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The Physics of Festive Fizz

Posted on December 18, 2014 By Tony

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.

Secondly, 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.

References

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

Posted on November 14, 2014 By Tony

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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

Increasing Alcohol Content in Red Rioja

Posted on October 6, 2014 By Tony

The Consejo Regulador (regulatory authority) for the vineyards and wines of Rioja was established in 1926. They carefully maintain and publish statistics of the Rioja Wine Industry, which allows a number of important parameters to be tracked through time.

In the 2013 vintage, the wineries within the Rioja DOCa produced 2.64 million hl of wine. As part of the Rioja wine approval process, there is a regulatory requirement for a sample from each tank of wine to be subjected to analytical (and sensory) investigation. Last year 3,973 wine samples were analysed by the Rioja Control Board, for parameters such as pH, volatile acidity and Alcohol content (abv). Although the raw data has not been published, the summary data provides a useful snapshot of the vintage, and provides the opportunity to compare with earlier vintages as far back as 2001.

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In the case of alcohol content for red wine there is, as would be expected with any agricultural product, a good deal of variation between vintages. Underlying this scatter is an upward trend which amounts to an increase of abv of ca. 0.5% from 2001-2013. (The p-value associated with the trend line is 0.03; values of less that 0.05 are generally considered significant). The causes of this increase (e.g. climate? picking dates?) are presently unclear, and there is currently no reason to believe that it will necessarily continue in future.

Six Reasons Why Wine Australia’s #InspiredTasting Was A Hit

Posted on September 13, 2014 By Tony

Wine Australia held a wine tasting event for Press and Trade in London last Friday (September 12th, 2014) entitled “Inspired Tasting“. Given the number of tastings that are being held in London this month, never mind this year, you could be forgiven for thinking that this would not have been particularly remarkable. Yet amidst a crowded tasting calendar, this event shone brightly. Here’s why.

1. Australia’s Winemakers Have Upped Their Game

Changes that have been implemented in the Australian wine industry over the past 5-10 years are now becoming evident in bottle. In the vineyard, more widespread Precision Viticulture, attention to choice of clones, and better water management are some of the changes which have lead to improved fruit quality. Meanwhile, in the winery, changes have been made to fermentation temperatures with less racking and a reduction in the use of new oak barriques. The combination is producing some outstanding vibrant and complex wines which show more typicity of cultivar and place. Still on the wish list? More earlier picking for those of us who find a bottle of 14.5% abv heavy going over dinner.

2. Every Wine Has A Tale To Tell

The Inspired Tasting event was first held in 2013, with the twist that each of the wines was chosen not by Wine Australia, but by a member of the Trade who had visited Australia. Not only that, but attached to each wine was a label with comments from the nominator as to why they had selected that particular wine. This approach, repeated this year, serves to present wine in its totality, with many nominators speaking not so much of the tannins and acidity but rather of the the sun, the food, and the people that they encountered at the winery. Whatever wine educators may say, wine isn’t just about its composition. The stories behind the wine are all important.

3. There Were Only A Hundred Wines

Wine tasting is hard work. Swirl, sniff, sip, repeat. Oh, and try to think about the wine, how it compares to others, make a judgement and record some legible, meaningful, notes. Spend, say, 3 minutes on a wine (not terribly long as any Diploma student will tell you) and 100 wines is already 5 hours of steady work. So big tastings can be a nightmare. The Beautiful South Tasting at Olympia had many, many, good points this year, but the sheer number of wines on show was overwhelming for many attendees.

4. Top Rate Masterclasses

Masterclasses are a great opportunity for promotional organisations to educate consumers about aspects of their wines. Yet all too often it’s an opportunity lost. Too frequently we hear something like, “the vines are grown on limestone soil, which is why the wines have retained such crisp acidity”, or similar nonsense. Fortunately, Justin Knock, really knows about Australian wine, the changes taking place in the industry, and has the ability to put across his knowledge in a clear, no-nonsense, manner. Other promotional organisations, please take note!

5. Location, Location

Australia House is centrally located and, for many people, an easier venue to reach than, say, the ExCeL Centre or even Olympia. It’s a building with a grand interior, and also spacious relative to the number of attendees. At the tasting there was room to breathe and not to be constantly jostled by others. The Masterclasses were held in a separate room which was quiet, spacious and with plenty of natural light. How fortunate are Wine Australia to have such facilities at their disposal.

6. Use Of Social Media

Social media isn’t for everyone, but many wine experts and consumers have found Twitter to be a particularly convenient way to share thoughts, recommendations, facts and ideas. The hastag #InspiredTasting used for this event was clearly publicised and gave anyone interested an opportunity to share their thoughts while the tasting was still taking place. And @Wine_Australia was interacting with the posted comments. Hardly rocket science for 2014, but another attention to detail that helped make the event such a success.

French Wine Industry: A Strategic Plan to 2025 From FranceAgriMer

Posted on July 16, 2014 By Tony

Who looks after the overall wellbeing of the French wine industry? The Interprofessions, INAO, DGDDI, and French Ministry of Agriculture, amongst others, are all involved in the collection of wine-related data. So there’s plenty of information available, but not always a great deal of in-depth analysis, at least not on a country-wide level.

Recently, FranceAgriMer took on the task of examining the current state of the French wine industry and coming up with a strategic plan suitable for carrying the industry forward through to 2025. That’s a highly ambitious undertaking set within the overarching themes of: (1) Maintaining a sustainable National market; and (2) Increasing the value and volume in export markets.

The report opens with key figures about the current state of the French wine industry and acknowledges its weaknesses in a SWOT analysis. These include: Erosion of export market share; Economic difficulties in some vineyards; Declining domestic consumption; High costs and low productivity compared to some competitors; and a regulatory framework which discourages innovation.

Following the scene setting SWOT analysis, the report follows the lines of a clasical management report with seven key thematic questions; five levers for addressing the two overarching themes; and 73 measures proposed to achieve 21 objectives … The objectives range from improving economic analysis to managing climatic risk; from encouraging innovation in the French wine industry to improving the health of French vineyards. This is all good stuff, though most of it is (hopefully) also being considered by other generic wine organisations representing competitor countries.

So the details of implementation are really important and here the report feels threadbare. Few would argue against more co-operation between Inter-professionals – but how exactly is this to be achieved? And measures designed to manage climatic risk are surely to be welcomed – but is proposing that adequate insurance cover be available a sufficient response?

Make up your own mind by reading the full report which is available to download here (PDF)

Classification of English Sparkling Wine, 2014

Posted on June 30, 2014 By Tony

English sparkling wine has been on a roll for a few years now. After all it was back in 2010 that Nyetimber’s Classic Cuvée 2003 was judged the world’s best sparkling wine at Bollicine del Mondo; the same year that Ridgeview won Decanter’s International sparkling wine trophy with their Grosvenor Blanc de Blancs 2006. Since then the vineyard area in England has reached an all time high, driven largely by new plantings of Chardonnay and Pinot Noir with sparkling wine in mind. So perhaps it’s time to ask, who are the best producers of English sparkling wine?

There are already many competitions which attempt to assess the quality of individual English sparkling wines, including the Decanter WWA, the International Wine and Spirit Competition, the International Wine Challenge, the UK Vineyards Association Competition and the Judgment of Parson’s Green. These will be joined later this year by the Champagne & Sparkling Wine World Championships. There’s certainly no shortage of competitions out there which English sparkling wines can (and do) enter and also a great number of medal-winning English sparkling wines.

One approach to determining the best producers is to pool the results from the various competitions and to see who’s won the most awards. Unfortunately it’s not quite so simple for a couple of reasons. Firstly, when assessing producers (as opposed to individual wines) you want to see how they have performed over a period of time. Yet many English sparkling wine producers were established quite recently and may have only entered competition this year. Producers such as Langham and Sugrue Pierre have produced some outstanding individual wines, but do not yet have a substantive track record.

Secondly, producers often don’t enter the same wine into every competition, indeed they often don’t appear to enter a particular competition at all. (I say “appear” because competition organisers are notoriously protective about providing information on wines which fail to win awards.)

Thirdly, judgments have to be made as to what medal tallies actually mean. Some producers may enter five or more wines into a given competition, whereas other producers might have restricted themselves to a single entry. Different competitions appear to award a significantly higher proportion of gold medals to wines entered. So should a gold medal from competition x have equal worth to a gold medal from competition y? And how does a producer with say three silver medals compare with another producer who has a single gold? None of these questions have simple answers, so involve matters of judgment rather than spreadsheet calculations.

The final results shown below are based on compilations from the five competitions listed above for the period 2010-2014. Producers with track records for only part of this period are disadvantaged and have not been pro-rated in some way. In this sense the classification resembles the approach taken by Matthew Jukes and Tyson Stelzer in their Classification of New Zealand Pinot Noir. Presenting the results for English sparkling wine in terms of three classes seems appropriate given the current size and development of the industry. All the producers listed in the classification have produced noteworthy wines and there are many other producers not shown on this classification who are undoubtedly striving to enhance the quality of their products. This is a very exciting time both for producers and consumers of English sparkling wine.