Sparkling wines contain carbon dioxide in order to create fizz and bubble, and are usually made from the Pinot Noir, Chardonnay and Pinot Munier grape varieties. Arguably, the most famous sparkling wine has to be Champagne which is produced following strict guidelines for planting, cultivating, harvesting and in production. However, generally speaking, all sparkling wines are difficult and time-consuming to make as a great deal of patience is required in order to ensure that the blend will deliver the desired taste. The grapes used to produce sparkling wines are harvested earlier than those of most other wines. This ensures that the natural sugar levels remain as low as possible, which in turn, also restricts alcohol content – sugars are reintroduced at a later stage. Initial fermentation is strictly controlled, after three weeks the wine is tested to ensure that all the natural sugars have been converted to alcohol. Due to the grapes having been pressed rather than crushed to avoid oxidisation and over-colouring, sediment and particles collect in the bottom of bottles during fermentation. Therefore, at this stage the sediment is separated and the wine is re-bottled in to fortified bottles as this is when bottles and casks can burst open due to the intense pressure that has built up. Throughout fermentation, sediment is periodically removed from the neck of the bottle where it has collected – a process called “disgorging.” At the end of fermentation, it is topped off with a small amount of sweetened wine, and a new cork is added.
However, there is also another process that can be used in sparkling wine production, called the transfer process. In this process, the wine is filtered directly from the tanks it is stored in and then placed in bottles under-pressure. This drastically cuts production time because there is no disgorging or riddling required (riddling is where bottles of sparkling wine are periodically turned).