Search results for "yeast"
showing 10 items of 792 documents
Biogenic amine production by lactic acid bacteria, acetic bacteria and yeast isolated from wine
2007
Abstract Biogenic amines are undesirable in all foods and beverages because if consumed at too high concentration, they may induce food-borne intoxications. The biogenic amine production by 155 strains of lactic acid bacteria, 40 strains of acetic bacteria and 36 strains of yeast isolated from wine were analysed in wine, grape must and synthetic media by HPLC. We did not observe biogenic amine production by acetic bacteria and yeast; however, we found production of histamine, tyramine, phenylethylamine and putrescine by LAB. A correlation of 100% was observed between biogenic amine production in synthetic medium and wine and between activity and presence of gene. With the results expose in …
Research report: Interactions between toxic fatty acids for yeasts and colloids, cellulose and yeast ghost using the equilibrium dialysis method in a…
1997
Abstract The capacity of different materials (yeast walls, colloids and cellulose) to bind octanoic acid and decanoic acid was investigated in a model wine. The interactions between these toxic fatty acids and the soluble or insoluble material was shown using the equilibrium dialysis method. Yeast walls adsorb decanoic acid and to a lesser extent octanoic acid which confirms previous results. In comparison, colloids from both grape or yeast weakly bind decanoic acid and do not significantly bind octanoic acid. No interactions between cellulose and fatty acid were observed. According to the yeast wall composition, lipids seem to play a key role for binding. With regards to our results, the e…
Hydrolysis and sorption by Saccharomyces cerevisiae strains of Chardonnay grape must glycosides during fermentation
2005
Abstract Different Saccharomyces cerevisiae strains were tested for their ability to hydrolyse glycosyl–glucose (G–G) compounds present in Chardonnay must during alcoholic fermentation. The determination of glycosyl–glucose during the course of the alcoholic fermentation of Chardonnay grape must revealed that S. cerevisiae is able to hydrolyse G–G during alcoholic fermentation in wine conditions. The extent of hydrolysis vary from 17 to 57% of the initial glycoside concentration. In order to confirm that decrease in G–G concentration during alcoholic fermentation is due to hydrolytic action and not to sorption phenomenon, in the first experiment, an analysis of the osidic part of Chardonnay…
Influence of yeast autolysis after alcoholic fermentation on the development of <em>Brettanomyces</em>/<em>Dekkera</em> in wi…
2001
<p style="text-align: justify;"><em>Brettanomyces</em>, a contaminant yeast, is relatively common in wines and mainly in red wines during barrel aging. The results presented here relate to the effects of yeast lees autolysis on the growth of <em>Brettanomyces</em>. Experiments were realised in a culture medium after alcoholic fermentation, in a hydroalcoholic wine-like solution and in a red wine. <em>Brettanomyces</em> was inoculated at low level : 10<sup>2</sup> cfu/ml and the growth was controlled by counting on agar appropriate medium. Yeast lees from <em>S. cerevisiae</em> were added to these media in the presence or abse…
Etude d'une microflore levurienne champenoise
1982
<p style="text-align: justify;">Pendant quatre années consécutives, on a suivi en Champagne, l'évolution de la microflore levurienne depuis la baie de raisin jusqu'au vin clair. Les résultats montrent une influence sensible sur la microflore, d'une part de certains traitements phytosanitaires et d'autre part des opérations liées à la vendange et au traitement des moûts. Grâce à un milieu de culture électif spécial, les auteurs ont amélioré la séparation des colonies de <em>S. cerevisiae</em> et de <em>S. bayanus</em>.</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">For four consecutive years the evolution of yea…
Modeling hexanal production in oxido-reducing conditions by the yeast Yarrowia lipolytica
2009
International audience; Hexanal produced by cells of a recombinant Yarrowia lipolytica yeast expressing the hydroperoxide lyase (HPL) from green bell pepper fruit was studied under oxido-reducing conditions using the reducing dithiotreitol and oxidizing potassium ferricyanide compounds. The combined effect of pH, linoleic acid 13-hydroperoxides concentration, temperature and oxido-reducing molecules on the hexanal production was studied. Significant positive effects for the hexanal production were found using high concentrations of hydroperoxides (100 mM, 30 g/L). Adding reducing molecules enhanced significantly hexanal production while the oxidizing molecules had an inhibitory effect. Comb…
Biosorption of nickel (II) and zinc (II) from aqueous solutions by the biomass of yeast Yarrowia lipolytica
2017
Abstract This study examined the biosorption process of Ni(II) and Zn(II) from an aqueous solution by dead biomass of Yarrowia lipolytica. Optimum biosorption conditions were determined as a function of pH, biomass dosage, contact time, and temperature. The biosorbent was characterized by FTIR, which indicated the participation of hydroxyl, carboxyl, amide and amine groups in the process of binding the metal ions. The results showed that the biosorption processes of both metal ions closely followed pseudo-second order kinetics. The equilibrium data of Ni(II) and Zn(II) ions at 20, 30 and 40°C fitted the Langmuir and Freundlich isotherm models. Langmuir isotherm provided a better fit to the …
Toxicity of fatty acid hydroperoxides towards Yarrowia lipolytica: Implication of their membrane fluidizing action
2007
Abstract Linoleic acid hydroperoxide (HPOD), substrate of hydroperoxide lyase, an enzyme of the lipoxygenase pathway, can be transformed into many aromatic compounds, the so-called “green notes”. The presence of linoleic acid hydroperoxide in the culture medium of Yarrowia lipolytica, the yeast expressing the cloned hydroperoxide lyase of green bell pepper, undoubtedly exerted an inhibition on the growth and a toxic effect with 90% of yeast cells died after 120 min of exposition in 100 mM HPOD solution. The increase in cell membrane fluidity evaluated by measuring fluorescence generalized polarization with the increasing concentration of HPOD in the medium confirmed the fluidizing action of…
Genetic and molecular basis of the aroma production in S. kudriavzevii, S. uvarum and S. cerevisiae
2016
En la presente tesis nos hemos centrado en el estudio del papel de las especies S. uvarum y S. kudriavzevii en la síntesis de aromas y como principal aplicación en la elaboración de vinos. En estudios anteriores, estas dos especies, estrechamente relacionadas con S.cerevisiae, mostraron diferencias notables durante la producción de alcoholes superiores y ésteres cuando se comparaban con S. cerevisiae (Gamero et al., 2013; Pérez-Torrado et al., 2015). Los alcoholes superiores y ésteres formados por las levaduras, son componentes claves en el sabor y el aroma de los productos fermentados. Tal y como hemos mencionado previamente, S. kudriavzevii y S. uvarum presentan diferencias muy significat…