Everything About Secondary Fermentation

Secondary fermentation is an integral part of the brewing process, helping improve flavors, clarity, and the overall quality of the final product. It’s a valuable technique for both homebrewers and professionals, refining beverages to achieve a more mature and sophisticated flavor profile.

By settling out remaining particulates and allowing for the integration of additional ingredients, secondary fermentation contributes to the development of more complex flavors and greater overall stability. Understanding and mastering this process is vital for brewers looking to elevate their craft and produce exceptional beverages.

What is Secondary Fermentation?

Secondary fermentation is an additional fermentation stage that occurs after the initial fermentation is complete. Brewers transfer the beverage to a secondary vessel for further conditioning. While the first round of fermentation focuses on converting sugars into alcohol and carbon dioxide, the second round helps enhance complex flavors and improve clarity by settling out remaining particulates.

Process of Secondary Fermentation

The process of secondary fermentation involves preparation, transfer, monitoring, and plenty of patience to achieve the desired effect.


As with the first round of fermentation, preparation is key to success with secondary fermentation. All equipment must be clean and sanitized to prevent contamination, which could spoil the batch.

Brewers need to cleanse and sanitize all equipment they’ll be using, including the secondary fermenter, airlock, and siphoning tube.

Transfer to Secondary Fermenter

Next, transfer the brew from the primary to the secondary fermenter. During this stage, it’s crucial to take steps to minimize oxygen exposure, which could affect the brew’s taste, aroma, and shelf stability. Brewers use a siphon to carefully transfer the beverage, reducing splashing that could introduce oxygen. After transferring, the fermenter is sealed with an airlock.

Monitoring and Duration

After transferring the beverage, it’s important to monitor progress and maintain optimal fermenting conditions. Ideally, the temperature should hover between 18-26°C (64.4-78.8°F), depending on the beverage.

The process may take anywhere from one week to several months, depending on the desired outcome. As time passes, watch for signs of active fermentation. Indicators of active fermentation include slight bubbling in the airlock and sediment formation at the bottom of the fermenter.

Once the beverage reaches the desired result, the last step is to remove the beverage from the fermenter for consumption or bottling.

Pros and Cons of Secondary Fermentation

Secondary fermentation offers several benefits and some drawbacks.


  • Enhanced flavor development: Second fermentation helps mature the flavors, minimizing off-flavors and creating a more refined product.
  • Carbonation control: This stage offers better control over carbonation levels, allowing brewers to achieve the ideal mouthfeel and taste.
  • Additional ingredient integration: The secondary fermentation is the perfect time to incorporate additional ingredients, like fruits, hops, or spices. The flavors have time to meld more seamlessly into the brew, enhancing the depth and nuances of the beverage.

On the other hand, a few downsides include:

  • Risk of contamination: Without proper preparation, the transfer process can spoil the batch by introducing various contaminants.
  • Potential oxidation: Transferring the beverage to the second fermenter can expose it to oxygen, opening the door to off-flavors and spoilage.
  • Increased time and effort: Completing a second round of fermentation requires additional time and careful monitoring.

Beverages That Can Be Fermented Twice

Various beverages sparkle after undergoing secondary fermentation, achieving a crisper, more balanced drink. These beverages include:

  • Mead secondary fermentation: This beverage benefits significantly from secondary fermentation, as flavors have time to mellow out and integrate more fully.
  • Beer aging: Many beers, including ales and lagers, develop better clarity and stability through secondary fermentation.
  • Cider secondary fermentation: The second round of fermentation can enhance flavors and clarify the beverage, resulting in a cleaner, crisper drink.
  • Secondary fermentation wine (malolactic fermentation):  Secondary fermentation helps develop more complex flavors and enhance clarity and stability.

Final Thoughts

Despite its challenges, secondary fermentation offers substantial benefits. It can elevate the quality of a brewed beverage, achieving a more refined product with a sophisticated flavor profile. Secondary fermentation can help transform a good brew into a great one, bringing depth, clarity, and a polished finish to brewed beverages.

Quantiperm does not offer products for secondary fermentation but we offer other fermentation monitoring devices. You may be interested in our FermAT system to assist with fermentation monitoring or Fermentation Monitor (FMS) to multiplex multiple fermentations (up to twelve at a time) into a single measurement system. Contact us to learn more about our innovative brewing products and services.