Choosing the Best Yeast
You’ve certainly heard the anecdote: Brewers make wort, but yeast makes beer. It’s the key to fermentation — the transformation of one thing into another delicious thing. The trouble is a side effect of a great problem to have, which is that we have so many yeast options available to us that choosing the right one feels just as hard as ordering wine off a pricey wine list. Let’s talk about considerations when choosing a yeast and then review the key numbers and terms that process includes.
Yeast Manufacturers and Selection
The first elephant in the room is manufacturer selection. When you order a beer ingredient kit from one of the big homebrewing retailers, there’s usually a drop-down list to pick a yeast. The beginner homebrewer may simply default to whatever the cheapest option is (not a bad reason!), but there could be five or more options for that particular style, including multiple options from each manufacturer! The main companies making homebrew-sized quantities are liquid yeast manufacturers Omega, White Labs, Wyeast, and Imperial, and dry yeast manufacturers Lallemand, Fermentis, and Mangrove Jack’s (though some liquid yeast suppliers are starting to roll out dry versions of their most popular strains as well). All of these have impeccable quality control and consistency. Some of us pick one and stick with it like we would a car manufacturer, but you really can’t go wrong with any of them if you take the rest of the considerations we’ll discuss next.
Liquid vs. Dry Yeast
The main distinction to navigate when selecting yeast is picking between liquid and dry yeast.
Liquid yeast offers more options so you’re able to find a variety of yeast choices for any style of beer you want to brew. Whereas you find one or two strains suitable for a saison from each dry yeast manufacturer, you’ll find a small handful from many of the liquid yeast labs, each bringing unique characteristics to the resulting beer. However, liquid yeast requires careful handling and near-constant refrigeration. Those are live cells living in suspension, patiently waiting to be fed! If you receive a swollen liquid yeast pouch, it doesn’t mean it’s bad — it just means the cells have come out of “hibernation” from the cold and have started multiplying and creating CO2 inside the pouch. However, without a microscope and hemocytometer to count cells, you’re pretty much guessing about whether it’s still good to use. You could propagate the slurry in a yeast starter, but if that pouch sat in the back of a delivery van during a 104 °F (40 °C) California summer for two days, then it’s probably not worth pitching.
Dry yeast, on the other hand, is more convenient, generally costs less, and has a much longer shelf life. The technology for concentrating and drying yeast has come a long way and has become readily available to manufacturers, so homebrewers today benefit on both price and options from dry yeast labs. These packets are moisture-proof and vacuum-sealed or packed under an inert atmosphere to protect the yeast from contamination, air, humidity, and spoilage, which gives us an easy go-to option we can always keep on hand. I keep my dry yeast refrigerated, but not all brands require that and even those that suggest it should be OK if left at room temperature for a few days.
Yeast Nutrients and Proper Handling
It’s best practice to check the yeast manufacturer’s suggestions regarding nutrient additions at pitching time and during fermentation. While some yeasts may come with nutrients, most do not. High-gravity beers and lagers often require additional yeast nutrients to ensure a healthy fermentation.
One of the best ways to ensure a healthy fermentation is to properly oxygenate your wort before pitching if using a liquid yeast; dry yeast generally doesn’t require additional oxygenation. Yeast requires oxygen to multiply during the initial growth phase. For homebrewers, shaking the fermenter vigorously or using an aquarium pump with a diffusion stone can effectively oxygenate the wort. Professional brewers often use filtered air or pure oxygen injection to ensure adequate oxygen levels. Many homebrew equipment manufacturers have some pretty cool carbonation stone options when using stainless conicals with tri-clover ports.
Choosing the Right Yeast Strain
Twenty years ago, we were lucky to have one, maybe two, options for each style. Most beginner ale ingredient kits just come with the dry, shelf-stable SafAle US-05 because of its stability and consistency. Nowadays you could pick from more than a dozen strains, choosing one over another because of the final product outcomes you are seeking.
Yeast strains vary in their ester production and temperature preferences due to differences in their genetic makeup and metabolic pathways. Esters, which contribute fruity and floral aromas to beer, are primarily created through the enzymatic reaction between alcohols and acids during fermentation. Different yeast strains contain unique sets of enzymes that regulate ester formation, which is why a Belgian yeast might produce pronounced banana and clove notes while a clean American ale yeast generates minimal ester content.
