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The Physics of Festive Fizz

With the holidays fast approaching, many of us are looking forward to drinking a glass or two of Champagne and other sparkling wines.  After all, these are perfect celebratory drinks – but what does physics have to say about how they might best be served?

1. Gently Pour into an Inclined Glass

The traditional way of pouring Champagne and sparkling wines is into an upright glass, which produces a frothy head. Sommeliers may love the drama that this produces, but a great deal of CO2 is lost in the process. This is bad news because such a dramatic loss of dissolved CO2 will (1) result in a glass which is less vivacious and (2) contain lesser amounts of volatile organic compounds (VOCs) which are carried in bubbles.


Research by Gérard Liger-Belair and colleagues at the Université de Reims has shown that by pouring into an inclined glass – much as one would pour a beer – the wine can contain up to twice as much dissolved CO2.  And that means a longer-lasting bubble stream and more intense aromas.

2. Use Flutes Not Coupes

Coupes are the traditional glass of choice for serving Champagne and sparkling wine, but they are to be avoided, even those that are modelled on Kate Moss’s left breast.  There are two main reasons for this.  In a coupe, the sparkling wine will have a much greater surface area in contact with the air, compared to a flute.  Since much CO2 is lost by diffusion at this interface the flute will naturally retain CO2 for longer.

Champagne-VortexSecondly, the differing shape of coupes and flutes result in differing patterns of convection and surface bubble burst.  These bubbles are not merely aesthetic but carry with them volatile organic compounds which are a characteristic of that particular sparkling wine. With a flute the vortex zone covers the entire width of the glass and VOCs are contained within a relatively small volume. By contrast with a coupe, the vortex zone covers only about half of the wine surface.  This results in a doughnut shape adjacent to the rim with far fewer bubbles and VOCs.

3. Serve Chilled but not Cold

The temperature of sparkling wine affects its viscosity and the rate at which CO2 molecules are able to diffuse.  This means that the cooler the sparkling wine the longer it will retain its dissolved CO2.  Just as a rapid loss producing a frothy head is undesireable, so also is too slow a loss.  The latter with a sparse flow of bubbles, is aesthetically less apealing and also has a reduced flow of VOCs.  Experience of tasters suggests that 8°-10°C is a good temperature at which to serve the majority of Champages and sparkling wines.



Beaumont, F et al. (2013) Temperature Dependence of Ascending Bubble-Driven Flow Patterns Found in Champagne Glasses as Determined Through Numerical Modelling.  Advances in Mechanical Engineering, 10pp

Liger-Belair, G. (2013) Uncorked: The Science of Champagne. 216 pp

Liger-Belair, G. et al. (2010) On the Losses of Dissolved CO2 during Champagne Serving. J. Agric. Food Chem. v 58, p. 8768–8775

Liger-Belair, G et al. (2012) Monitoring Gaseous CO2 and Ethanol above Champagne Glasses: Flute versus Coupe, and the Role of Temperature. PLoS one

The Beaujolais Wine Region in Figures

Beaujolais is one of the world’s most famous wine regions. Best known today for Beaujolais Nouveau, the region has been in crisis since 2000 as low prices, coupled with dropping demand, have forced many wine farmers out of business.  With the region seeking to reinvent itself, this 7 page free downloadable PDF, Beaujolais in Figures summarizes the readily available data to help explain the Beaujolais story.

Winestats would like to thank the staff of Inter Beaujolais for providing data used in this study

Five Things Worth Knowing About the Texas Wine Industry

Texas wine is not very well known outside of the Lone Star State and there is precious little awareness of it outside of the US.  This may be about to change as increased investment, the entry of new entrepreneurs and more suitable cultivars are moving the industry forward.  So with exciting times ahead, here are five things worth knowing now about the Texas Wine Industry.

1.  The Number of Texas Wineries is Increasing Rapidly

Texas-Wineries According to the Texas Wine & Grape Growers Association, in January 2013 there were 273 registered wineries in Texas.  Ten years previously there were only 54. Expansion of the number of Texas wineries has really taken off since the beginning of the 21st century.

