1,721,074 research outputs found
Idrolisi di precursori d’aroma glicosilati nel corso della fermentazione malolattica
No full textThe ability of four commercial preparations of Oenococcus oeni lactic acid bacteria (EQ 54, Lalvin O.S.U., Uvaferm Alpha, and Lalvin 31) to hydrolyse wine aroma precursors was evaluated by measuring the concentration of free and bound aroma compounds at the end of malolactic fermentation carried out in model wines containing a mixture of glycosides extracted from Muscat wine. At pH 3,4 there was a decrease in glycosylated compounds matched by a concomitant increase in free forms in all starter cultures tested. When malolactic fermentation was carried out at pH 3,2 a significant decrease in the ability to hydrolyse aroma precursors was observed for two of the cultures tested (Uvaferm Alpha and Lalvin 31). Large differences in the extent of hydrolysis and in the specificity of this activity towards specific aroma precursors were observed, and appeared related to the chemical structure of the aglycon as well as to individual characteristics of each starter culture. The amounts of glycosylated aroma compounds released during malolactic fermentation suggest that O. oeni can alter the sensory characteristics of wine through the hydrolysis of aroma precursors
Changes in the concentration of yeast-derived volatile compounds of red wine during malolactic fermentation with four commercial starter cultures of Oenococcus oeni
No full textThe effects of malolactic fermentation (MLF) on the concentration of volatile compounds released by yeasts during the production of red wine were investigated by inoculation with four commercial starters of Oenococcus oeni. Volatile compounds in wine at the end of MLF were extracted, analyzed by GC-MS and GC, and compared with those extracted form a noninoculated reference sample. Several esters known to play a role in the aroma profile of red wine, such as C4-C8 ethyl fatty acid esters and 3-methylbutyl acetate, were found to increase with MLF, and their final concentration was dependent on the bacterial starter employed for the induction of MLF. The overall increase of ethyl fatty acid esters was generally larger than the one observed for acetate esters. Ethyl lactate, 3-hydroxybutanoate, 2-phenylethanol, methionol, and γ-butyrolactone were also increased by bacterial metabolism. The impact of MLF on other volatiles or red wine, including several higher alcohols, fatty acids, and nitrogen compounds, was generally negligibl
Changes in the concentration of yeast-derived volatile compounds of red wine during malolactic fermentation with four commercial starter cultures of Oenococcus oeni
No full textThe effects of malolactic fermentation (MLF) on the concentration of volatile compounds released by yeasts during the production of red wine were investigated by inoculation with four commercial starters of Oenococcus oeni. Volatile compounds in wine at the end of MLF were extracted, analyzed by GC-MS and GC, and compared with those extracted form a noninoculated reference sample. Several esters known to play a role in the aroma profile of red wine, such as C4-C8 ethyl fatty acid esters and 3-methylbutyl acetate, were found to increase with MLF, and their final concentration was dependent on the bacterial starter employed for the induction of MLF. The overall increase of ethyl fatty acid esters was generally larger than the one observed for acetate esters. Ethyl lactate, 3-hydroxybutanoate, 2-phenylethanol, methionol, and γ-butyrolactone were also increased by bacterial metabolism. The impact of MLF on other volatiles or red wine, including several higher alcohols, fatty acids, and nitrogen compounds, was generally negligibl
The influenceof malolactic fermentation and “Oenococcus oeni” strain on glycosidc aroma precursors and related volatile compounds of red wine
No full textThe influenceof malolactic fermentation and “Oenococcus oeni” strain on glycosidc aroma precursors and related volatile compounds of red wine
No full textFermentative and post-fermentative oxygenation of Corvina red wine: influence on phenolic and volatile composition, colour and wine oxidative response
No full textBackground: During the production of red wine, moderate uptake of oxygen in the post-fermentative phase helps the stabilization of colour and the decrease of astringent tannins. However, the influence of oxygen uptake during the fermentative phase in must has not been completely investigated. In this study we evaluated the effect of controlled oxygen supply during fermentation-maceration of Corvina grapes on colour characteristics, tannins, volatile compounds, acetaldehyde production and oxidative stability of the finished wine. Results: Oxygen supply during fermentation improved the formations of stable pigments of Corvina wines due to the higher production of acetaldehyde. However, in wines treated with oxygen a lower production of fruity esters by yeasts was observed. Wines obtained from higher oxygen exposure during fermentation-maceration showed reduced ability to react with oxygen during storage. Conclusions: Fermentative and post-fermentative oxygenation should be considered as a technological approach for modifying colour composition and stability, as well as oxidative behaviour of wine during aging. © 2020 Society of Chemical Industry
Hydrolysis of grape aroma precursors during malolactic fermentation with four commercial starter cultures of Oenococcus oeni.
No full textHydrolysis and transformation of grape glycosidically bound volatile compounds during fermentation with three saccharomyces yeast strains
No full textCopyright © 2006 American Chemical SocietyMaurizio Ugliano, Eveline J. Bartowsky, Jane McCarthy, Luigi Moio and Paul A. Henschk
Assessment of yeasts for apple juice fermentation and production of cider volatile compounds
No full textAt present, yeasts suitable for apple juice fermentation to produce cider have received scarce attention with respect to wine yeasts. In this study, Saccharomyces and non-Saccharomyces strains were investigated for their capacity to ferment apple juice and to influence the volatile compound production in cider. In a first fermentation trial, seven out of 18 yeasts, belonging to Saccharomyces cerevisiae, S. uvarum, Torulaspora delbrueckii, Hanseniaspora osmophila, H. uvarum, Starmerella bacillaris and Zygosaccharomyces bailii, were selected according to their fermentative performance. The effects of these strains on the volatile composition of cider, produced in a second apple fermentation trial, were then evaluated. Significant differences on the production of alcohols, esters and fatty acids were observed. Large amounts of 2-phenylethanol were found in S. uvarum cider. Hanseniaspora uvarum was the greatest producer of hexyl and isoamyl acetate among non-Saccharomyces yeasts. Ciders were well discriminated by principal component analysis. This study provides insights into the actual capacity to produce volatile compounds that the different yeast species that could be used in single or mixed apple juice fermentation for cider production
Hydrolysis and transformation of grape glycosidically bound volatile compounds during fermentation with three Saccharomyces yeast strains
No full textThe ability of three Saccharomyces wine yeasts (S. cerevisiae AWRI 838, S. cerevisiae AWRI 1537, and S. bayanus AWRI 1375) to liberate volatile compounds from sugar-bound aroma precursors was investigated using synthetic and grape glycosides under different experimental conditions. In model systems involving the incubation of yeast cells with either synthetic or grape-derived glycosides under conditions more favorable for glycosidase activities and less favorable for acid-catalyzed hydrolysis (pH 5.0 and 30°C), all yeast strains studied proved to be capable of hydrolyzing glycosides, with S. bayanus AWRI 1375 displaying greater hydrolytic activity than S. cerevisiae AWRI 838 and AWRI 1537. During the fermentation of a chemically defined grape juice-like medium containing glycosidic precursors extracted from Vitis vinifera cv. White Frontignac (synonym Muscat à Petit Grains Blanc), all yeasts promoted a significant hydrolysis of different precursors, which varied according to the chemical structures of both the sugar and the aglycon moieties, as determined by GC-MS analysis of trifluoroacetylated derivatives. Hydrolysis of the White Frontignac derived glycosidic precursors during fermentation resulted in the release of monoterepene alcohols, terpene oxides, terpene diols, and 3-oxo-α-ionol, demonstrating the significant potential of these yeast strains to contribute to wine varietal volatile composition during alcoholic fermentatio
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