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Artigues-près-Bordeaux, France

Renault P.,CNRS Oenologie Research Unit | Coulon J.,Biolaffort | de Revel G.,CNRS Oenologie Research Unit | de Revel G.,French National Institute for Agricultural Research | And 3 more authors.
International Journal of Food Microbiology | Year: 2015

The aim of this work was to study ester formation and the aromatic impact of Torulaspora delbrueckii when used in association with Saccharomyces cerevisiae during the alcoholic fermentation of must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae.Our results showed that mixed inoculations allowed the increase, in comparison to S. cerevisiae pure culture, of some esters specifically produced by T. delbrueckii and significantly correlated to the maximal T. delbrueckii population reached in mixed cultures. Thus, ethyl propanoate, ethyl isobutanoate and ethyl dihydrocinnamate were considered as activity markers of T. delbrueckii. On the other hand, isobutyl acetate and isoamyl acetate concentrations were systematically increased during mixed inoculations although not correlated with the development of either species but were rather due to positive interactions between these species.Favoring T. delbrueckii development when performing sequential inoculation enhanced the concentration of esters linked to T. delbrueckii activity. On the contrary, simultaneous inoculation restricted the growth of T. delbrueckii, limiting the production of its activity markers, but involved a very important production of numerous esters due to more important positive interactions between species. These results suggest that the ester concentrations enhancement via interactions during mixed modalities was due to S. cerevisiae production in response to the presence of T. delbrueckii.Finally, sensory analyses showed that mixed inoculations between T. delbrueckii and S. cerevisiae allowed to enhance the complexity and fruity notes of wine in comparison to S. cerevisiae pure culture. Furthermore, the higher levels of ethyl propanoate, ethyl isobutanoate, ethyl dihydrocinnamate and isobutyl acetate in mixed wines were found responsible for the increase of fruitiness and complexity. © 2015 Elsevier B.V.

Rinaldi A.,University of Naples Federico II | Iturmendi N.,Biolaffort | Jourdes M.,University of Bordeaux Segalen | Teissedre P.-L.,University of Bordeaux Segalen | Moio L.,University of Naples Federico II
LWT - Food Science and Technology | Year: 2015

A simulated maceration was carried out with skins or seeds of Aglianico, Merlot and Cabernet Sauvignon grape cultivars in order to study the entity of the transfer of tannins from grape to wine. The structural characteristics of skins and seeds extracts (native tannins) and corresponding wine-like solutions (macerated tannins) were analysed by phloroglucinolysis. Their potential astringency was evaluated according to the reactivity towards salivary proteins by the Saliva Precipitation Index (SPI). From grape to wine-like solution, the transfer of structural characteristics varied differently for skins and seeds. A significant influence of extraction method and grape variety was also stated, principally as regard the percentage of prodelphinidins (%P) for skins, and of galloylation (%G) for seeds. For some parameters that were able to differentiate grapes through the maceration process, a cultivar effect emerged. Reactivity of tannins also differed, but not for seeds. For Aglianico native and macerated tannins, the highest in SPIs, seeds monomers and oligomers were quantified by HPLC/MS. Principal Component Analysis (PCA) allowed to reveal the structural characteristics mainly associated with the reactivity of tannins towards salivary proteins. The proanthocyanidins content and the %G increased potential astringency, while it was reduced by the %P. © 2015 Elsevier Ltd.

Rinaldi A.,University of Naples Federico II | Iturmendi N.,Biolaffort | Gambuti A.,University of Naples Federico II | Jourdes M.,University of Bordeaux Segalen | And 2 more authors.
Electrophoresis | Year: 2014

Saliva is a biological fluid with a multifunctional role that makes it interesting in terms of research and diagnostic possibilities. In food research, human saliva represented a useful tool by which we measure the tactile sensation elicited by polyphenol-rich beverages called astringency. A method based on SDS-PAGE analysis of saliva before and after the binding reaction with wine polyphenols has been successfully used in previous studies for measuring wine astringency by means of the saliva precipitation index. In this work, chip electrophoresis was used alternatively to SDS-PAGE and results were compared. Chip electrophoresis provides a very good reproducibility for wine and grape astringency. Moreover, this approach is much faster than the conventional SDS-PAGE method requiring several hours for an analysis. Another advantage over traditional gel is lower sample and reagent volume requirements, as well as the lower and less toxic wastes, contributing benefits to health and environment. The application of this novel method allowed, using the principal component analysis, to distinguish grapes and wines according to the saliva precipitation index and structural characteristics determined by the phoroglucinolysis analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thibon C.,French National Institute for Agricultural Research | Thibon C.,University of Bordeaux 1 | Bocker C.,University of Bordeaux 1 | Shinkaruk S.,University of Bordeaux 1 | And 3 more authors.
Food Chemistry | Year: 2016

Two main precursors (S-3-(hexan-1-ol)-l-cysteine and S-3-(hexan-1-ol)-l-glutathione) of 3-sulfanylhexanol (3SH, formerly named 3-mercaptohexanol) have been identified so far in grape juice but a correlation between precursor concentrations in grape juices and 3SH concentrations in wines is not always observed. This suggests that there may be other compounds associated with the aromatic potential. In this work, S-3-(hexanal)-glutathione (Glut-3SH-Al) and its bisulfite (Glut-3SH-SO3) adduct were identified in Sauvignon blanc grape juice by liquid chromatography coupled to Fourier transform mass spectrometry experiments. A partial purification of the compounds was carried out by Medium Pressure Liquid Chromatography (MPLC) on the reverse phase using 5 L of grape juice. The addition of synthetized Glut-3SH-Al and Glut-3SH-SO3 in the synthetic medium induced a significant release of 3SH after fermentation. Moreover, we demonstrate that Glut-3SH-Al and its bisulfite adduct are present in grape juice and could be considered as new direct 3SH precursors with molar conversion yields close to 0.4%. © 2015 Published by Elsevier Ltd.

Renault P.,CNRS Oenologie Research Unit | Coulon J.,Biolaffort | Moine V.,Biolaffort | Thibon C.,CNRS Oenologie Research Unit | And 2 more authors.
Frontiers in Microbiology | Year: 2016

The aim of this work was to study the volatile thiol productions of two industrial strains of Torulaspora delbrueckii and Saccharomyces cerevisiae during alcoholic fermentation (AF) of Sauvignon Blanc must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae. The results confirmed the inability of T. delbrueckii to release 4-methyl-4-sulfanylpentan-2-one (4MSP) and its low capacity to produce 3-sulfanylhexyl acetate (3SHA), as already reported in previous studies. A synergistic interaction was observed between the two species, resulting in higher levels of 3SH (3-sulfanylhexan-1-ol) and its acetate when S. cerevisiae was inoculated 24 h after T. delbrueckii, compared to the pure cultures. To elucidate the nature of the interactions between these two species, the yeast population kinetics were examined and monitored, as well as the production of 3SH, its acetate and their related non-odorous precursors: Glut-3SH (glutathionylated conjugate precursor) and Cys-3SH (cysteinylated conjugate precursor). For the first time, it was suggested that, unlike S. cerevisiae, which is able to metabolize the two precursor forms, T. delbrueckii was only able to metabolize the glutathionylated precursor. Consequently, the presence of T. delbrueckii during mixed fermentation led to an increase in Glut-3SH degradation and Cys-3SH production. This overproduction was dependent on the T. delbrueckii biomass. In sequential culture, thus favoring T. delbrueckii development, the higher availability of Cys-3SH throughout AF resulted in more abundant 3SH and 3SHA production by S. cerevisiae. © 2016 Renault, Coulon, Moine, Thibon and Bely.

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