The perfect bubble: foam formation in sparkling wine

The perfect bubble

Foam formation in sparkling wine

By Francois Botton¹, Alana Seabrook², Dr Clara Cilindre³, Prof Gérard LigerBelair³ and Dr Virginie Moine⁴

Introduction

Perfect foam and bubble formation in sparkling wine has been a topic of interest in Champagne and many other regions around the world for many years. Back in the early ‘90s the team of Prof. Maujean from Reims University developed the first device able to size and compare the quality of the foam from different wines (Mosalux, Brissonet and Maujean, 1991). In Bordeaux at the same period Prof. Dubourdieu and his team were focusing on the science of ageing on lees (Chatonnet and Dubourdieu,1992; Lavigne and Dubourdieu, 1994; Lavigne and Dubourdieu, 1996; Moine-Ledoux and Dubourdieu, 1996; Lavigne and Dubourdieu, 1999; Humbert and Moine, 2003). Nowadays, this work and knowledge, in conjunction with a key collaboration with Prof. Liger Belair and Dr Clara Cilindre whereby the focus is on the physics of the bubble, has led to a much greater understanding of how we can influence effervescence and foam in sparkling wine. Techniques include traditional, charmat, carbonation, transfer method and aging on lees for limited tirage time.

What does the perfect bubble look like?

In terms of the aesthetics of effervescence in wine, the “pinnacle” for tasters is to observe fine, elegant, and persistent bubbles in the glass regularly supplying a generous and stable collar to form a harmonious foam. Foam formation in this article refers to the size of the bubble, the amount of bubbles, the height and persistence of the mousse and ‘collerette’ (collerette refers to the ring of bubbles formed in a flute which remains after the wine is poured). In Champagne, there is a perception that smaller bubbles are preferred and are able to last overtime whilst larger bubbles may be perceived as ‘flabby’ and less than ideal (Union des Maisons de

Figure 1. Mechanism and interactions in the bubble-forming process

1 Global sparkling manager for Laffort 2 Laffort Australia/Winechek laboratories 3 Equipe Effervescence, GSMA, Université de Reims Champagne-Ardenne, France 4 Research director at Biolaffort

Champagne, 2021). Cilindre et al., (2021) observed fermentation temperature of the prise de mousse to bubble size and found that lower temperatures presented smaller bubbles (with P < 0.05) in the foam collar throughout the wine tasting, however there are many other factors which can contribute to bubble size.

Theoretically one can estimate that a single bottle of sparkling wine using traditional method with 24 g/l of sugar added for the secondary fermentation will contain nearly 12g/l of carbon dioxide. When opening the bottle and serving in the glass, approximately 80% of the initial carbon dioxide concentration is released via evaporation. Only 20 per cent can form bubbles (Liger-Belair, G., 2014). This leaves around one million bubbles involved in the formation of mousse and collerette in a 100ml glass of sparkling. Nucleation sites in the glass are critical to the birth and formation of bubbles. Among them we can find microfibers or roughness and imperfection present on the surface of the glass which are able to act as nucleation sites (Liger-Belair et al. 2008). It is therefore very difficult in real conditions to compare side by side two glass and judge the quality of the effervescence. In our study, we are using laser punch glassed designed by the glass maker to ease the nucleation of bubbles that we combine with a strict cleaning procedure to avoid random nucleation sites: with the same number of nucleation sites in each glass, it is possible to compare the aesthetic of effervescence in two different samples. Also, a precise monitoring of CO₂ concentration in each sample we want to compare is crucial. Indeed, the abundance of bubbles and the kinetic of bubble formation is directly linked to this parameter. There are many aspects to the winemaking process which can impact foam formation in sparkling wines. Sparkling wines contain greater or lesser quantities of surfactant macromolecules from grapes and yeasts (Figure 1). They play a fundamental role in the lifespan and quality of the bubbles in a glass. From its birth, the bubble is charged with CO₂, its growth is directly linked to the concentration of dissolved CO₂ in the wine. Then it detaches from its nucleation site and rises to the surface. During its journey, it captures the surfactant molecules in the wine, including mannoproteins. When the bubbles reach the wine’s surface, the surfactant macromolecules play their protective role by prolonging their lifespan and thus promoting the formation of the collar.

Figure 2. Diameter of bubbles in the collerette, at one and 10 minutes after the end of pouring (12

months) with the control (aged on lees); EL means an addition of yeast extract; MP1 and MP2 are distinct mannoprotein fractions which were found to directly impact foam height, persistence of

collerette and bubble diameter.

Factors affecting foam formation Protein stabilisation and use of bentonite

Many factors effect foam formation in sparkling wines but it is often the use of bentonite which is the most critical. Foam active compounds which create tension around the bubble are linked to the protein content and extended aging on lees. The heat unstable proteins present in white wines can create a haze in wines. In standard white wine production these are often removed via the use of negatively charged bentonite. Bentonite is unselective and will remove both heat unstable and heat stable proteins and as a consequence has a direct negative impact on foam formation (Marchal et al., 2002; Maujean et al., 1990).

