How to tell if your beer wort fermented properly

Thursday, November 2, 2023
Fermentation is a crucial process in the beer-making journey, transforming a simple concoction of water and malt into the delightful beverage we all know and love. Without fermentation, your beer remains a 23-liter bucket of watery malt, void of the complex flavors and alcoholic content that define beer.

During the fermentation stage, homebrewers often encounter various challenges. A common concern is the absence of visible signs of fermentation, such as the lack of bubbles in the airlock. However, it's important to note that the absence of bubbles doesn't necessarily equate to a lack of fermentation.

The fermentation process can take a minimum of 15 Earth hours before the CO2 bubbles make their appearance through the airlock. Hence, patience is key. If you suspect your beer hasn't started brewing, there are several steps you can take to troubleshoot the issue.

how to tell if beer wort fermented correctly

For those using glass fermenters, inspect the interior for a dark scum that typically forms around the water level mark. This scum is a telltale sign of fermentation and can often be seen through the standard white fermenter drum. Similarly, the presence of foam, or 'krausen', is another indicator that your beer is fermenting as it should. Be sure to give it between 20 to 48 hours before you begin to worry.

In the case of plastic drums, the process is slightly different. If the drum is transparent, you can visually inspect it for the presence of scum. Alternatively, you can remove the airlock and peek through the hole to check for scum or foam.

A common mistake made by homebrewers is not sealing the fermenter properly. If the fermenter is not sealed tightly, CO2 can escape through the lid rather than the airlock, preventing the build-up of pressure necessary for gas to pass out of the water trap.

The location of your fermenter is another important factor to consider. Yeast, a crucial component in the fermentation process, becomes inactive in cold temperatures. Therefore, it's essential to ensure that your fermenter is stored in a warm place, away from cold sheds or garages where temperatures can drop to zero degrees centigrade.

A hydrometer is another useful tool that can help you determine whether your beer has fermented. A beer is typically considered fermented when the final gravity reading is 1/3 to 1/4 of the original gravity. This, of course, requires that you took an initial gravity reading before starting the fermentation process. 

If the readings remain the same over a 24-hour period, you've reached your final gravity, indicating that fermentation is complete.

wort fermentation completition


Once fermentation is complete, resist the urge to bottle your beer immediately. Allowing it to mellow for a longer period will result in a better-tasting, clearer brew. This is especially important for beginner brewers who may lack the patience to wait. Remember, brewing is a game of patience, and those who wait are rewarded with the best results.

But what if there are still no bubbles in the airlock? The most likely culprit is a leak that allows CO2 to escape. Ensure that your drum is tightened properly and that the tap is screwed in correctly. If you've checked for leaks and found none, the issue could be temperature-related. Ensure your beer is stored in a warm enough place, especially during the colder months.

For those brewing in winter, consider wrapping your fermenter in blankets or old sheets to keep it warm. This trick is particularly effective if the beer is already at an appropriate brewing temperature. Alternatively, you could store your fermenter in a warm place inside your house, such as the kitchen or living room.

correct fermentation of wort beer



Heat pads or panels are also popular options among brewers for maintaining a consistent brewing temperature. If you choose to use a heat pad, ensure that your brew is stored close to a power socket.

Lastly, yeast failure could be another reason for a lack of fermentation. Using fresh ingredients is essential, as old or dry yeast may not activate properly. When adding yeast, ensure that the solution is at the appropriate temperature, as specified in the beer kit instructions. Avoid adding yeast to boiling water, as this will kill the yeast and prevent fermentation.

In summary, here are some troubleshooting tips for homebrewers facing fermentation issues:
  • Check for leaks that may be allowing CO2 to escape.
  • Look for the presence of foamy residue or scum, both indicators of active fermentation.
  • Ensure that the fermenter is stored at an appropriate temperature for the type of beer you are making.
  • Consider using a heat pad to maintain a consistent brewing temperature.
  • Always use fresh ingredients and add yeast at the correct temperature.
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