Sparkling wine: The tank / Charmat method
Italian made Prosecco is the worlds best selling sparkling wine, selling more bottles that Champagne and Spanish Cava combined. Made primarily from the Glera grape (it must be 85% Glera), Prosecco generally has a lighter fruit forward style which is light and refreshing. No wonder it is so popular!
Prosecco differs from Champagne and Cava not only in the grape varieties used to produce it, but also in the method used to create the bubbles. This is know as the tank method / Charmat method. And of course, this method is not limited to Prosecco. A number of frizzante wines around the world are made this way. But how does it work? In this post that is exactly what we are going to explore.
A base wine similar to the traditional method
In a previous post we explored the traditional method and the creation of a slightly acidic base wine, from grapes picked before fully ripening. A similar process is used during the making of a tank method wine. In Prosecco, the majority of grapes are going to be Glera, which is a thin skinned and quite delicate grape. Care has to be taken when harvesting and pressing. It is also quite late ripening, so it is usually picked around September time. The grapes will be sorted carefully once harvested and any MOG (matter other than grapes) removed.
Once grapes are cleaned and sorted, a gentle pressing takes place. Then the free run juice is taken for a clarification and filtering process to create a clear juice. For most tank method wines, this is going to be done in a temperature controlled way in stainless steel tanks. This helps preserve the fruit characteristics of the grapes. As with traditional method wines, a primary fermentation is started and completed in the tank by adding yeast. After the first fermentation different varieties may be blended together to form the base wine.
A different type of Secondary Fermentation
At this point in a traditional method production, the wine would be put into its bottles and secondary fermentation would occur there. A tank method wine does not undergo secondary fermentation in the bottle, but as the name suggests in a tank. A tirage liquid is added to the tank which combines yeast, nutrients and sugar which encourages a second fermentation to occur. This will cause some alcohol to be created, but most importantly carbon dioxide to be produced. This then dissolves in the wine causing it to become fizzy. The tanks are of course sealed to ensure the CO2 cannot escape.
A no frills ending
While traditional method wines are left to age on the lees in the bottle, the style dictates that it is fresher. Therefore it is less desirable to add those bready, brioche, biscuity notes. At this stage then, the liquid is bottled. There is no need for dosage, or disgorging as no sediment will be present. The wine can be bottled, corked and sealed ready for distribution. Prosecco is usually bottled between March and April where cooler temperatures help preserve the freshness. And from there is ends up being distributed for consumption.
So by comparison with the traditional method, the Charmat method is much quicker, and therefore much less expensive. This is why you can buy a bottle of Prosecco for much less than you can buy a bottle of Champagne. Although, often Cava does not attract the same high price point. Prosecco is, in many ways then, a marketing triumph. It has become the drink of choice for a lot of people and it is being consumed in very high volumes. And what’s not to like – light, bubbly, fruit forward and refreshing – a perfect summer drink (well and spring, autumn and winter!).
So next time someone hands you a glass of Prosecco, you’ll know the difference between that and a traditional method sparkling wine. And of course there is a whole world of other tank method wines out there to discover – so what are you waiting for? In the meantime, keep exploring this beautiful planet we live on, one glass at a time!