Pallatised storage with CellaStac

Other factors

Grape maturity can have a direct impact on foam formation. Liu et al. (2018) found the increasing level of maturity indicated higher levels of glycoproteins which corresponded to a higher mousse height. Whilst picking early may avoid the incidence of Botrytis cinerea, it was found to have lower levels of glycoproteins directly correlated with foam height (Marchal et al., 2001, 2006, 2017; and Cilindre et al., 2007, 2008). Factors including the press fraction and the amount of carbon used to decolourise have all been found to impact the mousse height. Lipids from the waxy layer of the grape have anti-foaming properties and the use of carbon removes foam active proteins (Marchal et al., 2002; Maujean et al.,1990). The type of filtration used can also impact the foam height by removing or retaining colloids that can prevent foam formation (Robillard et al. 1993; Kemp et al. 2005). Ethanol content is also a key factor in foam formation, lower alcohol levels have a positive impact on the bubble tension and foam height (Maujean et al., 1990). Prosecco wines have lower ethanol levels around 11% v/v and often have excellent mousse properties; whereas Champagne has average value of 12.5% v/v alcohol (Dussaud et al., 1994) and optimise their mousse formation and duration thanks to their extended aging on lees.

Role of mannoproteins in bubble aesthetics

The research program on the aesthetics of effervescence, launched by BIOLAFFORT® in 2014 in collaboration with Prof. Gérard Liger Belair’s team at the University of Reims Champagne Ardennes, allowed us to study the effect of the different mannoprotein fractions of yeast, then to demonstrate their impact on the quality and stability of the wine foam. Trials presented here were carried out on a rosé crémant from Bordeaux after 12 months of aging on lees. The base wine was heat stabilized with 80g/ hl of bentonite MICROCOL®Alpha and a different selection of mannoporoteins were added at tirage with yeast extract (EL), mannoprotein fraction 1 (MP1), mannoprotein fraction 2 (MP2) and a combination of MP1 and MP2. The different fractions of mannoproteins have very different molecular weights and properties. The foam height and persistence of the bubbles was improved on all treatments (Figure 2 and 3). After both one minute and 10 minutes the collar thickness was lower for the control than any of the other treatments (Figure 4a). The diameter

Figure 3. Diameter of the bubbles in the collerette , at one and 10 minutes after the end of pouring (12 months) of the bubble was greatly impacted by the mannoprotein in question and a combination of both led to the best combination of optimal bubble diameter (approximately 0.5mm) and foam height (Figure 4a and 4b). MANNOSPARK® is a specific formulation resulting from this study, for improvement in the size of the bubbles, and the thickness and stability of the collar, in order to obtain a harmonious and persistent foam in sparkling wines. This can be added to all sparkling wines including those made with charmat, transfer, carbonation at any stage of the process to improve the size of the bubble, persistence of the collerette and height of the mousse without impacting the ability of the wine to go through a filter. The data from this article was sourced from work conducted by the Molecular and Atmospheric Spectrometry Group (GSMA), a joint research unit between CNRS and the University of Reims Champagne-Ardenne (URCA). Bubble Physics Laboratory, Prof. Gérard LigerBelair published on OEno-IVAS 2019, Bordeaux.

References

Brissonnet F, Maujean A. Identification of some foam-active compounds in champagne base wines. American Journal of Enology and Viticulture. 1991 Jan 1;42(2):97-102. Cilindre C, Henrion C, Coquard L, Poty B, Barbier JE, Robillard B, Liger-Belair G. Does the Temperature of the prise de mousse Affect the Effervescence and the Foam of Sparkling Wines? Molecules. 2021 Jan;26(15):4434 Liger-Belair G, Cilindre C. Recent Progress in the Analytical Chemistry of Champagne and Sparkling Wines. Annual Review of Analytical Chemistry. 2021 May 20;14. Liger-Belair G. How many bubbles in your glass of bubbly? The Journal of Physical Chemistry B. 2014 Mar 20;118(11):3156-63. Chatonnet and Dubourdieu,1992. Mitigation of wood impact on smell and taste [Atténuation de l’impact olfactif et gustatif du bois] Lavigne and Dubourdieu, 1994. Protection of color against oxidative phenomena [Protection de la couleur contre les phénomènes oxydatifs] Lavigne and Dubourdieu, 1996. Light mercaptans fixation by lees [Fixation par les lies des mercaptans légers] Moine-Ledoux and Dubourdieu, 1996. Improvement of protein and tartaric stability [Amélioration de la stabilité protéique et tartrique] Lavigne and Dubourdieu, 1999. Aging potential [Aptitude au vieillissement] Humbert and Moine, 2003. Taste improvement [Amélioration gustative] Marchal A, Marullo P, Moine V, Dubourdieu D. Influence of yeast macromolecules on sweetness in dry wines: role of the Saccharomyces cerevisiae protein Hsp12. Journal of Agricultural and Food Chemistry. 2011 Mar 9;59(5):2004-10. Pin-He Liu, Céline Vrigneau, Thomas Salmon, Duc An Hoang, Jean Claude Boulet, et al.. Influence of Grape Berry Maturity on Juice and Base Wine Composition and Foaming Properties of Sparkling Wines from the Champagne Region. Molecules, MDPI, 2018, 23 (6), 21 p. ff10.3390/molecules23061372ff. ffhal01918063f Vanrell, G.; Canals, R.; Esteruelas, M.; Fort, F.; Canals, J.M.; Zamora, F. Influence of the use of bentonite as a riddling agent on foam quality and protein fraction of sparkling wines (Cava). Food Chem. 2007, 104, 148– 155 Robillard, B.; Delpuech, E.; Viaux, L.; Malvy, J.; Vignes-Adler, M.; Duteurtre, B. Improvements for sparkling base wine foam measurements and effect of wine filtration on foam behaviour. Am. J. Enol. Vitic. 1993, 44 (4), 387−393 Kemp B, Alexandre H, Robillard B, Marchal R. Effect of production phase on bottle-fermented sparkling wine quality. Journal of Agricultural and Food Chemistry. 2015 Jan 14;63(1):1938. Union des Maisons de Champagne. 2021. https://maisonschampagne.com/en/appellation/stages-inwinemaking/fromstill-wine-to-spar

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