Secondary Fermentation

A couple of decades ago there was a consensus among brewers that secondary fermentation of beer was a must. Much has changed since then, new technologies and equipment have appeared, and beer has been brewed in a new way. Today, the debate about the appropriateness of secondary fermentation is still raging. Some argue that secondary fermentation is unnecessary, while others, on the contrary, consider this stage an important part of the process. 

What Is Secondary Fermentation?

Transferring beer from the original fermentation vessel to a secondary vessel for additional fermentation and conditioning is known as secondary fermentation in beer. The kind of beer being brewed, the yeast strain being utilized, and the temperature of the fermentation vessel can all affect how long the secondary fermentation process takes. During secondary fermentation, the beer develops its final flavor and carbonation. The process can help to clarify the beer, as well as improve the flavor and overall quality, resulting in a smoother and more refined finished product.

Secondary fermentation can be especially useful for high-alcohol beers or beers that require extended aging periods. Secondary fermentation can take anything from a few days to many months to complete. The process can also help to clean up the beer and mellow out any harsh or off-flavors.

The addition of wort or sugar solution to a conditioning tank can aid in secondary fermentation. In a bottle, a secondary fermentation is performed, resulting in a natural carbonation process. It is recommended to transfer the beer to a CO2 purged keg fitted with a spunding valve with 1-2% of extract remaining, and raise the temp to 5°F higher than the fermentation temp to allow the beer to secondary there. The residual yeast transferred with the beer consumes any O2 inadvertently introduced, finishes fermenting the beer, and cleans up any byproducts.

Is Secondary Fermentation Necessary?

The theory behind transferring beer to secondary or tertiary fermentation is the need to separate the beer from the sediment as soon as possible after active fermentation. Dead yeast cells, suspensions from hops, and grains transferred from brewing and active fermentation can impart unpleasant flavors and aromas if they remain in contact with the beer for too long. The fact that many home brewers use buckets or bottles for fermentation means that quite a large surface area of the sludge is in contact with the beer.

In addition, overflow for secondary fermentation gives brewers a great opportunity to stock the yeast for rinsing and reuse.

Benefits Of Secondary Fermentation

The benefit of secondary fermentation is obvious and comes from the separation of the beer from dead yeast cells, suspended hops, and grains remaining after brewing, as well as tannins, which during primary fermentation settle as sediment at the bottom of the fermenter. All of this can introduce undesirable flavors and make the final product turbid. Part of the problem is alleviated by the use of ready-made malt extracts, which produce a fairly clean and clear wort, but yeast sludge will form in any case. This yeast, lying on the bottom in large quantities, can begin to die and decompose. This process, called autolysis, produces its own irrelevant bouquets of aromas and flavors in a good beer.

Secondary fermentation problems

The main problem with secondary fermentation is the risk of oxidation. When you pour the beer into another container, it is enriched with oxygen, which is highly undesirable. Even a small amount of oxygen can ruin the beer permanently.

The second problem is the possible risk of bacteria contaminating the beer, which can lead to the souring of the product.  Transferring beer for secondary fermentation requires a good understanding of the process, for example, a lack of yeast in the beer can negatively affect the further fate of the drink.

Many brewers prefer not to get bogged down in the intricacies of the biological carbonation process and only pump the beer once. On the other hand, young beer contains diacetyl, which in excess can give the beer an undesirable taste.  Secondary fermentation of beer at home allows the diacetyl to be broken down and the taste of the beer to be preserved.

Primary vs Secondary fermentation

There are several stages in the process of brewing beer. Fermentation of the wort is done by yeast, during which time the beer acquires strength, flavor, and aroma. The sugars present in the mass are converted by the microorganisms into alcohols, carbon dioxide, etc. At the end of the process, the microorganisms precipitate at the bottom of the tank, and the intensity of the fermentation decreases.

The process of secondary fermentation of beer in home brewing 

The use of perfect technological methods makes it possible to achieve excellent quality beer even at home. The brewer must know when to put the beer for secondary fermentation, what ingredients to use for this, how to reduce the number of tannins in beer, and many other things. But in short, the main thing in primary and secondary fermentation is the correct and timely drainage of residues. If there is a need to store beer in a fermenter, it is better to use the practice of secondary fermentation. If there is no need to store the beer for a long time, the first fermentation will be sufficient without further manipulation.

The process of secondary fermentation begins by pouring the wort into another fermentation tank. Next, you need to add yeast, which can be scattered directly on the surface of the wort. You can add about 0.5 liters of ready-to-use wort left over from the first fermentation. After stirring it all up, leave it alone. It is important to ensure that the wort is draught-free and that the room temperature remains constant. The temperature of the diluted yeast and the yeast wort must not be too low or too high.

After the yeast has been introduced into the wort, alcohol is poured into the container. In this form, the container is left in a dark place for about a week. You can tell when the beverage is ready by the density of the beer, which remains unchanged for 2 to 3 days.

So what do industrial brewers do?

Almost all craft and industrial breweries now use conical fermentation tanks such as CCTs. They do not use secondary or tertiary fermentation. These tanks have a conical bottom and the yeast slides down to the bottom of the cone – allowing for easy removal of sediment. This design means that only a small amount of beer remains in contact with the sediment at the bottom of the fermenter.

Because of the conical design, the brewer doesn’t have to pour the beer into another tank to separate it from the sludge. He simply opens the tap at the bottom and drains the sludge before the beer appears. He can collect the yeast by the same method. Therefore, mini brewers do not need to use secondary or tertiary overflows even if storage takes place over a long period of time – they simply drain the sludge periodically and leave the beer in the same fermenter.

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