Search results for "Lees"
showing 10 items of 17 documents
Immobilisation of yeasts on oak chips or cellulose powder for use in bottle-fermented sparkling wine
2019
[EN] Sparkling wine production comprises two successive fermentations performed by Sacharomyces cerevisiae strains. This research aimed to: develop yeast immobilisation processes on two wine-compatible supports; study the effects of yeast type (IOC 18-2007 and 55A) and the immobilisation support type (oak chips and cellulose powder) on the fermentation kinetics, the deposition rate of lees and the volatile composition of the finished sparkling wine; compare the fermentation parameters of the wines inoculated with immobilised or non-immobilised cells. Proper immobilisation of yeast on oak chips and cellulose powder was demonstrated by electron microscopy. Total sugar consumption occurred in …
Sorption of wine volatile phenols by yeast lees
2005
The capacity of Saccharomyces cerevisiae yeast lees to sorb 4-ethylguaiacol and 4-ethylphenol was investigated in a synthetic medium and in wine. Active dried yeast was more effective when volatile phenols were diluted in red wine. Partition coefficients between wine model solution and wine yeast lees were determined and compared with those measured for dried active yeast. They showed a larger affinity of volatile phenols for wine yeast lees than for dried active yeast. The effect of yeast lees on volatile phenol sorption was sensitive to yeast autolysis level and to physicochemical parameters, such as ethanol content, temperature and pH. These results could be applied in the technology of …
Yeast autolysis in sparkling wine – a review
2006
Sparkling wine produced by the traditional methode champenoise requires a second in-bottle alcoholic fermentation of a base wine, leading to the sparkling wine. This second fermentation is followed by prolonged ageing in contact with yeast cells (lees). The autolysis of yeast occurs during the ageing of sparkling wines. During this process, the yeast releases different compounds that modify the organoleptic properties of the wine. The ageing period is required to give these wines their roundness and characteristic aroma and flavour. Autolysis products also influence the foaming properties of sparkling wine. Yeast autolysis is characterised by the hydrolysis of intracellular biopolymers by y…
Natural oxygenation of Champagne wine during ageing on lees: A metabolomics picture of hormesis
2016
International audience; The oxygenation of Champagne wine after 4 and 6 years of aging on lees in bottle was investigated by FTICR-MS and UPLC-Q-TOF-MS. Three levels of permeability were considered for the stoppers, ranging from 0.2 to 1.8 mg/L/year of oxygen transfer rate. Our results confirmed a good repeatability of ultrahigh resolution FTICR-MS, both in terms of m/z and coefficient of variation of peak intensities among biological replicates. Vintages appeared to be the most discriminated features, and metabolite annotations suggested that the oldest wines (2006) were characterized by a higher sensitivity towards oxygenation. Within each vintage, the oxygenation mechanisms appeared to b…
Ultrastructural changes of sparkling wine lees during long-term aging in real enological conditions.
2012
Ultrastructural changes of lees of three series of sparkling wines produced using the traditional method during long-term aging (4 years) were assessed by high-pressure freezing in combination with transmission electron microscopy. The stratified structure of the cell wall disappeared throughout aging. After 18 months, the microfibrous material of the cell wall appeared more diffuse and the amorphous midzone of the inner wall layer was progressively degraded. From 30 months onward, the cell wall consisted of a tangled structure of fibers. In spite of these changes, the cell wall of yeasts remained unbroken at 48 months of wine aging. Cell membrane breakage was observed for the first time in…
La circulation de l'information dans la presse des expulsés
2016
This article is aimed at analysing the circulation of the information flow in the press of expellees. From press releases of the Landsmannschaften, of the BdV or the political parties, over travel journals from local associations or texts from readers, content of journals is rarely written from the editors of newspapers. In this niche in the medias placed out of the mass medias, the interactions between the different titles are unavoidable, they are even desirable to support this economically weak sector. A case study will show how the circulation of information allows enrichment of the publications but also how if it leads to a retreat of this press section.
Surface properties of Saccharomyces cerevisiae lees during sparkling wine ageing and their effect on flocculation
2009
Cell surface properties were determined for the first time for lees of Saccharomyces cerevisiae, and they proved to be significantly dependent on the time of sparkling wine ageing on lees. Cell surface hydrophobicity decreased from approximately 44% to 11% of affinity to hexadecane. Electron acceptor capacity (calculated as % affinity to ethyl acetate-% affinity to decane) increased from approximately -27% to 10 % and zeta potential from approximately -4 to 6mV. Mannoproteins are released from the external cell wall layer during the autolytic process, as confirmed by TOF-SIMS analysis of the cell wall chemical composition. This could explain the modifications of lees cell surface properties…
Non-Thermal Ultrasonic Extraction of Polyphenolic Compounds from Red Wine Lees
2020
This study presents the results of conventional aqueous (CE) and non-conventional ultrasound-assisted (UAE) extractions of polyphenolic compounds from lees extracts of red wine varieties (Merlot and Vranac). The effect of ultrasound extraction time (t, s), and amplitude (A,%) from a 400 W ultrasound processor with different ultrasonic probes diameters (Ds, mm) on the amount and profile of polyphenolic compounds in the obtained extracts was investigated and compared to CE. The optimal conditions resulting in maximum extraction of phenolic compounds were: Probe diameter of 22 mm, amplitude 90% and extraction time for Vranac wine lees 1500 s and for Merlot wine lees extraction time of 1361 s. …
Yeasts and Sparkling Wine Production
2019
Sparkling wines are produced in many different countries. Among sparkling wines, some are produced from Charmat or bottle fermentation. In this chapter, the practical methods and principles of producing quality sparkling wine is given in details including each step of the production from viticultural parameters, base wine production up to secondary fermentation. After the second fermentation in bottle, the wine is aged on lees. During aging, yeast autolysis occurred. The mechanisms of yeast autolysis and the compounds released are presented. The consequences of yeast autolysis on wine quality are detailed. Finally the riddling and disgorging operation are presented
Le rôle déterminant de la presse dans la vie des expulsés allemands
2016
This article focuses on the identity of the German expellees after World War II through the study of one of their publications, the Grafschafter Bote. For this population who is spread geographically all over Germany, the newspapers published by numerous associations have contributed to the creation and the maintaining of a collective identity able to sustain its position in the new German state. These newspapers still exist today and contribute to the strengthening of a particular identity.