Search results for "fermentation"
showing 10 items of 746 documents
Selection and molecular characterization of wine yeasts isolated from the ‘El Penedès’ area (Spain)
2000
Abstract A study of the microbiota present during the wine fermentation of five grape varieties from the ‘El Penedes’ area (Spain) was carried out to select autochthonous yeast strains for industrial wine production. In this study we identified members of the genera Candida, Dekkera, Hanseniaspora, Kluyveromyces, Torulaspora, Zygosaccharomyces and Saccharomyces in wine fermentation microbiota. Strains of Saccharomyces cerevisiae, as responsible agents of the alcoholic fermentation, were considered for a selection protocol. In this work we applied different enological criteria for selection, but previously we have characterized and differentiated Saccharomyces isolates by molecular methods t…
Amino acids and volatile compounds in wines from Cabernet Sauvignon and Tempranillo varieties subjected to malolactic fermentation in barrels
2012
The aim of the present paper is to compare the behaviour of industrial lactic bacteria and indigenous bacteria of the cellar when malolactic fermentation was carried out in barrels. The effects of these bacteria on the concentration of metabolised amino acids during malolactic fermentation and on the composition of volatile compounds both before and after malolactic fermentation are studied. The experiment was performed with wines of the Tempranillo and Cabernet Sauvignon varieties. An analysis has been made of the easily extractable volatile compounds of the wood and the compounds from the grapes, and the action of the yeasts during the alcoholic fermentation. Acetoin and diacetyl decreas…
Aroma compounds in wine as influenced by apiculate yeasts
1996
Aroma compounds of wines resulting from fermentation of sterile grape musts from Monastrell variety inoculated with pure and mixed cultures of apiculate and Saccharomyces yeasts, were isolated and analyzed by gas chromatography with flame ionization and mass spectrometry. Samples fermented with mixed cultures produced a higher concentration of selected compounds and higher total amounts of alcohols and acids, in contrast with wines produced with pure cultures of Saccharomyces spp. Apiculate yeasts are important in the chemical composition and quality of wine.
Surface properties of Saccharomyces cerevisiae lees during sparkling wine ageing and their effect on flocculation
2009
Cell surface properties were determined for the first time for lees of Saccharomyces cerevisiae, and they proved to be significantly dependent on the time of sparkling wine ageing on lees. Cell surface hydrophobicity decreased from approximately 44% to 11% of affinity to hexadecane. Electron acceptor capacity (calculated as % affinity to ethyl acetate-% affinity to decane) increased from approximately -27% to 10 % and zeta potential from approximately -4 to 6mV. Mannoproteins are released from the external cell wall layer during the autolytic process, as confirmed by TOF-SIMS analysis of the cell wall chemical composition. This could explain the modifications of lees cell surface properties…
Saccharomyces Yeasts I
2011
Publisher Summary This chapter discusses the microbiological aspects of saccharomyces yeasts in wine production. Yeasts, which play a central role in the winemaking process, are unicellular fungi that reproduce by budding. Most yeast belongs to the phylum Ascomycota on the basis of their sexual development. The selection of wine yeasts with specific genetic markers provides a system for the precise monitoring of the growth of particular strains during fermentation. Analyses of this type have shown that fermentation is driven mainly by inoculated yeasts, although these sometimes become only partially established. The growth of the natural flora is not completely suppressed during the initial…
NAD(P)H regeneration is the key for heterolactic fermentation of hexoses in Oenococcus oeni
2002
Oenococcus oeni (formerly Leuconostoc oenos) can perform malolactic fermentation, converting L-malate to L-lactate and carbon dioxide, in wines. The energy and redox potential required to support the growth of the micro-organism are supplied mainly by the consumption of carbohydrates via the heterolactic pathway. In the first steps of hexose metabolism two molecules of NAD(P)(+) are consumed, which must be regenerated in later reactions. The aim of this work was to test if aerobic growth of O. oeni promotes higher cell yields than anaerobic conditions, as has been shown for other lactic acid bacteria. O. oeni M42 was found to grow poorly under aerobic conditions with glucose as the only car…
Adaptive evolution of wine yeast.
2003
Abstract Alcoholic fermentation is one of the main phases in wine production. It is usually conducted by yeasts belonging to the species Saccharomyces cerevisiae. Industrial S. cerevisiae strains are highly specialized organisms, which have evolved to utilize to their full potential the different environments or ecological niches. So, during the alcoholic fermentation, the yeast has been adapted to different kinds of stress conditions; this adaptation is call “domestication”. In this review, we describe the different mechanisms involved in the adaptive evolution of wine yeast strains.
Authentication and identification of Saccharomyces cerevisiae‘flor’ yeast races involved in sherry ageing
2004
Yeasts involved in velum formation during biological ageing of sherry wine have to date been classified into four races of Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis, rouxii) according to their abilities to ferment different sugars. It has been proposed that race succession during biological ageing is essential for the development of the organoleptical properties of sherry wines. In this work we studied the physiological characteristics, the molecular differentiation and the phylogenetic relationships of the four races employing type and reference strains from culture collections and natural environments. Using restriction analysis of the ribosomal region that includes th…
Isolating Wine Yeasts that are Specific to the Apold Region and Identifying them through RFLP Genetic Methods
2015
The present study aims at isolating, identifying and selecting autochthonous wine yeast strains with a view to establish a crop bank specific to the Apold area. 569 wine yeast strains were isolated during the alcoholic fermentation of must from the Apold area, 458 were identified through cultural methods and with the help of the API 20 C AUX test (Biomeriux, France). Six yeast strains (A87, A169, A296, A314, A132 and A413) were genetically identified through the PCR-ITS RFLP method of the 5.8S-ITS segment; the resulting four strains were Saccharomyces cerevisiae - A87, A169, A296, A314 - and two Saccharomyces bayanus strains - A132 și A413. The strains we identified constitute a base for t…
Differences in the glucose and fructose consumption profiles in diverse Saccharomyces wine species and their hybrids during grape juice fermentation
2009
7 pages, 4 figures, 5 tables.