Consecutive alcoholic fermentations of white grape musts with yeasts immobilized on grape skins : effect of biocatalyst storage and SO2 concentration on wine characteristics

Abstract Saccharomyces cerevisiae yeasts, immobilized by natural adsorption on grape skins, were used to carry out the alcoholic fermentation step of a winemaking process. The viability of the immobilized cells was evaluated by the implementation of 7 successive fermentations of a white grape must containing 30 mg/L of SO2. The time to complete alcoholic fermentation, the physicochemical characteristics of the produced wines (ethanol, glycerol, organic acids, volatile compounds, color) and sensory properties were evaluated. A traditional fermentation with free cells was used as control. Three other fermentations were conducted after storage of the immobilized biocatalyst (30 d, 4 oC), the first one in the same conditions of the earlier assays, and the other two with higher amounts of SO2 (60 mg/L, 90 mg/L). Wines produced with immobilized cells presented physicochemical and sensory characteristics similar to those traditionally produced with free cells. After three consecutive fermentations, chromatic characteristics became similar to those of traditional wines, but the fermentation time had been reduced from 7 d to 4 d. The fermentative process and the characteristics of the produced wines were not significantly affected by the use of higher amounts of SO2. Immobilized biocatalysts could be stored at least one month without losing its activity.Zlatina Genisheva gratefully acknowledges FCT (Contract/grant number: SFRH/BD/48186/2009) and the Project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER, for the financial support of this work

Патон Борис Євгенович

Патон Борис Євгенович — видатний вітчизняний учений, всесвітньо відомий спеціаліст в галузі зварювання, металознавства, металургії, спорудження відповідальних інженерних конструкцій, автор багатьох фундаментальних ре зультатів і створених на їх основі нових технологій і відповідного обладнання. У 1951 р. його обрано членом-кореспондентом, в 1958 р. — дійсним членом (академіком) Академії наук УРСР, з 1962 р. він — її президент

Influence of fining agents on the sensorial characteristics and volatile composition of mead

Mead, one of the oldest fermented drinks, is derived from the fermentation of diluted honey by yeasts. In the context of wine production, several procedures are applied to stabilize the beverage and to improve its organoleptic properties. This study aims to evaluate the impact of adding fining agents on the production of mead. In general, the best results were obtained for the samples containing just one fining agent instead of two combined. However, the best performance was obtained for the combined fining agents (bentonite + gelatine + egg albumin). Tannins decreased significantly the content of volatile compounds. On the other hand, silica appears to be the best fining agent, resulting in the lowest loss of volatile compounds. Thirty-six volatile compounds were determined by gas chromatographflame ionization detector and gas chromatographymass spectrometry, including alcohols (42.5%), carbonyl compounds (40.4%), acetates (14.4%) and esters (1.8%). Eleven volatile compounds had odour activity values >1, representing those with a major impact on the aroma of mead. Significant differences (p 0.05) were observed for remaining compounds.A. Pascoal would like to thank Fundação para a Ciência e Tecnologia (FCT), Programa Operacional Pontencial Humano and European Union for his postdoctoral grant (SFRH/BPD/91380/2012). The authors are grateful to FCT, Portugal and Fundo Europeu de Desenvolvimento Regional (FEDER) under Programme PT2020 for financial support to Centro de Investigação de Montanha (CIMO) (UID/AGR/00690/2013). This work was supported by the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the European Regional Development Fund (ERDF) through the COMPETE2020 – Programa Operacional Competitividade e Internacionalização.info:eu-repo/semantics/publishedVersio

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine-making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol,glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO2 were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations.Zlatina Genisheva gratefully acknowledges FCT (contract/grant number: SFRH/BD/48186/2009) for financial support of this work. The authors would like to thank Divisao de Vitivinicultura Direccao Regional de Agricultura e Pescas do Norte for providing the grape pomace for yeast immobilization and the must to conduct alcoholic fermentations. The authors thank also Professor Joao Linhares for help in computing the CIELab coordinates

Use of Schizosaccharomyces strains for wine fermentation? Effect on the wine composition and food safety