2. Texas Grape Production Has Not Increased This Century

Texas-Grapes-UtilizedLimited vineyard planting (see below), Pierce’s Disease and unfavourable climatic conditions (2011 drought; 2012 Spring freeze) have together created a situation in which Texas grape production has been not expanded in line with demand. For some years now there has been a shortage of Texas grapes.

3. More Texas Vineyard is About to Come Into Production

Texas-Vineyard-AreaThe recently released 2012 USDA Agricultural Census of Texas has shown a large increase in the amount non-bearing vineyard, reflecting a significant amount of new vineyard planting since 2010. These non-bearing vineyards should be bearing in 2014 or 2015, which will roughly double the amount of bearing vineyard and hence grape production capacity.  With additional vineyards still being planted, it shouldn’t be too long before the Texas vineyard exceeds 10,000 acres.

4. With Limited Texan Grapes, Winemakers Are Using Californian Grapes

While some Texan wineries are able to source sufficient Texan grapes for their needs, most cannot.  Aided by a laissez-faire attitude towards labelling, winemakers are currently able to describe their product as “Texan wine” providing a minimum of 25% of the juice is from Texan grapes (Mariani, 2013).  That leaves an awful lot of leeway for using out of state grapes in Texas wine.  If you want to be certain that the wine in your glass originated with largely Texan grapes, then stick to those from one of the eight designated AVA regions of Texas.  A wine with an AVA designation guarantees that at least 85% of the wine’s grapes were grown within the AVA.

5. Texas is Still Discovering the Best Varietal Match to Terroir

Texas-Cultivar-Area-2010The modern Texas wine industry is arguably less than 50 years old, which isn’t a lot of time to determine which type of grapes grow best in which area.  The most recent USDA_NASS Texas Grape Survey showed that although Cabernet Sauvignon and Chardonnay were the two most planted grape cultivars, neither occupied more than 20% of the bearing vineyard.  A great variety of black and white cultivars are currently being grown, some in small amounts on experimental plots.  It will take several years, or perhaps decades, before the most appropriate mix of cultivars for Texas’ different terroirs is adequately determined.

Thanks to Natalia Velikova of The Texas Wine Marketing Research Institute for advising on available data sources


Do Decanter Wine Scores Correlate With Wine Price?

As wine consumers, we are often being urged by the trade to increase the amount of money we spend on a bottle of wine.  The argument, goes something like this.  Better wines require superior grapes, more careful vinification and perhaps longer ageing.  Since each of these factors incurs additional expenditure, better wines will inevitably be more expensive.  So if you want a better bottle of wine this holiday, well, simply open your wallet a little wider.

Score vs Price Plot for Soave (Sept, 2012)

Of course, such an analysis is way too simplistic as there are many factors which determine the price of a bottle of wine.  Larger producers may experience economies of scale and have larger marketing budgets.  Smaller producers may argue that they have a boutique offering with rareity value.  As consumers’ tastes change, retailers may have to scramble their prices so as to keep demand in balance with supply.

Similarly, it is very difficult – some would say impossible – to objectively assess wine quality. Not that this has stopped the majority of wine critics.  Although many of them will claim that it is important for consumers to read their tasting notes, most of them post-Parker feel obliged to attach a numerical rating. Retailers love scores as they move markets.  Consumers have been warned about the unreliability of wine scores, but nevertheless continue to make use of them in their buying decisions.


Score vs Price Plot for Albarino (Aug, 2012)

Score vs Price Plot for Brunello 2007 (Aug, 2012)












Given the complexity of factors which determine wine price and the difficulties of objectively scoring wines, we might expect there to be little relation between wine prices and scores.  So is this the case?

Decanter magazine, in their print edition, publish regular reviews of particular wines with quality assessments by respected wine experts.   Each expert includes their numerical assessment of quality for each individual wine, which the magazine averages and then assigns to a quality band.

Plots of average score against price for three wine types (Soave, Albarino and Brunello di Montalcino 2007) show that there is a very low correlation between average Decanter wine scores and price.  Indeed in the case of Soave the correlation is slightly negative.  Wine purchasing will remain a complex decision process.