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

Quality and Composition of Red Wine Fermented with Schizosaccharomyces pombe as Sole Fermentative Yeast, and in Mixed and Sequential Fermentations with Saccharomyces cerevisiae

U radu je ispitana fiziologija kvasca Schizosaccharomyces pombe (soj 938) upotrijebljenog za proizvodnju crnog vina. Provedeno je više tipova fermentacija: s kvascem Schizosaccharomyces pombe 938, s mješovitom kulturom kvasaca Sc. pombe i Saccharomyces cerevisiae 796, te fermentacija prvo s pomoću Sc. pombe, a zatim s pomoću S. cerevisiae. Za dodatnu su usporedbu provedene fermentacije samo s kvascem S. cerevisiae, za što je upotrijebljen komercijalni pripravak bakterija mliječne kiseline, koje su provele malolaktičnu fermentaciju po završetku alkoholne fermentacije. Za razliku od kvasca S. cerevisiae, kvasac Sc. pombe provodi maloalkoholnu fermentaciju, pri čemu se smanjuje koncentracija jabučne kiseline u vinu. Tijekom fermentacije praćeni su sljedeći parametri: relativna gustoća; koncentracija octene, jabučne i piruvatne kiseline; početne koncentracije amino dušika i uree; te pH-vrijednost mošteva. U svim fermentacijama u kojima je sudjelovao kvasac Sc. pombe 938 jabučna je kiselina (početne koncentracije od 5,5 g/L) gotovo potpuno upotrijebljena za rast kvasaca, a nastala je umjerena koncentracija octene kiseline (manja od 0,4 g/L). Udjel je uree u tim vinima bio deset puta manji nego u vinima fermentiranim samo s kvascem S. cerevisiae 796. Senzorska su se svojstva vina dobivenih različitim tipovima fermentacija bitno razlikovala. Vina fermentirana s pomoću kvasca Sc. pombe 938 imala su najbolju kakvoću i intenzitet arome, pa su dobila najbolje ocjene pri senzorskoj analizi uzoraka vina.This work examines the physiology of Schizosaccharomyces pombe (represented by strain 938) in the production of red wine, as the sole fermentative yeast, and in mixed and sequential fermentations with Saccharomyces cerevisiae 796. For further comparison, fermentations in which Saccharomyces cerevisiae was the sole fermentative yeast were also performed; in these fermentations a commercial lactic acid bacterium was used to perform malolactic fermentation once alcoholic fermentation was complete (unlike S. cerevisiae, the Sc. pombe performs maloalcoholic fermentation and therefore removes malic acid without such help). Relative density, acetic, malic and pyruvic acid concentrations, primary amino nitrogen and urea concentrations, and pH of the musts were measured over the entire fermentation period. In all fermentations in which Sc. pombe 938 was involved, nearly all the malic acid was consumed from an initial concentration of 5.5 g/L, and moderate acetic acid concentrations below 0.4 g/L were formed. The urea content of these wines was notably lower, showing a tenfold reduction when compared with those that were made with S. cerevisiae 796 alone. The sensorial properties of the different final wines varied widely. The wines fermented with Sc. pombe 938 had maximum aroma intensity and quality, and they were preferred by the tasters

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

Schizosaccharomyceswas initially considered as a spoilage yeast because of the production of undesirable metabolites such as acetic acid, hydrogen sulfide, or acetaldehyde, but it currently seems to be of great value in enology.o ced Nevertheless, Schizosaccharomyces can reduce all of the malic acid in must, leading to malolactic fermentation. Malolactic fermentation is a highly complicated process in enology and leads to a higher concentration of biogenic amines, so the use of Schizosaccharomyces pombe can be an excellent tool for assuring wine safety. Schizosaccharomyces also has much more potential than only reducing the malic acid content, such as increasing the level of pyruvic acid and thus the vinylphenolic pyranoanthocyanin content. Until now, few commercial strains have been available and little research on the selection of appropriate yeast strains with such potential has been conducted. In this study, selected and wild Sc. pombe strains were used along with a Saccharomyces cerevisiae strain to ferment red grape must. The results showed significant differences in several parameters including non-volatile and volatile compounds, anthocyanins, biogenic amines and sensory parameters

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

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

Use of Ultra-High Pressure Homogenization processing in winemaking:Control of microbial populations in grape musts and effects in sensory quality

