Yeast has been in the service of humanity for millenniums and science about yeast is so fascinating. Such small organisms can produce the healthiest and most enjoyable foods and beverages for mankind.
In this article, We’ll determine how much yeast should you use in your homebrewing processes and other important factors related to the yeast.
So, how much yeast do you need?
You should add 0.4 oz (11 grams) of dry yeast per 5 gallons (23 liters) of homebrew for a healthy yeast culture. It’s also possible to add less than it, but you are risking the efficiency of fermentation that way unless you know what you are doing.
This is the basic understanding you should have, however, this demands additional explanation because things are not always as clear as they seem at first.
What yeast does do in a beer?
Yeast is one of 4 fundamental ingredients that go in beer. It produces alcohol (ABV) and CO2 by eating sugars in the wort. Yeast is the decisive factor for fermentation success and without it, we wouldn’t have any fermented products such as beer, vinegar, wine, or bread.
In beer making, it is possible to accidentally destroy yeast and It’s important to keep an eye on its culture to keep it healthy because healthy yeast means a good brew, remember that!
Yeast is used during primary fermentation where it eats a large amount of sugar to transform it into alcohol, but also during bottle priming when it eats additionally added sugar to produce Co2 and trap it within the bottle.
It’s important not to commit big mistakes during fermentation if you desire a great homebrew!
What happens if you don’t add enough yeast?
The lack of yeast in wort will affect the fermentation in a negative way. First, fermentation may not even begin if yeast is sufficient, but even if it does it won’t be complete.
The lack of yeast means that most of the sugar that you put in a wort through malts or actual sugar if you use beer extracts, won’t be processed.
As a result, you will have sufficient alcohol percentage in your beer and it will taste extremely sweet.
In other words, you will not have a beer, mead, or cider complete, and if you do it will be bad.
Moreover, the lack of yeast affects the fermentation quality, so even if your homebrew manages to fully ferment, the lack of yeast in the initial pitch may stress the yeast and cause off-flavors.
What happens if you add too much yeast?
Contra to the situation where your wort lacks yeast, adding too much of it won’t hurt it.
Pitching extra yeast can be beneficial in some cases when you are not sure whether the environment will support the fermentation or if you have lots of complex ingredients in a wort.
For instance, heavy beers or meads with lots of honey may have so much sugar that the yeast can not process it without support. It will eat some sugars with ease in the first days, but it will struggle with the rest and the fermentation won’t complete.
You can support the yeast colonies by pitching more yeast because they’ll have an easier time reproducing and eating sugars just as it would be easier for a team of 8 to dig a 100 feet hole than for a team of 3. However, 11 grams per 5 gallons is enough yeast to do its job within 10 days, unless we are talking about some special recipe with high ABV.
The point of the story is that you can’t pitch too much because once the yeast is done it will go dormant and no matter how much you add it won’t affect anything in particular.
Moreover, you can also support yeast with the yeast nutrients but this is only used with meads or some heavy beers that lack natural nutrients from the grains.
Furthermore, If yeast does not have a steady temperature to work with, you shake it, expose it to air during fermentation, or do similarly bad things to it it will also struggle to do its job.
Another problem can occur if the wort is contaminated, in which case the bacteria may fight off the yeast cells and dominate them.
In any of these cases, pitching extra yeast (11 grams is still enough per 5 gallons) will mean stronger offense and defense for the yeast cells.
If you pitched enough yeast and are unsure did the fermentation start you can read more about it in my article about how to tell if your brew is fermenting.
How to have a successful fermentation
Re-hydrate dry yeast
Rehydration of dry yeast is not necessary, but it’s a good practice. You can read more about the importance of re-hydrating dry yeast before pitching, but in short, it helps the yeast to better adapt to an environment full of sugars. Without rehydration, some yeast may die when pitched and it may not be as effective.
Pitch yeast at the right temperature
If the wort is not cold enough, do not pitch the yeast! Every yeast type is different and works better at different temperature ranges, moreover, some yeast is more sensitive to temperature than others.
Keep the temperature stable
Yeast has its temperature range under which it can work, although this means that it should ferment within that range, big oscillations are still a problem, so once you determine what temperature It will be, do not let it oscillate more than a few degrees for best results!
Air the wort after pitching the yeast
Air is bad for your fermentation, but only once the fermentation begins! Before starting the fermentation you should aggressively shake your fermenter or artificially pump oxygen in.
This will trap oxygen within the wort mix the yeast and help the yeast to start fermentation sooner.
Final take
Yeast is an essential ingredient in homebrewing, but it has a unique ability to multiply from small colonies to big colonies as long as it is fed sugar and nutrients.
This unique ability is the reason why sometimes even a small amount of yeast can lead to a fully fermented homebrew.
Sometimes we under-pitch and sometimes we pitch too much, and while it’s better to pitch more than not to pitch enough, it can be costly.
Under-pitching can lead to yeast stress and cause incomplete fermentation, so if you are unsure whether you pitched enough or not, it’s safe to add just a bit more yeast to be sure.
Don’t count on yeast’s ability to multiply because there are many factors that affect this and yeast strains can differ from kind to kind!