Home Beer Brewing: Secondary Fermentation

Fermentation is the process which gives beer its alcoholic content. Basically, fermentation is the process in which yeast is used to convert carbohydrates to alcohol. Once you brew your batch of beer, it is put in to a fermentation container. Different yeast is used for different types of beer, so the fermentation temperatures and durations vary from batch to batch.

Once your beer is fermented, there is something else called secondary fermentation. As beer ferments, yeast seeks to the bottom as it dies. Not all yeast is used during the primary fermentation process. With secondary fermentation, you transfer the beer to another container and leave the dead yeast behind. As secondary fermentation happens, the rest of the yeast dies and your beer becomes less cloudy and more flavorful. Secondary fermentation can be done in another container, but it can also happen in the bottles as your beer ages. That is why often times you see yeast sediment at the bottom of your beer bottles as the aging process unfolds.

There are several benefits that come with secondary fermentation. One prominent one is that the taste is improved. Your beer will have more purity because the yeast sediment is no longer present. As a result, the flavors are magnified and the beer is clearer. Yeast can spoil the flavor of the beer as well, so the less yeast the better. You are giving your beer a purer finish by using secondary fermentation.

There are things you should know about this process as well. For one, most of the actual fermenting will take place during the primary fermentation. Therefore, you want to make sure you follow the instructions for that process. Keep an eye on the specific gravity to make sure the beer is done. If you rush that process, you could ruin the batch. Remember, this is where most or all of the alcohol conversion takes place. Secondary fermentation is about making the beer clearer and purer, not increasing the amount of alcohol. Therefore, depending on the type of beer you make you may decide that the process is not worth the time.

Secondly, while beer can continue to ferment in bottles, if you are planning to try secondary fermentation it is best to use it as a middle step. Once primary fermentation is complete, siphon your batch of beer in to a new container. The best type of container for this is a called a carboy. It will allow you to see how the beer looks and help you monitor the process. A carboy is basically a glass container that is usually around five gallons in size.

If you are planning to use kegs instead of bottles, secondary fermentation may not be worth the effort. Kegs will take care of the clearing process efficiently if you use proper carbon dioxide pressure as well as storing at cooler temperatures. Kegs are recommended for more advanced brewers since they are a little more complicated to use than bottles.

If secondary fermentation is something you want to try, remember the purpose the process serves. Secondary fermentation will make your beer clearer and decrease the chance of some flavors appearing that you don’t want. If you are going to try secondary fermentation, do not cut the primary fermentation process short. Use a hydrometer to make sure the specific gravity is correct before transferring the beer to your secondary fermentation container.