It’s happened to the best of us: we’re excited and ready to start a new homebrew project, we’ve boiled the wort and lugged out our carboy only to discover that our packet of yeast is expired, dead, or missing. Is all hope lost? Can we just substitute some of the bread yeast we found sitting unopened in the pantry?
You can technically use bread yeast to make beer because it will metabolize available sugars during fermentation and produce carbon dioxide (CO2) and alcohol just like beer yeast. However, bread yeast will generally create a poor-quality beer with added off-flavors, cloudiness, stuck fermentation, and too much carbonation.
To learn more about yeast and pick up tips for your own baker’s yeast experiments, keep reading!
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Is it possible to use bread yeast to make homebrew beer?
If you’re expecting to use bread yeast as a quick substitute for brewer’s yeast, you may be disappointed with the results. However, learning to homebrew with bread yeast can teach you a lot about the numerous ways yeast can impact beer.
It is absolutely possible to make homebrew beer using bread yeast. For the most part, bread yeast and beer yeast are the exact same species and undergo the same chemical process used to convert sugar to alcohol: ethanol fermentation.
Of course, beer yeast has been bred specifically for brewing and therefore has a few features that bread yeast might lack.
For instance, bread yeast is:
- less prone to clumping together
- ferments faster and more aggressively
- produces different flavor compounds than brewer’s yeast
What kind of alcohol does bread yeast make?
Before attempting to brew beer with bread yeast, you might wonder if it will produce a completely different type of alcohol.
Just like any other yeast, bread yeast produces ethanol through ethanol fermentation. In addition, both bread yeast and beer yeast can synthesize trace amounts of higher alcohols like propanol and butanol as by-products of ethanol production.
When baker’s yeast is used for breadmaking, it begins in an aerobic environment where it will ferment sugar and oxygen to make carbon dioxide and water. It’s not until the carbon dioxide completely saturates the water in the bread that the yeast breaks down sugars in the bread into alcohol and carbon dioxide. The fermentation process is responsible for the bread rising.
When introduced to a low-oxygen environment (like the kind found inside an air-locked carboy) bread yeast will immediately begin ethanol fermentation just like beer yeast would.
Could you use active dry bread yeast to fix a stuck fermentation?
While it may seem intuitive to add more yeast when a batch of beer stops fermenting, lack of yeast is rarely the cause of a stuck fermentation.
Although adding extra yeast will not solve all the reasons for stuck fermentation, If your stuck fermentation is due exclusively to a lack of yeast, adding dry bread yeast will certainly restart fermentation. That being said, adding bread yeast will alter the flavor and behavior of your beer just as if you had pitched baker’s yeast to begin with.
To find out more about how to restart stuck fermentation before turning to bread yeast, read my complete breakdown on how to reset stuck fermentation.
Before you even consider opening a packet of bread yeast to restart your fermentation you should consider other common reasons your homebrew might have stopped bubbling. For example, fermentation can stop due to low levels of aeration or insufficient nutrients.
What is the difference between bread yeast and beer yeast?
Most yeasts used in fermentation are part of the same species complex, Saccharomyces sensu stricto. Of these, S. cerevisiae is by far the most common. This species is also incredibly diverse, accounting for over 651 strains with 575 distinct genotypes responsible for the unique flavor profiles of bread, sake, wine, beer, cider, and other fermented foods.
When it comes to comparing bread yeast and beer yeast, there are a number of factors that differ between the two categories.
Here are the most important aspects of yeast to consider when comparing the two types of yeast:
- Flavor Profile
Most beer and bread yeasts come from the exact same species of yeast, S. cerevisiae. However, the history of their development differs widely.
Beer yeast colonies have been selected and maintained over thousands of years by dedicated brewers working to perfect their craft. Conversely, bread yeasts were only produced industrially in recent history and have no history of careful domestication.