Schizosaccharomyceswas initially considered as a spoilage yeast because of the production of undesirable metabolites such as acetic acid, hydrogen sulfide, or acetaldehyde, but it currently seems to be of great value in enology.o ced Nevertheless, Schizosaccharomyces can reduce all of the malic acid in must, leading to malolactic fermentation. Malolactic fermentation is a highly complicated process in enology and leads to a higher concentration of biogenic amines, so the use of Schizosaccharomyces pombe can be an excellent tool for assuring wine safety. Schizosaccharomyces also has much more potential than only reducing the malic acid content, such as increasing the level of pyruvic acid and thus the vinylphenolic pyranoanthocyanin content. Until now, few commercial strains have been available and little research on the selection of appropriate yeast strains with such potential has been conducted. In this study, selected and wild Sc. pombe strains were used along with a Saccharomyces cerevisiae strain to ferment red grape must. The results showed significant differences in several parameters including non-volatile and volatile compounds, anthocyanins, biogenic amines and sensory parameters

Ecophysiological modeling of grapevine water stress in Burgundy terroirs by a machine-learning approach.

13 pagesInternational audienceIn a climate change scenario, successful modeling of the relationships between plant-soil-meteorology is crucial for a sustainable agricultural production, especially for perennial crops. Grapevines (Vitis vinifera L. cv Chardonnay) located in eight experimental plots (Burgundy, France) along a hillslope were monitored weekly for 3 years for leaf water potentials, both at predawn (Ψpd) and at midday (Ψstem). The water stress experienced by grapevine was modeled as a function of meteorological data (minimum and maximum temperature, rainfall) and soil characteristics (soil texture, gravel content, slope) by a gradient boosting machine. Model performance was assessed by comparison with carbon isotope discrimination (δ13C) of grape sugars at harvest and by the use of a test-set. The developed models reached outstanding prediction performance (RMSE < 0.08 MPa for Ψstem and < 0.06 MPa for Ψpd), comparable to measurement accuracy. Model predictions at a daily time step improved correlation with δ13C data, respect to the observed trend at a weekly time scale. The role of each predictor in these models was described in order to understand how temperature, rainfall, soil texture, gravel content and slope affect the grapevine water status in the studied context. This work proposes a straight-forward strategy to simulate plant water stress in field condition, at a local scale; to investigate ecological relationships in the vineyard and adapt cultural practices to future conditions

Mead production: effect of nitrogen supplementation on growth, fermentation profile and aroma formation by yeasts in mead fermentation

Mead is an alcoholic beverage, produced since ancient times, resulting from an alcoholic fermentation of diluted honey by yeasts. When it is produced in a traditional manner, mead producers can encounter several problems related to a lack of es-sential nutrients, such as available nitrogen. Thus, the aim of this study was to evaluate the effect of nitrogen addition to honey-must on the fermentation performance of two Saccharomyces cerevisiae wine yeasts, QA23 and ICV D47, as well as on the mead composition and production of volatile aroma compounds. A portion of honey-must was supplemented with diammonium phosphate (DAP) to achieve the nitrogen concentration required by yeast to complete alcoholic fermentation. The supplementation with DAP reduced the fermentation length to around 7 days, but not all sugars were fully consumed, suggesting that other factors could be interfering with yeast growth. For both yeasts the specic growth rate and nal bio-mass were higher in musts supplemented with DAP. Mead nal composition was similar under the two experimental condi-tions. Analysis of the volatile prole revealed that the concentrations of the volatile fatty acids and volatile phenols were higher in meads supplemented with DAP. The concentrations of ethyl hexanoate, ethyl octanoate and isoamyl acetate were above their perception threshold and were higher in meads supplemented with DAP, which could contribute to the enhance-ment of the fruity character. This study could be useful for the optimization of mead production and quality improvement.The research presented in this paper was partially funded by the Fundacao para a Ciencia e Tecnologia (FCT) (project PTDC/AGR-ALI/68284/2006). A.P.P. is a recipient of a PhD grant from the FCT (SFRH/BD/45820/2008)

