grapes, whereas certain fermentative volatiles may also influence the freshness of the wine. In addition, the effects of climate change on the composition of the grapes (high sugar content and low acidity) are adverse for the quality of the wine, also considering the microbiological stability. Herein, different strategies aiming at improving wine freshness are presented, and their performance in winemaking is discussed: among them, the addition of organic acids able to inhibit malolactic fermentation such as fumaric acid; the use of acidifying yeasts for alcoholic fermentation, such as Lachancea thermotolerans; and the selection of non-Saccharomyces yeasts with β-glucosidase activity in order to release terpene glycosides present in the must
Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO<sub>2</sub>
This chapter reviews the main non-thermal technologies with application in enology and their impact in: the extraction of phenolic compounds from grapes, the elimination of indigenous microorganisms, and the subsequent effect in SO2 reduction. The technologies are physical processes with null or low repercussion in temperature and therefore gentle with sensory quality of grapes. High hydrostatic pressure (HHP), ultra high pressure homogenization (UHPH), pulsed electric fields (PEFs), electron-beam irradiation (eBeam), ultrasound (US), and pulsed light (PL) have interesting advantages and some drawbacks that are extensively reviewed highlighting the potential applications in current technology
Improving the implantation of non-Saccharomyces yeasts in winemaking by UHPH processing
The use of unconventional yeasts, also called non-Saccharomyces yeasts, is a hot topic in current enology due to the improvement that can be produced in the sensory profile during fermentation. However, the use of these yeasts have problems due to difficulties in the implantation and competition with wild Saccharomyces yeasts. Ultra-High Pressure Homogenization (UHPH) has demonstrated to be a powerful tool to eliminate microorganisms in grape must, specially yeast and bacteria even at low in-valve temperatures. UHPH can be considered a non-thermal technology with protective effect on sensitive molecules as terpenes and anthocyanins. The preprocessing of must by UHPH leaves it free of yeast with an optimal sensory quality, being this a perfect situation to inoculate non-Saccharomyces yeasts. We have fermented UHPH musts and controls with several non-Saccharomyces species (Lachancea thermotolerans, Metschnikowia pulcherrima, Torulaspora delbrueckii, Hanseniaspora vineae), reaching in most of the UHPH treatments better implantations of the inoculated yeasts and a complete elimination of wild yeasts. The impact of the UHPH treatment is a better expression of the metabolic and enzymatic activities of the non-Saccharomyces yeasts. That effect enhances the sensory quality and facilitates the use of non-Saccharomyces yeasts at industrial scale
Influence of Saccharomyces and non-Saccharomyces Yeasts in the Formation of Pyranoanthocyanins and Polymeric Pigments during Red Wine Making
Yeast are able to modulate many sensory parameters of wines during red must fermentation. The effect on color and on the formation of derived pigments during fermentation has been studied thoroughly since the 90s. Yeast can increase grape anthocyanin’s color by acidification by hyperchromic effect (increase of flavylium molecules). Recent studies with non-Saccharomyces species, as Lachancea thermotolerans, described the intense effect of some strains on anthocyanin’s color, and subsequent, stability, by strongly reducing wine’s pH during fermentation. Moreover, selected yeast strains of Saccharomyces have been shown to release metabolites such as pyruvic acid or acetaldehyde that promote the formation of vitisin A and B pyranoanthocyanins during must fermentation. Schizosaccharomyces pombe, because of its specific metabolism, can produce higher concentrations of pyruvate, which enhances the formation of vitisin A-type derivatives. The hydroxycinnamate decarboxylase activity that some Saccharomyces strains express during fermentation also promotes the formation of vinylphenolic derivatives. Some non-Saccharomyces species, such as S. pombe or P. guilliermondii can also improve the production of these derivatives compared to selected strains of Saccharomyces cerevisiae. Lastly, some yeasts are also able to modulate the formations of polymeric pigments between grape anthocyanins and flavonoids, such as catechins and procyanidins
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
Grape Processing by High Hydrostatic Pressure: Effect on Microbial Populations, Phenol Extraction and Wine Quality
© 2014, Springer Science+Business Media New York. Vitis vinifera (variety Tempranillo) grapes were subjected to high hydrostatic pressure (HHP) treatments of 200, 400 and 550 MPa for 10 min, and its effect on microbial populations, phenol extraction and wine quality was examined. At ≥400 MPa, the wild yeast population was strongly reduced from 104 to <10 cfu/ml. Bacteria showed greater resistance, and a residual load remained even after the treatment at 550 MPa. The extraction of phenolic compounds from the HHP-treated grapes was improved, with higher concentrations of total phenols obtained compared to crushing alone. Anthocyanin extraction was also increased, producing wines with better colour intensity. These wines also had higher methanol and ethanol contents and returned higher aromatic quality and colour scores. The HHP treatment of grapes may assist in the use of yeast starters, increase phenol extraction from grape skins and improve wine quality.This work was funded by the Ministerio de Economía y Competitividad (AGL2013-40503-R).Peer Reviewe