The main difference between these yeasts comes from the different ways in which they were used. Throughout history, brewers harvested and reused yeast from successful batches of beer in a process called backslopping. This was done year-round and in almost complete isolation from other yeasts, resulting in numerous distinct strains with attributes perfectly suited for different beer-making traditions.
In contrast, the yeast used by bakers was rarely maintained year-round. Even when yeast colonies were maintained as a sourdough starter, they were constantly in contact with foreign, wild yeasts that could change the genetic makeup. For these reasons, bread yeasts exhibit a much wider genetic and geographic diversity than that seen in brewer’s yeasts.
Although baker’s yeast is defined more by similar traits than genetics, all modern industrial bread yeasts come from the species S. cerevisiae. Beer yeasts tend to be more genetically homogenous, yet paradoxically also include yeast from other closely related species.
Other yeast species used in brewing beer include S. bayanus, S. paradoxus, and S. pastorianus. Other beers feature a yeast from an entirely separate, but related, genus: Brettanomyces. Yet even these yeasts have been maintained and selected for over centuries of domestication by brewers and maintain high genetic stability.
Baking yeast on the other hand have very little genetic similarities with one another, with some showing strong similarities to wine yeasts and others appearing much more similar to the yeast used to make beer. Rather than genetics, baking yeast is defined by similar features, specifically the ability to break down complex sugars, the ability to adapt to a rapidly changing environment, and the ability to survive anaerobic conditions.
While the bread yeasts you find in the store are rarely related, they are unlikely to continue evolving. Modern industrialization of yeast production requires strict quality controls, meaning that factories maintain their yeast under highly controlled conditions similar to those beer yeasts have been subjected to for centuries.
One of the most important factors for yeasts used in alcohol production is the ability to survive high levels of alcohol.
While some strains are able to withstand ethanol levels up to 18%, there is actually very little difference between the alcohol tolerance of bread yeasts and beer yeast.
Because beer is usually brewed to be less alcoholic than other fermented beverages like wine or sake, even less hardy species of yeast that can only withstand between 8 and 14% alcohol content are perfectly suitable for beer making. Alcohol tolerance is not particular to any one strain or species of yeast, and commercial bread yeast is just as comfortable within this range as most brewer’s yeasts.
Flocculation describes a yeast’s tendency to clump together in large sheets.
Flocculation is incredibly important for clarifying beer but completely irrelevant for baking, making this one of the most significant differences between brewer’s yeast and baker’s yeasts.
Just like alcohol tolerance, flocculation is controlled by an unstable gene that is not particular to any one type of yeast. But while beer makers bred yeasts to clump together for easy removal after brewing, bakers do not need to remove yeast from their bread and would therefore have no reason to seek out this trait.
This means that while it is possible for baker’s yeast to aggregate for easy removal, it is far more likely to leave your beer hazy and filled with debris. Therefore, if you want a clean, clear beer made from baker’s yeast, you will probably want to invest in a filter.
Attenuation describes the efficiency with which sugars are broken down during fermentation.
The attenuation of different yeasts is deeply dependent on a number of environmental and genetic factors, but in general baker’s yeast will produce drier, more alcoholic beer than brewer’s yeast.
Bread yeast has been shown to be extremely quick and efficient in breaking down glucose and maltose, and will therefore produce more alcohol and carbon dioxide than standard beer yeasts. This feature will be compounded by their lower levels of flocculation, which will further increase the extent of fermentation.
However, attenuation has just as much to do with environmental factors as genetics, so the temperature, consistency of your mash, and pitching rate will all affect your final gravity.
While experimenting with bread yeast, I recommend that you brew your beer at a slightly lower temperature than you’re used to. This will lower your attenuation to more closely reflect the levels you’re used to while lowering the risk of developing off-flavors from the bread yeast.
Since the ideal flavor of yeasted bread is very different from a well-balanced beer, homebrew made with baker’s yeast may run the risk of developing unusual or off-putting flavors.
