Search results for "fermentation"
showing 10 items of 746 documents
The effect of glycerol on the perceived aroma of a model wine and a white wine
2001
Abstract Glycerol is one of the most abundant components of wine. In dry wines its concentration is only exceeded by water and ethanol. Several studies have been carried out on the effects of glycerol on mouthfeel, but little attention has been given to glycero–flavour interactions. Consequently, here we have turned our attention to the aroma perception. Purge and Trap analysis and sensory measurements were used to investigate the modifications in volatility of aroma compounds in model solutions and white wine according to their glycerol concentration. In water, the amount of aroma compounds released was not affected by the presence of glycerol concentrations ranging from 5 to 50 g/L. The a…
Genomic and Proteomic Analysis of Wine Yeasts
2011
Publisher Summary Saccharomyces cerevisiae is the main microorganism involved in wine fermentation. It has been used as a model organism in molecular biology for many years and is the only wine yeast species for which abundant genomic and proteomic information is available. Most of the techniques currently used in functional genomics and proteomics were initially developed in this yeast. The fact that S. cerevisiae was the first microorganism to be widely used in the development of genome technology allowed other phylogenetically related yeasts to be analyzed subsequently in global sequencing projects, and the use of comparative genomics has since led to important conclusions regarding gene…
Vitamins in wine: Which, what for, and how much?
2021
Vitamins are essential compounds to yeasts, and notably in winemaking contexts. Vitamins are involved in numerous yeast metabolic pathways, including those of amino acids, fatty acids, and alcohols, which suggests their notable implication in fermentation courses, as well as in the development of aromatic compounds in wines. Although they are major components in the course of those microbial processes, their significance and impact have not been extensively studied in the context of winemaking and wine products, as most of the studies focusing on the subject in the past decades have relied on relatively insensitive and imprecise analytical methods. Therefore, this review provides an extensi…
Fermentative stress adaptation of hybrids within the Saccharomyces sensu stricto complex.
2008
Along the fermentation process yeasts are affected by a succession of stress conditions that affect their viability and fermentation efficiency. Among the stress conditions the most relevant are high sugar concentration and low pH in musts, temperature and, as fermentation progresses, ethanol accumulation. Nowadays, due to the demanding nature of modern winemaking practices and sophisticated wine markets, there is an ever-growing search for particular wine yeast strains possessing a wide range of optimized, improved or novel enological characteristics. Traditionally, the species S. cerevisiae and S. bayanus within the Saccharomyces sensu stricto species are considered some of the most impor…
Induction of stress proteins inLeuconostoc oenos to perform direct inoculation of wine
1994
The enhancement or induction of the protein synthesis was clearly observed in cells ofL. oenos labeled with35S for five proteins during heat shock at 42°C and acid shock at pH 3. Furthermore, no stress protein was induced after exposure ofL. oenos to ethanol shock 10% (v/v). Moreover, survival ofL. oenos in wine and ability to perform alolactic fermentation was improved after direct inoculation when cells were pretreated at 42°C.
Improvement of volatile composition of wines by controlled addition of malolactic bacteria
1999
The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as a control. Malolactic fermentation and evolution of non volatile compounds were followed by HPLC and after the depletion of the malic acid present in wine the volatile compounds were extracted and analyzed by gas chromatography with flame ionization and mass spectrometry. Wines which had undergone the MLF s…
Identification of a yeast strain as a potential stuck wine fermentation restarter: a kinetic characterization
2013
Restarter yeast strains are used to consume residual sugar (mainly fructose) in stuck wine fermentations. Forty-three yeast strains were evaluated initially. Strain ITD-00068 showed the highest values for the maximum growth rate, maximum fructose consumption rate, and maximum ethanol production rate (0.143, 0.268, and 0.231 h−1, respectively). Therefore, it was selected for further molecular and kinetic analyses. RFLP analysis identified this isolate as Saccharomyces cerevisiae. Strain ITD-00068 consumed 100% and 36% of the fructose present (at 20°C and 30°C, respectively), when cultured in medium with 12% (v/v) ethanol. The fructose consumption rate was reduced by 97% at 30°C, when ethanol…
Screening of Hanseniaspora Strains for the Production of Enzymes with Potential Interest for Winemaking
2015
Some non-Saccharomyces yeasts, including Hanseniaspora, participate in the first stages of wine fermentation. Besides their importance in the wine production process some of these yeasts have been described to be potential producers of hydrolytic enzymes to industrial level. In this work, we pretend to evaluate the technological abilities of the Hanseniaspora strains deposited in the Spanish Type Culture Collection (CECT). First of all, we considered verification of the correct identification of the strains using several miniaturized biochemical systems and molecular techniques (PCR, RFLP and sequencing of the ribosomal D1/D2 region). The results allowed us to verify the correct adscription…
Stress response and expression patterns in wine fermentations of yeast genes induced at the diauxic shift
2000
During wine fermentation yeasts quickly reach a stationary phase, where cells are metabolically active by consuming sugars present in grape must. It is, consequently, of great interest at this stage to identify suitable gene promoters that may be used to induce the expression of genes with enological applications. With this aim, we have studied a group of genes showing an induction peak at the diauxic shift, and possessing stress response elements (STRE) at their promoters. We have determined their induction levels under individualized stress conditions, such as carbon source starvation or high salt concentrations. In all the cases studied, the activation and/or basal transcription are depe…
A comparative study of the wine fermentation performance of Saccharomyces paradoxus under different nitrogen concentrations and glucose/fructose rati…
2010
8 pages, 1 figure, 4 tables.-- Online version published: May 2009.-- The definitive version is available at www3.interscience.wiley.com