Early leaf removal impact on volatile composition of Tempranillo wines

Early defoliation is a very innovative technique in viticulture used for yield management. The effects of early leaf removal performed manually and mechanically at two different phenological stages, pre-bloom and fruit set, on the volatile composition of Tempranillo (Vitis vinifera L.) wines were studied. Volatiles were identified and quantified by gas chromatography Early leaf removal only modified the total concentrations of C6 compounds and acetates, whereas total alcohols, esters, volatile acids and terpenes remained generally unaffected. Early defoliation induced a significant reduction in C6 compounds and increased the concentrations of acetates in Tempranillo wines. An effect of timing (pre-bloom vs fruit set) alone was observed for all acetates analysed. Regarding the method of defoliation (manual vs mechanical), significant differences in some ethyl ester (ethyl-2-methylbutyrate and ethyl octanoate) and volatile acid concentrations were observed among treatments. Ethyl octanoate, 2-phenylethyl acetate, 3-methylbutyl acetate and hexanoic acid, with OAV (odour activity value) > 1 and mainly fruity and floral odour descriptors, showed higher levels after early defoliation treatments compared with non-defoliated vines. Principal component analysis illustrated the difference in wines from defoliated and non-defoliated treatments based on their volatile composition. It can be concluded that early leaf removal significantly modified the wine aroma compounds, increasing or decreasing several of these compounds.We thank the Agencia de Desarrollo Economico de La Rioja (ADER) and the Ministerio de Ciencia e Innovacion for their financial support (ADER-2006-I-ID-00157 and AGL2007-60378 respectively). We would also like to thank the Agrupacion de Bodegas Centenarias y Tradicionales de Rioja (ABC) and New Holland for their assistance and help. Dr Vilanova is grateful to the 'Isidro Parga Pondal' programme financed by the Xunta de Galicia (Spain)

Genetic diversity, linkage disequilibrium and power of a large grapevine (Vitis vinifera L) diversity panel newly designed for association studies

UMR-AGAP Equipe DAVV (Diversité, adaptation et amélioration de la vigne) ; équipe ID (Intégration de Données)International audienceAbstractBackgroundAs for many crops, new high-quality grapevine varieties requiring less pesticide and adapted to climate change are needed. In perennial species, breeding is a long process which can be speeded up by gaining knowledge about quantitative trait loci linked to agronomic traits variation. However, due to the long juvenile period of these species, establishing numerous highly recombinant populations for high resolution mapping is both costly and time-consuming. Genome wide association studies in germplasm panels is an alternative method of choice, since it allows identifying the main quantitative trait loci with high resolution by exploiting past recombination events between cultivars. Such studies require adequate panel design to represent most of the available genetic and phenotypic diversity. Assessing linkage disequilibrium extent and panel power is also needed to determine the marker density required for association studies.ResultsStarting from the largest grapevine collection worldwide maintained in Vassal (France), we designed a diversity panel of 279 cultivars with limited relatedness, reflecting the low structuration in three genetic pools resulting from different uses (table vs wine) and geographical origin (East vs West), and including the major founders of modern cultivars. With 20 simple sequence repeat markers and five quantitative traits, we showed that our panel adequately captured most of the genetic and phenotypic diversity existing within the entire Vassal collection. To assess linkage disequilibrium extent and panel power, we genotyped single nucleotide polymorphisms: 372 over four genomic regions and 129 distributed over the whole genome. Linkage disequilibrium, measured by correlation corrected for kinship, reached 0.2 for a physical distance between 9 and 458 Kb depending on genetic pool and genomic region, with varying size of linkage disequilibrium blocks. This panel achieved reasonable power to detect associations between traits with high broad-sense heritability (> 0.7) and causal loci with intermediate allelic frequency and strong effect (explaining > 10 % of total variance).ConclusionsOur association panel constitutes a new, highly valuable resource for genetic association studies in grapevine, and deserves dissemination to diverse field and greenhouse trials to gain more insight into the genetic control of many agronomic traits and their interaction with the environment