Search results for "wine"
showing 10 items of 1468 documents
Monitoring of mixed culture fermentations
2022
Current and future constraints linked to climate change and evolution of wine consumer demand are prompting the winemaking industry to consider adopting new practices to address the technical challenges resulting from this context. These challenges include the need to maintain a constant alcohol level despite increased sugar contents in the must, and to seek a wider diversity of aromatic profiles, while maintaining acceptable reproducibility.Fermentations with addition of non-Saccharomyces yeasts to the Saccharomyces cerevisiae species traditionally used to conduct alcoholic fermentation seem to be an interesting alternative to achieve these objectives. However, the numerous interactions be…
The hidden face of expertise! Representations and descriptions of wines by different groups of experts in a vineyard in full evolution : the Beaujola…
2022
The Beaujolais vineyard is today in full evolution thanks to a policy of upgrading and moving upmarket. This evolution leads to the development of new mentions within the vineyard. This evolution impacts the Beaujolais wines but also the wine experts who are in the heart of making, selling and promoting these wines. Wine expertise has been studied extensively over the past twenty years. Most studies have focused on experts as a unified group versus novices to understand the effect of expertise on the knowledge and abilities of experts. However, it appears that within this unity, there are several types of experts with different backgrounds, knowledge, experiences, and professions: wine make…
Combining Olfactory and Gustatory Clues in the Judgment of Aging Potential of Red Wine by Wine Professionals
2010
International audience; The study was aimed at determining the relative importance of olfactory and gustatory information for the vin de garde concept, which refers to wine that is intended for aging. First, the study investigated how olfactory information contributed to the assessment of the aging potential of young wine. Burgundy wine professionals categorized 26 red wines (vintage 2005) according to their aging potential in two experimental conditions: orthonasal evaluation and overall evaluation. Second, the aromatic notes associated with wines perceived with an aging potential were examined. A trained descriptive panel described the odor of the 26 red wines to determine whether the win…
Study of biogenic amines metabolism in wine lactic acid bacteria
2011
Biogenic amines are indesirable compounds found in fermented products like wine. Lactic acid bacteria from wine, including Oenococcus oeni, the main actor of malolactic fermentation, are able to produce these molecules from nitrogenous precursors. In order to limited biogenic amines accumulation, it is necessary to understand the role of this production by strains responsible for the synthesis of these metabolites in food. That is why the European BiamFood project was put in place. Along my thesis, molecular tools were developed in order to mutate O. oeni genes (encoding decarboxylases), and to express genes of interest. Genetic clusters hdc from L. higardii and odc from O. oeni, responsibl…
Contribution to the molecular study of the oxidative stability of white wines of Burgundy
2019
In order to understand and control the aging of wines, particularly white wines, it is necessary to deepen our knowledge about the physico-chemical mechanisms of oxidation related to oxygenation processes. For this, it is important to have tools to quantify the antioxidant capacity of white wines, and to identify the compoiunds involved, in order to anticipate the aging ability of a wine.In this study, analyzes of the antioxidant capacity by DPPH and Electron Paramagnetic Resonance (EPR) were carried out on a large number of wines during aging and from several vintages, in parallel with metabolomic analyzes, mainly carried out by Liquid Chromatography Coupled to Mass Spectrometry (UPLC-Q-TO…
Study of nitrogen requirements of non-Saccharomyces yeasts during winemaking : impact on sequential fermentations
2019
Study of the interaction between the non-Saccharomyces yeast and Saccharomyces cerevisiae. This study aims to describe changes in the flavor profile of the wine on one hand and reducing percentage of alcohol on the other hand. For this, control of non-Saccharomyces yeast is required. Thus, the main aromatic molecules must be measured according to the conditions of cultures (pure culture - sequential culture) and their effects on the organoleptic properties will be evaluated. In parallel, their sugar, nitrogen, oxygen and vitamins requirements will be determined to decrease the percentage of alcohol in the wine.
Biodiversité fongique du raisin au vin : impact de l'activité anthropique
2016
The effects of different anthropogenic activities (vineyard, winery) on fungal populations from grape to wine were studied. To characterize these effects, it was necessary to access to the overall diversity of populations (pyrosequencing and spectroscopy FT-IR) but also to intra-specific diversity (FT-IR). Spectroscopy FT-IR has been validated for their ability to characterize the global population and to discriminate the strains for three species of non-Saccharomyces yeasts (NS). For the first time, it is shown that the grape berry is a limited source for NS yeasts while the winery seems to be a significant source; the air is an important vector for dissemination of these yeasts. In additi…
Le goût moisi-terreux du vin : contribution à la caractérisation cinétique et métabolique des moisissures associées à ce défaut organoleptique
2011
Some microorganisms that co-exist on the grapevine may have beneficial effects on the quality of wine whereas others may be at the origin of organoleptic deviations. In the last decade, several mouldy or earthy odors have been highlighted in various wine regions from France. (-)-geosmin was found to be the major compound responsible for this deviation, along with Botrytis cinerea and fungi belonging to the genus Penicillium, since they were frequently isolated from “earthy-musty” odor grapes. The extent of damage on the quality of wines, motivated our study on the caracterisation of grape rot fungi. First of all, the microflora of grapes from Burgundy vineyards was identified (morphological…
Contamination of rapeseed harvest by volunteers of other varieties : a study of intergenotypic competition
2004
Rapeseed volunteers in rapeseed crops can cause contamination in harvest through pollen and seeds. The aim of the study was to predict pollen and seed production by volunteers in winter rapeseed crops according to the genotypes of the crop and the volunteers. Firstly an experimental analysis of intraspecific competition was carried out in 2000 and 2001 on two and six genotypes, respectively. The main competition period begins with vegetation onset and affects pollen and seed production of the volunteers. Relations between density, height, yield and number of flowers were developed based on results from experiments and literature. Knowing the densities and heights of volunteers and crop on t…
Amino acids role in biogenic amine production by Oenococcus Oeni
2013
In wine biogenic amines (BA) are mainly of microbial origin, Oenococcus oeni, the mainresponsible for malolactic fermentation, has been identified as a BA producer from nitrogenprecursors. Oenococcus oeni possess numerous amino acid auxotrophies that are precursors ofbiogenic amines. No study has been done so far to look at the relationship betweenauxotrophy for amino acids precursors of BA and the level of BA in the medium. In order todo so, 80 Oenococcus oeni strains were isolated from red wines. The detection of genesencoding the different decarboxylases responsible for BA synthesis has been realised. Inparallel, the auxotrophy for the four amino acids (Arg, Tyr, His, Phe) precursors of …