Search results for "Fermentation"
showing 10 items of 746 documents
Maintenance of Wine-Associated Microorganisms
2008
A great variety of microorganisms growing on grapes, in must, or in wine have been isolated, which also have an influence on wine quality. They belong to acidtolerant microorganisms such as lactic acid bacteria, acetic acid bacteria, and yeasts. On grapes also molds can be found. The most important species for conversion of must into wine are the yeast Saccharomyces cerevisiae and the lactic acid bacterium Oenococcus oeni, which perform alcoholic and malolactic fermentation, respectively. Both species are used as starter cultures. A variety of techniques and media are available for the enrichment, culture, and preservation of these microorganisms. For selected species culture and preservati…
Effect of ethanol on the ability of Oenococcus oeni to remove ochratoxin A in synthetic wine-like media
2010
The study focused on the changes in bacterial population, malolactic fermentation and ochratoxin A (OTA) levels in cultures of Oenococcus oeni performed in synthetic medium supplemented with ethanol and OTA. Growth was better in cultures containing 5% ethanol and was not observed in cultures containing 15% ethanol. The OTA removal ability of O. oeni depended on ethanol and initial OTA levels. The highest toxin removal percentage was observed in cultures containing 5% ethanol and 2 μg OTA/l. In ethanol-containing medium part of OTA was not sorbed by O. oeni and remained in the liquid medium. Thus, it cannot efficiently eliminate OTA in acidic ethanol-containing beverages, such as wine. The e…
Evolution of anthocyanin profile from grape to wine
2010
<p style="text-align: justify;"><strong>Aims</strong>: This study aimed at acquiring knowledge of the evolution of anthocyanins from grape to wine and the possibility of deducing the varietal origin of a wine from its anthocyanin profile.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The anthocyanin « fingerprint », or profile, of a series of autochthonous Sicilian accessions and their respective young wines was determined by HPLC-DAD in 2008. Data were evaluated by taking into account the evolution of the percentages of side-ring dioxygenated and tri-oxygenated anthocyanins, the ratio between acetylated and p-coumaroylate…
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
2014
The present work was undertaken to evaluate the effect of natural wine making on the microbial and chemical composition of Marsala base wine. To this purpose, a large-scale vinification process of Grillo grape cultivar was monitored from the grape harvest to the final product. Total yeasts (TY) showed a rapid increase after must pressings and reached values that were almost identical to those registered during conventional wine makings. Lactic acid bacteria (LAB) were registered at the highest levels simultaneous to those of yeast growth at the beginning of the process. Saccharomyces cerevisiae was the species found at the highest concentrations in all samples analysed. Several strains (n =…
Yeasts and Sparkling Wine Production
2019
Sparkling wines are produced in many different countries. Among sparkling wines, some are produced from Charmat or bottle fermentation. In this chapter, the practical methods and principles of producing quality sparkling wine is given in details including each step of the production from viticultural parameters, base wine production up to secondary fermentation. After the second fermentation in bottle, the wine is aged on lees. During aging, yeast autolysis occurred. The mechanisms of yeast autolysis and the compounds released are presented. The consequences of yeast autolysis on wine quality are detailed. Finally the riddling and disgorging operation are presented
Rational selection of non-Saccharomyces wine yeasts for mixed starters based on ester formation and enological traits
2008
Thirty-eight yeast strains belonging to the genera Candida, Hanseniaspora, Pichia, Torulaspora and Zygosaccharomyces were screened for ester formation on synthetic microbiological medium. The genera Hanseniaspora and Pichia stood out as the best acetate ester producers. Based on the ester profile Hanseniaspora guilliermondii 11027 and 11102, Hanseniaspora osmophila 1471 and Pichia membranifaciens 10113 and 10550 were selected for further characterization of enological traits. When growing on must H. osmophila 1471, which displayed a glucophilic nature and was able to consume more than 90% of initial must sugars, produced levels of acetic acid, medium chain fatty acids and ethyl acetate, wit…
Molecular identification and characterization of wine yeasts isolated from Tenerife (Canary Island, Spain)
2007
Aims: The present study was aimed at the identification, differentiation and characterization of indigenous yeasts isolated from Tenerife vineyards (viticulture region that has never been characterized before). Microbiota were studied from 14 samples taken during fermentations carried out in the 2002 vintage, from 11 wineries belonging to five wine regions on Tenerife Island. Methods and Results: Yeasts’ strains were identified and characterized through restriction analysis of the 5·8S-internal transcribed spacer region and the mitochondrial DNA. At the beginning of alcoholic fermentation, 26 yeast species were found, where 14 species were present in significant frequencies in only one sa…
Wine-making with protection of must against oxidation in a warm, semi-arid terroir
2016
In order to defend varietal aromas from oxidation before alcoholic fermentation, two musts were prepared from white grapes pre-cooled and added with ascorbic acid and solid CO2 (trial ACO2) or SO2 (trial BSO2). Experiments were performed with grapes of a white grape variety indigenous to western Sicily, the wines from which, obtained by vinification of musts protected from oxidation and poor in copper, as previously proven, have aroma descriptors ascribed to passion fruit and grapefruit skin. The smaller content in flavanols in the ACO2 trial, demonstrated that the use of solid CO2, instead of SO2, reduced the extraction of such polyphenols from grape solids. The higher content in hydroxyci…
Effect of micro-oxygenation on the evolution of aromatic compounds in wines: Malolactic fermentation and ageing in wood
2009
Abstract The effect of micro-oxygenation on the aromas of two varietal wines (Tempranillo and Cabernet Sauvignon) when alcoholic fermentation is complete was examined. Several factors, such as whether malolactic fermentation (MLF) took place in barrels or stainless steel vats and ageing time in oak barrels, were taken into account. Major aroma components were studied using GC-FID and minor compounds were studied by GC–MS analysis before and after MLF and after 4 and 8 months of maturation in oak barrels. Sensorial analysis was performed to describe and quantify the different wine notes. Micro-oxygenation affects different compounds but the effect depends to a great extent on the grape varie…
Metabolism of Sugars and Organic Acids by Lactic Acid Bacteria from Wine and Must
2008
Heterofermentative lactic acid bacteria (LAB) which are common in plant associated environments are found also in grape must and wine. In this environment specific strains predominate which are adapted to the low pH and high alcohol contents. Must and wine harbour the strictly heterofermentative Oenococcus oeni, Lactobacillus hilgardii and Lactobacillus brevis, and the facultatively heterofermentative Lactobacillus plantarum and Lactobacillus pentosus (Rodas et al. 2005). In addition homofermentative lactic acid bacteria of the Pediococcus group are able to grow in wine and must, but are normally found at low cell densities. The growth of lactic acid bacteria in wine depends largely on suga…