Macrowine 2021
IVES 9 IVES Conference Series 9 Interactions of wine polyphenols with dead or living Saccharomyces cerevisiae Yeast Cells and Cell Walls: polyphenol location by microscopy

Interactions of wine polyphenols with dead or living Saccharomyces cerevisiae Yeast Cells and Cell Walls: polyphenol location by microscopy

Abstract

Tannin, anthocyanins and their reaction products play a major role in the quality of red wines. They contribute to their sensory characteristics, particularly colour and astringency. Grape tannins and anthocyanins are extracted during red wine fermentation. However, their concentration and composition change over time, due to their strong chemical reactivity1. It is also well known that yeasts influence the wine phenolic content, either through the release of metabolites involved in the formation of derived pigments1, or through polyphenol adsorption2,3. Up to now, this adsorption has mainly been attributed to cell walls, though it has been supposed that small tannin dimers and trimers could enter the periplasmic space through the wall pores and interact with the plasma membrane4. Interactions between polyphenols and inactivated yeast cells or cell walls obtained from an enological commercial strain were studied first by means of adsorption isotherms in a model wine-like solution5. The framework of this study was the aging of red wines. Polyphenols were skin and seed tannins, and a pool of polyphenols purified from a red wine (Merlot). Results evidenced a high capacity of whole cells to irreversibly adsorb grape and wine tannins whereas only weak interactions were observed for cell walls. This point was quite unexpected considering literature and raised the question of the part played by cell walls in the yeast ability to fix wine polyphenols. In the present work, polyphenol location after their interactions with inactivated yeast cells or cell walls was studied by means of transmission electron microscopy, light epifluorescence and confocal microscopy. Microscopy observations evidenced that if tannins interact with cell walls, and especially cell wall mannoproteins, they mostly diffuse freely through the cell wall and plasma membrane of dead cells to interact with their cytoplasmic components. This raised the question of yeast interactions with polyphenols in the case of living cells. The study was thus extended and interactions studied during fermentation, at different stages. The impact of polyphenols on fermentation kinetic and yeast growth rate were determined. In our experimental conditions, the exponential phase of the fermentation and the yeast growth rate were affected by polyphenols. Confocal microscopy observations allowed evidencing the diffusion of polyphenols in living cells. These results demonstrate that interactions between yeast cells and polyphenols are not limited to cell walls. They also involve cytoplasmic components and may influence yeast metabolism.

Litterature cited: 1.Fulcrand et al. (2006), Am. J. Enol. Vitic., 57(3), 289. 2.Morata et al. (2003), J. Agric. Food Chem., 51, 4084 3.Mazauric et al. (2006). J. Agric. Food Chem.,54, 3876 4.Marquez et al. (2009), J. Agric. Food Chem., 57, 8026 5.Mekoue et al. (2015), J. Agric. Food Chem, 63, 660. 6.Mekoue et al. (2015), J. Agric. Food Chem, 63, 7539

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Article

Authors

Julie Mekoue Nguela*, Aude Vernhet, Jean-Marc Brillouet, Nathalie Sieczkowski

*INRA/SUPAGRO

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Development and validation of a standardized oxidation assay for the accurate measurement of the ability of different wines to form “de novo” oxidation-related aldehydes

From the standpoint of wine aroma oxidation there are two effects observed: aroma degradation of oxygen sensitive compounds (polyfunctional mercaptans) and the appearance of new substances with high aromatic power (acetaldehyde, methional, phenylacetaldehyde, sotolon, alkenals, isobutanal and 2, 3-metylbutanals) (1-5). According to our experience, Strecker aldehydes are compounds with highest sensory relevance in the oxidative degradation of many wines (5-7).

The effect of Nitrogen and Sulphur foliar applications in hot climates

ine nitrogen deficiency can negatively influence the aroma profile and ageing potential of white wines. Canopy management can alter vine microclimate, affect the nitrogen availability and influence the response of leaf senescence. Increasing the nitrogen availability to vines can increase the Yeast Assimilable Nitrogen (YAN) levels in harvested fruit and wine. Studies show that foliar nitrogen and sulphur applications at véraison, on low YAN Sauvignon blanc grapes have an effect on the level of amino acids (Jreij et al. 2009) and on S-containing compounds such as glutathione and thiols (Lacroux et al. 2008), which in turn can influence the formation of major volatiles and the aroma profile of the wine.

Ageing of sweet wines: oxygen evolution according to bung and barrel type

Barrel ageing is a crucial step in the wine process because it allows many changes to the wine as enrichment, colour stabilization, clarification and also a slow oxygenation. Effects of the oak barrel have to be known to prevent oxidation of the wine. The type of bung used during ageing is also a parameter to consider. Ageing sweet wines in barrel is a real challenge. These wines may need some oxygen at the beginning of ageing but they should be protected at the end of their maturation, to avoid oxidation.

Using combinations of recombinant pectinases to elucidate the deconstruction of the polysaccharide‐rich grape cell wall during winemaking

The effectiveness of enzyme-mediated maceration processes in red winemaking relies on a clear picture of the target (berry cell wall structure) to achieve the optimum combination of specific enzymes to be used. However, we lack the information on both essential factors of the reaction (i.e. specific activities in commercial enzyme preparation and the cell wall structure of berry tissue). In this study, the different combinations of pure recombinant enzymes and the recently validated high throughput cell wall profiling tools were applied to extend our knowledge on the grape berry cell wall polymeric deconstruction during the winemaking following a combinatorial enzyme treatment design.

Evidence for terroir effect associated with botrytisation relatively to compounds implicated in typical aromas of noble rot sweet wines

Recent studies have demonstrated the role of certain lactones, particularly 2-nonen-4-olide, and volatile thiols (3-sulfanylhexan-1-ol) in the over ripped aromas of noble rot sweet wines (Stamatopoulos et al. 2014ab). These compounds are partly formed during the maturation and under the activity of B. cinerea on grapes. This research was carried out in the vineyard of Sauternes with aim to better understand their genesis depending on the grape over-ripening on two different soil types during 3 vintages. Thus, the study was conducted, with the Sémillon grape, during vintages 2012, 2014 & 2015, at 4 stages of over-maturation of the grapes (healthy, pourri plein, pourri roti, pourri roti + 15 days) considering two vineyard plots with different soil characteristics (calcosol & peyrosol) planted with the 315 Sémillon clone and grafted on 101-14 rootstock respectively in 1981 and 1980 and cultivated with the same vineyard management. Volatile lactones were assayed by liquid-liquid extraction followed by GC/MS analysis and the precursors of 3-sulfanylhexanol by an adaptation of the method by Capone et al. 2010 (SPE-
UPLC/FTMS).