Will Adding More Yeast Speed Up Beer Fermentation?

Fermentation, a crucial part of the brewing process, occurs when yeast converts sugar into alcohol. Is there a way to speed up fermentation? 

Adding more yeast to fermenting homebrew beer will not speed up the process of fermentation. However, using yeast starters and ensuring the wort is at an ideal temperature (around 68 °F) when pitching can help fermentation get started more quickly, reducing total time in the fermenter.

Read on to learn more about adding yeast to beer, whether or not it can add alcohol content, and a few things that you can do to help speed up your homebrew fermentation.

Does adding more yeast make beer ferment faster?

Yeast is a living organism, and has the ability to go “dormant”. This can happen when the yeast gets too cold, or is sitting for too long. When fermenting beer, you will want to keep your yeast active by letting the yeast hang out at or around room temperature. 

In order to speed up the beginning stages of the fermentation process, you can make what’s called a yeast starter. A yeast starter is simple to make. By boiling water and malt extract, waiting for it to cool, and combining it with liquid yeast, you will have made your yeast starter. (Some brewers suggest adding hops, but it is not necessary for a true ‘starter’.) 

Airflow is key when making a yeast starter, and you are going to want to leave it in a beaker-like vessel without a top to allow oxygen to flow and aerate the solution. If you need to, use a foam stopper or a thin piece of muslin fabric over top so as not to completely cut off the oxygen supply. 

After 24-48 hours the yeast will have propagated, forming your starter! 

If you don’t feel like making this yourself, there are yeast starter kits like this one available on the market.

Does adding more yeast increase alcohol content?

During the fermentation process, the yeast is converting the sugar into alcohol, as we have discussed. So in theory, if there is not enough sugar for the yeast to convert into alcohol, your ABV will not be higher. 

Adding more sugar, however, will get you a higher ABV. Be careful though, as you will find that your beer can dry out considerably.

5 ways to speed up fermentation

Speeding up the fermentation process should be done with caution, and an understanding of everything that could go wrong. 

“Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.” The quote is from Dr.Ian Malcolm from Jurassic Park, but it applies here as well. Just because you can speed up the fermentation process does not necessarily mean you should. 

Higher temperatures can make a beer ferment too quickly, but this can lead to off-flavors. There are certain beers that naturally ferment faster, like ales, since they’re intended to ferment at the higher temperatures on the spectrum. 

You can also end up with green beer if you’re not careful, because the yeast has not finished doing its job. Part of the yeast’s job is to do a clean up of sorts, and when they are worked too hard they will become too strained to finish the job. 

Use a yeast starter to begin fermentation faster

We talked about how to make a yeast starter, but how do they work? Yeast can become distressed or overworked, much like people can. They are living organisms, after all. The purpose of making a yeast starter is to allow the yeast organisms to multiply. This takes the strain off of the yeast that is already working, the more live yeast organisms, the more help they get fermenting. 

Brewer beware, starters commonly give off the strong smell of sulfur when they are working. Do not assume that your batch has gone bad, this is completely normal and should go away relatively quickly. 

Make sure your beer isn’t too cold

High temperatures will make beer ferment quicker, and conversely low temperatures will cause it to ferment slower. 

Yeast organisms don’t like the cold, anything colder than around 68 °F and you’re approaching the danger zone. At lower temperatures, there is a greater risk of your yeast going dormant. This does not bode well for your brew, once the yeast stop converting sugar into alcohol

Know your batch size

A 3-gallon batch vs a 10-gallon batch will take about the same time to ferment. However, if you need to adjust the temperature at all,  3-gallon batch will heat up (or cool down) more quickly than a 10-gallon batch. 

While it might seem more cost effective to brew 10 gallons at a time, consider sizing down in order to have more control over the factors that affect fermentation speeds. 

Low ABV beers

The lower the ABV, the quicker the fermentation process. Lower ABV means less work for the yeast, and therefore a quicker turnaround. As discussed, less sugar for the yeast to convert, less time it takes for the yeast to finish converting. 

As with everything else, it will not just be one factor that affects your fermentation period. Everything comes into play, including alcohol content. 

Kegging and force carbonating can speed up fermentation

Kegging your beer can shave a few days off of your fermentation time. When bottle conditioning, the yeast needs at least a few weeks to convert the priming sugar from the bottles to alcohol. 

If you bottle condition though, try to keep your bottles somewhere a little warmer. Around 80F at least until the yeast has converted the priming sugar, at which point you can store it at a lower temperature. 

Adding more yeast can speed up the fermentation process

But it is not the only way to speed up the fermentation process. There are many forces at play here, and manipulating any of them even in the slightest can speed up (or slow down) the process of fermentation. Using a yeast starter can jump-start the process for you, though!