Not all bread yeasts are alike, however, so your flavor profile will vary depending on the exact strain of baker’s yeast used.
The flavors beer makers have bred in brewer’s yeast feature light, fruity aromas. Even in darker beers, we prefer flavor compounds reminiscent of apples and honey, like phenyl ethyl acetate, ethyl caproate, ethyl caprylate, and ethyl acetate.
Our preference for fruity aromatics is so strong that we label savory flavors (ie. yeasty, buttery, or cheesy flavors) as undesirable, even if we would seek out those flavors in a loaf of bread.
You will have to prepare for some of these savory aromas if you decide to brew with bread yeast since bakers do not have the same aversion to savory flavors. But baker’s yeast is an incredibly diverse category, and while many commercial bread yeasts will produce large amounts of buttery 2,3-butanedione and alcohol-forward 1-propanol, others have been shown to produce the floral, almondy aromas associated with phenyl ethanol and 2-phenyl ethanol.
How do I brew with bread yeast?
Because of the genetic diversity seen between commercial bread yeasts coupled with their slightly different behavior when compared with beer yeasts, you’ll have to be prepared for an experiment if you decide to pitch baker’s yeast.
If you decide to brew with bread yeast, treat it as an experiment and a learning opportunity to become more aware of the role that yeast plays in the brewing process. Stick with one brand of commercial baker’s yeast and prepare to set down your recipe and rely on your intuition as a brewer.
Because both yeasts are the same species and ferment sugar through the same process of ethanol fermentation these experiments will be about fine-tuning the brewing process, not about completely re-learning to homebrew.
How much to pitch
While experimenting with the amount of bread yeast to pitch, you’ll want to make changes slowly.
I recommend pitching the same amount of yeast you would use in a recipe that calls for normal beer yeast and brewing at a slightly colder temperature than you’re used to. This will ensure that you don’t under-yeast your beer while relying on temperature to reduce the off-flavors and slow the attenuation to a level more closely in line with brewer’s yeast.
While over-yeasting can produce off-flavors, under-yeasting is far more common on a homebrewing scale. In addition, over-yeasting will have a negligible impact on the final gravity of your beer.
While it’s generally a good idea not to over-yeast your beer, studies have shown that adding too much yeast has almost no negative impact on beer. The major exception to this was the production of buttery diacetyl compounds as yeast competes for insufficient nutrients.
How long to ferment
Bread yeast will finish primary fermentation faster than beer yeast, but the exact length of fermentation will depend on the exact strain you use. To overcome this problem, you’ll want to rely on visual cues to let you know when your brew is done fermenting.
While we don’t usually think of bread as something that contains alcohol, bread yeast is actually incredibly efficient when it comes to fermentation. Because bakers prefer yeast that starts fermenting immediately and saturates dough with alcohol quickly, you will probably see a faster, more intense primary fermentation than you’re used to with brewer’s yeast.
In addition, because bread yeast strains will ferment at different rates, you’ll want to pay attention to other signs that primary fermentation is finished.
The strain of yeast chosen for secondary fermentation will have a huge impact on the effectiveness of bottle conditioning.
Most yeast produce similar levels of carbon dioxide when given enough time, so your best bet is to add the same amount of yeast as you normally would and tweak the formula based on your own observations and experiments.
According to research published in 2020, the amount of carbon dioxide produced by baker’s yeast was almost identical to the amount produced by non-baker’s yeast. The main difference noted between the two came down to the speed of fermentation, suggesting that bottle conditioning may reach completion faster with bread yeast than beer yeast.
Along with the speed of fermentation, the biggest difference between yeast strains used for secondary fermentation comes down to the production of volatile flavor compounds.
Both of these factors will influence the effectiveness of bottle conditioning, but while identifying the flavor compounds produced by different strains of baker’s yeast will take time and experimentation, there are a few tricks you can use to judge whether or not your secondary fermentation is complete.
Read more about my suggestions for tracking your bottle conditioning here.
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