Ultra-High Pressure Homogenization (UHPH) is a fast and efficient technique that can sterilizefluid foods at lowtemperatures or even under cooling conditions. A white must (Vitis viniferaL.) was processed at 300 MPa (inlettemperature 20 °C, in-valve temperature 98 °C, outlet temperature 25 °C, and time in valve 0.02 s) and theirperformance was compared with two untreated controls, a must that underwent a spontaneous fermentation(without SO2addition) and another must that was sulfited with 35 mg/L of total SO2and inoculated with thesameSaccharomyces cerevisiaeyeast as the UHPH-treated must. UHPH treatment led to the total elimination ofgrape microorganisms considering an initial population of 1 × 106CFU/mL in average of wild yeasts and fungiin must, and approximately 7 × 103CFU/mL of background bacteria. In a parallel assay, UHPH-processed mustwithout yeast inoculation showed absence of fermentation for eight days at 18 °C. The musts treated with UHPHshowed a lighter appearance (10%) before fermentation compared to the control. The triangular test verified theexistence of sensory differences between the wines obtained and the preference tests showed that the judgesfound the wine obtained from the UHPH-treated must more fruity (3.5/5 compared with 1.5–2 in controls) andwith better aroma.Industrial relevance:UHPH is an interesting way to process the must before fermentation allowing the reductionof sulfite addition while controlling wild and spoilage microorganisms.info:eu-repo/semantics/acceptedVersio

Optical and AFM microscopy of grape juices treated with UHPH: Effects of microstructure and nanostructure

UHPH treatment of Vitis vinifera must for winemaking leads to fragmentation of colloidal particles into smaller structures. The shear and fracture forces experienced by grape juice during valve pressurization are sufficient to reduce the particle size of grape juice to below 500 nm. As a result, the applied force can disrupt bacterial and yeast cell structures, altering or breaking down proteins, polysaccharides and enzymes. This effect is not observed for low molecular weight compounds such as monomeric pigments and phenolic structures, varietal aroma precursors, fermentable sugars, etc. Treated and untreated samples can be compared using optical and atomic force microscopy. Optical microscopy images show reduction or elimination of bacteria and yeast and changes in microstructure. On the other hand, in addition to describing topography in the nanometer range, AFM can also measure particles in comparison to other techniques such as laser diffraction (LD). This work contributes to the characterization and better understanding of the effects of UHPH on grape juice for winemaking

Use of red grape juice (concentrated and treated by UHPH) as a base to produce isotonic drinks

The physical-chemical composition, sensory characteristics, and nutritional value of the grape juice can provide sports drink (isotonic beverage) with antioxidant compounds that complement the beneficial effect of these drinks to the rehydration and replacement of minerals and carbohydrates, during physical activity. Grape juice contains mainly water, sugars, organic acids, and phenolic compounds. By diluting the sugar content of the must to 40-50 g/L, it will allow us to obtain a drink with beneficial properties for health, avoiding the addition of sweeteners. Phenolic compounds play an important role in the prevention of various diseases through their biological activities related to antioxidant, anti-inflammatory, anticancer, anti-aging, antimicrobial and cardioprotective properties. Several studies have shown that grape juice allows to improve the performance of the activity, protect against oxidative damage, and reduce inflammation during, sports activities. The polyphenolic substances present in grape musts provide sensory characteristics of interest, mainly color and aroma, important indicators for consumers when choosing this type of beverage. The anthocyanin content of musts from red varieties, gives the drink a more natural and attractive character for the consumer without the use of synthetic dyes. It is important to recognize the demand of consumers for new innovative, and healthy products, so we focus on the development of a natural, functional drink using red grape musts as a base (concentrated or treated with UHPH) as a source of polyphenols and sugars, showing interesting organoleptic properties without chemical additives, and that allows to replenish electrolytes and energy

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

SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome

The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at first patient’s hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confirmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log10 copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n = 85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (≥ 7.35 log10 copies/mL, p = 0.003) and second tertile (≥ 8.27 log10 copies/mL, p = 0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the final multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age ≥ 70 years, SpO2, neutrophils > 7.5 × 103/µL, lactate dehydrogenase ≥ 300 U/L, and C-reactive protein ≥ 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome