Preservation of sparkling wines & Champagnes

IF YOU ARE SHOPPING FOR WINE PRESERVATION YOU NEED TO READ THE FACTS BEHIND THE FICTION

Those clever boffins in white coats in Reims, the home of Champagne, were recently able to confirm that ‘there are 30 times more flavour-enhancing chemicals in the bubbles than in the rest of the wine’. This has completely changed the industries understanding of the role of bubbles and goes some way to explaining why the traditional Champagne method of production tastes so much better.

Whilst the industry has been shocked to learn just how significant a role bubbles play in conveying the essential flavours of the wine, the debate has inevitably swung to address the best ways to protect open bottles of Champagne and sparkling wines from bubble loss.

As a W.S.E.T qualified wine educator, wine by the glass consultant and still wine and Champagne preservation expert for more than 16 years, I have seen all sorts of gimmicky gadgets with extravagant unproven claims. Glossy brochures and websites come and go as operators realise that preservation techniques based on myth and ‘bad science’ simply don’t work.

HOW DOES CHAMPAGNE GET ITS BUBBLES

Before we look at how and why Champagne goes flat, lets look at how it gets its bubbles in the first place. Remember, the finer and more plentiful the bubbles the more of the taste and flavour of the Champagne will be conveyed to the drinker.

Champagne producers firstly create a still wine blend (or cuvee) using one or more of the three famous grape varieties - Chardonnay, Pinot Noir and Pinot Meunier. Next, sugar and yeast are added to the cuvée and the wine is bottled. During the secondary fermentation process that follows yeast converts the sugar to alcohol (the ‘kick’) and carbon dioxide (CO2) bubbles (the ‘pop’). The CO2 is gradually dissolved and trapped inside the Champagne bottle. Once the lees (discarded yeast waste and other residue) are removed from the bottle it is then essential that the bottle remains completely airtight or the famous ‘sparkle’ will be lost.

WHY DOES AN OPENED BOTTLE OF CHAMPAGNE GO FLAT

As with all wines one of the biggest threats to an opened bottle of Champagne comes from the air – or more particularly from the oxygen (O2) contained within it. Champagne however is also at immediate risk from the loss of the pressure retaining device (the cork!), that has kept the sparkle in situ since the drink was produced. The threat of oxidation from atmospheric oxygen is compounded by the swift and continuous loss of carbon dioxide from the opened bottle – a process that can turn a ‘sparkling occasion’ into a damp squib within a matter of hours.

The carbon dioxide pressure in an unopened Champagne bottle can reach more than 140 pounds per square inch, that’s about twice the pressure used to inflate a double-decker bus tyre – and the reason that Champagne bottles are so strong and heavy! As soon as the cork is removed carbon dioxide ‘floods’ out of the opened bottle – give it a shake first and the liquid comes with it!! Carbon dioxide loss continues until the gas pressures inside and outside the bottle are equalized, or until an effective preservation technique halts the loss of gas.

Once the flow of carbon dioxide has slowed significantly (because of pressure equilibrium or preservation), the process of oxidation takes over as the major threat to the Champagne. From a combination of the second law of thermodynamics and the laws of partial pressures of gases, it is possible to accurately estimate the rate of oxidation of the Champagne remaining within a pert consumed bottle – influenced by temperature, alcohol content and the volume of available oxygen, the whole exercise becomes rather academic if the Champagne has already lost its sparkle.

GADGET OR EFFECTIVE PRESERVATION?

There are far too many wild and whacky preservation gadgets on the market to cover comprehensively, so here’s the inside story on a few.

The Silver Spoon – The preferred preservation technique of every Grandmother who was lucky enough to drink Champagne, this really is an ‘old wives tale’. Successful preservation has to slow, or ideally halt, the loss of carbon dioxide from the Champagne and it’s hard for all but the most liberal minded to see how a spoon could ‘seal’ an opened bottle. (CO2 is comparatively inert and does not react with Ag (silver), so there’s not even the possibility of claiming preservation via some obscure chemical reaction) On the ‘oxidation’ front, the spoon does nothing to extract air from the bottle (eliminating oxygen/Champagne contact) and does nothing to prevent more air from continually entering the bottle.

