The Winemaker’s Think Tank: Vol 1- Why is My Wine Fizzy?


Wine expert testing wine silhouette image


The Winemaker’s Think Tank? 

Every Thursday we will post about a few frequently asked questions that our winemaker has answered. If you have a winemaking question you would like to have answered, please email us at support@juicegrape.com and we will try to get into next week’s post. Cheers! 🙂


Why is my wine fizzy?

Wine may be fizzy for one of two reasons: trapped gas within the wine leftover from fermentation, or a re-fermenting wine. Yeast exudes two substances upon fermentation: alcohol and carbon dioxide. Often times, carbon dioxide is exuded in such small bubbles that the weight of the liquid wine is too heavy to allow the gas to escape. This gas can easily be discharged through a process called degassing. Degassing involves the extreme agitation of the wine via stirring or pumping over. If you own a pump, you can set up the hoses in a circuit, and pump over vigorously to allow the gas to escape. You can also buy a degassing stirring wand that attaches to a cordless power drill. Simply attach it to the drill, place in the wine, and stir. The agitation will allow any trapped bubbles to rise to the surface and dissipate.

The wine may also be fizzy due to a re-fermentation. Even after racking, there may still be suspended yeast cells within the wine. The addition of potassium metabisulfite is necessary to ensure the killing off of remaining yeast cells, especially if the wine has any residual sugar or if the winemaker has plans to back sweeten the wine. Potassium sorbate is also strongly recommended if the winemaker intends upon back sweetening a white wine. The potassium sorbate will encapsulate the yeast cells, rendering them sterile and unable to ferment any sugar that is then added to the wine. (Note: Potassium sorbate cannot be used on any wine that has gone through Malolactic fermentation.) If the winemaker would prefer physical rather than chemical sterilization, a sterile grade (.45micron) filter may be used to physically remove any yeast or bacterial cells and prevent any further fermenting from occurring in the bottle.

*Please Note:

  • Brettanomyces is carbon dioxide as well.
  • The issue of filtration raises a host of issues.  Sterile in winemaking is not achieved unless using an absolute filter (cartridge filter at the 0.45 or lower) and not a nominal filter (plate or pad filter  such as the Grifo or SuperJets).  The cartridges for the Enolomatic filter set-up are not rated as sterile either.

We hope this information helps with your winemaking. If you have any follow up questions or winemaking questions in general, please email us at support@juicegrape.com.