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

Estudio microbiológico del proceso madurativo del queso de Mahón : elaboración de un "Starter" para su fabricación a partir de la leche pasterizada

Tesis Univ. Complutense de Madrid.Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEProQuestpu

Wine Spoilage Yeasts: Control Strategy

Traditionally in winemaking, sulphur dioxide (SO2) is chemically the most widely used for microflora control as antimicrobial preservative. Other tested compounds for selective yeast control are sorbic and benzoic acids. Herein, we discuss the effectiveness and the application of traditional and novel treatments and biotechnologies for chemical and biological control of wine spoilage yeasts. The versatility of the killer toxins and the antimicrobial properties of natural compounds such as carvacrol, essential oils and bioactive peptides will be considered. Some of the wine spoilage yeasts that are intended to control belong to the genera Zygosaccharomyces, Saccharomycodes and Dekkera/Brettanomyces, but also the non-Saccharomyces yeasts species dominating the first phase of fermentation (Hanseniaspora uvarum, Hansenula anomala, Metschnikowia pulcherrima, Wickerhamomyces anomalus) and some others, such as Schizosaccharomyces pombe, depending on the kind of wine to be produced

The oenological interest of fumaric acid: Stop malolactic fermentation and preserve the freshness of wines

ABSTRACT One of the problems related to the increase in average temperatures in the wine-growing regions is the lower accumulation of organic acids in the berries. Wine freshness depends to a great extent on its acidity. Herein, the effectiveness of fumaric acid to inhibit malolactic fermentation or to stop it once initiated is evaluated in order to preserve the malic acid content. Different doses of fumaric acid and SO2 were tested. The ability of these compounds to inhibit bacterial development and stop the malic acid degradation was testedonaredwineofthevarietyVitisviniferaL.cv.Tempranillowhosemalicacidcontentwassetat1.5g/L. The control wine inoculated with 6 log CFU/mL of Oenococcus oeni finished the malolactic fermentation in 12 days. However, the use of doses equal to or greater than 300mg/L of fumaric acid delayed the onset of malolactic fermentation for more than 50 days with little degradation of malic acid. In addition, fumaric acid proved to be effective in stopping malolactic fermentation already started where the bacterial count was 7 log CFU/mL. Fumaric acid can be considered as a potent inhibitor of malolactic fermentation

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