RESULT –LOVELY IDEA, BUT REGRETTABLY A GADGET


The Champagne Stopper – In best case these stoppers create an air tight seal stopping carbon dioxide leaving a part consumed Champagne bottle. Unfortunately the oxygen that is trapped in the bottle when the stopper is applied will remain in direct contact with the Champagne, and oxidize it at a calculable rate. The major flaw with this technique is that the Champagne remaining in the bottle will continue to release carbon dioxide (it’s ‘sparkle’), until a ‘pressure equilibrium’ is created within the bottle. If the bottle contains a large volume of liquid, then the pressure equilibrium may be achieved with only minor bubble loss from the Champagne. As the volume of liquid in the bottle decreases, so a smaller and smaller amount of liquid has to emit a larger and larger volume of carbon dioxide before the pressure equilibrium is reached.

A bit ‘tecky’, but what it means in essence is that Champagne stoppers can be quite effective for short term preservation provided there’s plenty of Champagne left in the bottle and the liquid hasn’t been allowed to lose its natural CO2 through being left open too long before resealing. As a general rule, anywhere from two thirds of a bottle down and this technique becomes less and less reliable (the number of times a bottle is opened is also significant – the more often, the worse the technique)

RESULT –OK SOMETIMES, BUT MOST OFTEN NOT – A HIT AND MISS GADGET


Hand operated and battery pumps – These gadgets claim that the introduction of air under pressure will prevent oxidation and bubble loss in opened bottles of Champagne! Bizarre!

The logic seems to run that air (or rather all its constituent gases) can be used to ‘lock’ carbon dioxide in solution. It can’t, it won’t and it doesn’t! Actually what happens is that as the pressure of air in the bottle is increased, the solubility of each gas within the air increases – the result is that oxygen within the air will be even more quickly absorbed into the Champagne, actually accelerating the oxidation of the drink.

Tecky again but it’s a fact (For those with a morbid fascination of these things, Google ‘Henry’s Law’ and check out the science of gas solubility for yourself - Henry’s Law also states that solubility is significantly increased in liquids at low temperatures such as the serving and storing temperature of Champagne.)

It’s also worth remembering that these gadgets don’t have ‘filters’ to scrub the air that’s being forced, under pressure, into the Champagne bottle. Airborne contaminants are the source of most of the world’s pollution and disease transmission – don’t know about you, but I don’t much fancy it being forced into my Champagne!

RESULT – BASED ON BAD SCIENCE – A REAL ‘GADGET’


Le Verre de Vin – Operates by introducing a precisely controlled head pressure of CO2 into the void in a Champagne bottle. The result is a perfect pressure equilibrium that ‘locks in’ the natural sparkle in the Champagne, irrespective of the amount remaining in the bottle. It sounds very simple and for the operator it is, however the science behind the re-sealing process is firmly grounded in proven, traceable facts.

CO2 is the only gas that can be used in the Le Verre de Vin’s super-atmospheric re-sealing process, since, quite logically, it is the only gas with the same molecular structure as the CO2 in the Champagne itself. The ‘structure’ is important, since gases don’t behave like liquids or solids – the only effective way to create the pressure balance so important in the preservation technique, is with identical gases.

Applying ‘exactly’ the right pressure of CO2 means that the natural fizz in the Champagne is ‘locked’ in place – and Le Verre de Vin achieves the optimum reseal pressure on each and every use with 99%+ accuracy. So why is control of the gas pressure so vitally important?

• Apply too little pressure and the Champagne will continue to lose those all-important bubbles until a pressure equilibrium is achieved within the bottle – which could be at the expense of the Champagne losing its sparkle.

• Apply too much pressure and the Champagne will absorb the excess gas. Outwardly this might not appear to be too bad a thing – in reality however the structure of the mousse (bubbles) within the Champagne is likely to change, and the fine streams of delicate, flavour laden bubbles will be replaced by large, erratic, lemonade style bubbles! Not exactly ideal in a fantastic glass of Champagne!

The science behind this deceptively simple to use wine preservation system is clear for anyone to see and understand, and has resulted in Le Verre de Vin being awarded worldwide patents and achieving international recognition as ‘The Industry Standard for preservation’.

RESULT – PERFECT PRESERVATION


Well there you have it, the inside story on what’s hot and what’s not! The wise old sayings of ‘Caveat Emptor’ and ‘If it sounds too good to be true…then it probably is’ have never been more valid than in the still wine and Champagne preservation market today.