There’s nothing as important as fermentation in process of brewing beers or making ciders, meads, and wines.
Sometimes, due to many factors, the fermentation may get stuck and interfere with our plans, so we must be ready and have a few tips by hand to unstuck it.
The majority of our brews at brewing way pass well because we ensure the yeast has all the essential tools to start and ferment to the end without interruption, but there were instances when we weren’t so lucky.
I’ll share a few useful tips, so you can instantly unstick your fermentation.
Before you do anything it’s important to check the current state of the fermentation and environmental factors.
Try to answer the following questions first.
1. Is the temperature right for the particular yeast strain you are using?
Temperature plays the biggest role in how well the yeast performs. If it’s too cold, the yeast will be sluggish and take longer to ferment and it could even go dormant.
2. Are there big oscillations in temperature?
If there are big drops in the temperature during the day or night, it could confuse the yeast and create a similar problem as I mentioned in the question above.
3. Did you pitch enough yeast at the beginning?
Underpitching of yeast can result in the yeast not establishing a strong colony which can result in failed or slow fermentation and sometimes it may contribute to off-flavors. This especially plays a role when there are many sugars typical for heavy beer, mead, or cider styles that should end up with high alcohol content.
4. What was the temperature at which you pitched yeast?
Did you accidentally kill the yeast by pitching it at the wrong temperature? Yeast strains can die if you pitched at temperatures above 86°F (30°C), especially if the yeast was previously cooled below room temperature and the sudden temperature change caused a shock.
This is similar to what happens to people who jump into the cold water on a hot, summer day and get a heart attack. Their hearts didn’t have time to adapt to the new temperature and thus it caused a shock.
5. Did the yeast expire or was stored at a too-warm temperature?
Yeast can survive for years on the shelf, but only at the right storing conditions. Yeast can be stored at room temperature but shouldn’t be exposed to warm temperatures over a long period of time. Ideally, the yeast should be stored at cooler places below room temperature for best results.
6. Did you supply the yeast with nutrients?
Yeast needs nutrients to work or it doesn’t have a way to reproduce. Just as a child needs nutrients to grow, so does yeast.
There are plenty of nutrients in beer worts as the grains naturally contain plenty of nutrients. There is although less than in grains, plenty of nutrients in fruit juices used for making ciders most of the time, and there’s often a lack of nutrients in honey used for mead making.
7. Did the airlock bubble at any point?
If at any point during fermentation the airlock bubbled, it means the fermentation did start because the bubbling airlock is a sign of Co2 escaping from the fermenter. This is good news as it could mean the yeast isn’t really stuck or it just needs a slight push to continue to ferment in case it got stuck for some reason.
8. Have you taken and compared gravity readings?
The most accurate way to tell did fermentation begin and how much sugars are fermented is by taking gravity readings.
This way you’ll know exactly at which point the fermentation got stuck.
For instance, if the fermentation got close to a desired final gravity of 1.010, so it stopped at 1.015 when you measured, it’s not the same as if the specific gravity was at 1.030 after 10 days and the original gravity was 1.040.
Sometimes just a bit more time could be required, but if the difference is huge after plenty of time it means the stuck fermentation is more of a problem.
How to unstick fermentation
After you answered the questions above, you’ll have a good understanding of what might be going on.
Now, it’s important to take care of the problem by following the tips below.
You’ll know best what’s the matter, so try to diagnose the problem as well as you can and apply the method by method, starting with the easiest solutions first such as adjusting the temperature or giving it more time to unstuck on its own.
If those don’t unstick the fermentation you’ll need to pitch new yeast, add nutrients, or fix whatever step you missed during the initial setting of the fermentation.
1. Adjust the temperature
Every yeast strain has its own temperature of preference, so if this was the problem for your stuck fermentation, just adjust it and it should yield the results within 24 hours.
The warmer the temperature, the more active the yeast will become, just don’t go above the yeast fermenting temperature range as it could create off-flavors such as a harsh alcoholic taste from fusel alcohols or a very fruity taste from esters.
It’s also possible to damage your yeast if you increase the temperature above 86°F (30°C), as barely any yeast finds that temperature attractive.
I have written an article on how to control the fermentation temperature, so if you are experiencing such problems check it out.
2. Give it more time
If everything is fine, or you adjusted a few things that were a potential reason for stuck fermentation, just give it more time.
Some yeast strains are fast workers, and some are lazy, but eventually, every yeast strain should finish the job.
For instance, I love to use SafAle S-04 above many other ale yeasts because it ferments my ales within 3 days, which is truly amazing.
Right now while I am writing this article, we are completing a Pilsner with a bottom-fermenting yeast, it took 2 weeks for the beer to finish fermenting.
Ciders and meads also take more time on average to finish but as long as the ABV isn’t expected to be high, most yeast strains will finish the work within 10 days.
3. Pitch extra yeast
If you underpitched yeast in the first place then the obvious fix is to pitch extra yeast as this will mean fresh and strong colonies.
However, even if you didn’t under-pitch but suspect that the yeast could be dead for any of the reasons mentioned above, it’s important to pitch new yeast.
What’s cool about the situation in which the old yeast died is that it will now serve as a nutrient for newly pitched yeast!
It sounds crazy but the best yeast nutrient is actually dead yeast as it’s full of vitamins and other good stuff the yeast loves.
See, it’s not that dark!
4. Add yeast energizers and nutrients
Yeast nutrients are a great addition at beginning of every fermentation and can be added even if there are plenty of nutrients from the grains or juice already, as they can’t hurt but only increase the odds of healthy and successful fermentation.
Thus, add some nutrients when pitching yeast if you feel there’s a need to.
On other hand, if you are dealing with a stuck fermentation you should add the energizers instead.
Energizers are similar to nutrients but a bit more pricey, and they also contain more useful compounds that might be needed when the yeast really needs that extra help.
Look at energizers as the medicine for your yeast, sometimes the yeast needs first aid when nothing else helps.
4. Give it a swirl (but carefully)
It’s told that shaking things up can benefit unstuck fermentation as you can force yeast to get to work.
Although I didn’t find this to ever help me, some homebrewers claim that it works.
I believe that this is bad advice if your fermentation got stuck somewhere in the middle or by the end as introducing extra oxygen will lead to oxidation.
However, oxygen is beneficial prior to fermentation begins as it can be used as a nutrient and lead to a healthy fermentation.
So, stir it a bit if the fermentation didn’t begin at all but otherwise stay away from this practice.