Temperature plays a key role in ester production because it directly influences yeast metabolism. Higher fermentation temperatures accelerate yeast activity, leading to increased production of esters and other volatile compounds. This means that fermenting with the same yeast at the lower end of the manufacturer’s recommended temperature range will result in a different tasting beer than fermenting at the upper end of the recommended range. This is just another way to influence the final outcome of your beer that brewers must consider. The yeast cell membrane’s fluidity and stress tolerance also differ between strains, affecting their optimal temperature range. Some ale yeasts, like White Labs WLP090 (San Diego Super Ale), are selected for high-performance fermentation at warmer temperatures while maintaining a clean profile, whereas traditional lager strains require cold fermentation to suppress ester formation. Understanding these characteristics allows brewers to harness yeast behavior for precise flavor control.
Looking for a more estery profile with a hint of fruitiness? Omega’s OYL-011 (British Ale VIII) has got you covered. If you want a clean and crisp hop-forward beer, then Imperial’s A07 (Flagship) is your pick. When I’m seeking a fast turnaround and clean finish, then White Labs WLP090 is my go-to.
Those are just a few liquid options for pale ale, but the point is that yeast plays a big factor in the finished product, so the key to knowing which option to pick is by learning how they behave. Reading the manufacturer’s description is a great place to start, though it isn’t enough guidance for me. I frequently split batches and try two different yeasts on the same wort so I can compare the appearance, aroma, flavor, and finish and make my own opinions about the outcomes. When doing this, take notes of how the fermentation behaved and your evaluation of the finished beer so you have this information when selecting yeasts for future batches.
After experimenting for years, I’ve settled on specific options for my “house beers” that I keep in rotation.
Temperature Control: Yeast’s Goldilocks Zone
Yeast is like Goldilocks — it wants everything to be just right. Temperature control during fermentation is one of the most important factors in achieving consistent results. Too warm, and you can get excessive ester production, fusel alcohols, and off-flavors. Too cold, and the yeast may become stressed or sluggish, resulting in an incomplete fermentation.
For most ale yeasts, the ideal fermentation temperature is between 65–72 °F (18–22 °C). Lager yeasts typically perform best between 45–55 °F (7–13 °C), requiring additional equipment like temperature-controlled fermentation chambers to maintain steady conditions. Even when fermenting in these ideal temperature ranges, the outcome will differ depending which end of the spectrum the beer is fermented. Temperature is ideally measured using the internal temperature of the fermenter. We can achieve that with a thermowell or a temperature probe mounted to a tri-clover port or through a two-hole bung.
Understanding Yeast Numbers and Terms
There are a number of factors yeast manufacturers will list for each strain that are important to understand when choosing a yeast that will offer the desired outcomes, which we’ll dig into next:
Attenuation
Attenuation can be thought of as the yeast’s work ethic. This number quantifies the density change in the wort as the yeast converts sugars into alcohol and CO2. The level of attenuation has a direct impact on the beer’s dryness. Yeast strains can have varying levels of capability to ferment maltotriose — low-attenuating yeasts typically ferment none.
Low attenuation (65–70%): Common for malt-forward beers like stouts and porters, leaving more residual sweetness.
Medium attenuation (70–75%): Common in ales and lagers for a balanced finish.
High attenuation (75–80%): Ideal for drier beers, where we want hops to shine, such as West Coast IPAs.
Extreme attenuation (85–95%): These high levels of attenuation to ferment beer are only possible when using diastatic (STA1) strains, such as those used to ferment saison, and are only used when trying to achieve an extremely dry finish. Another way to get an ultra dry beer would be to pitch enzymes (e.g., amyloglucosidase) in addition to yeast.
Flocculation
Flocculation refers to how well yeast cells clump together and settle out of the finished beer. High-flocculating yeasts lead to clear beer, while low-flocculating yeasts stay in suspension longer, ideal for hazy styles like New England IPAs.
Temperature
The listed temperature is the ideal range the yeast should be fermented. We’ve already covered the impact of fermenting at one end of this range from the other.
Viability and Cell Count
Yeast viability refers to the number of live yeast cells available for fermentation. This number is indicative of new yeast when it is packed, so keep in mind that older yeast packets may have lower viability. A proper pitch rate ensures healthy fermentation. Yeast calculators, like those from Brewfather or BeerSmith, can help homebrewers determine the correct number of cells needed for their batch. We’ll dig more into pitch rates later.
STA1
Some yeast manufacturers list whether a yeast strain is Saccharomyces cerevisiae var. diastaticus (containing the STA1 gene). These strains are capable of fermenting residual carbohydrates that are unfermentable to most Saccharomyces strains.
Pitching Enough Yeast
Getting the right pitch rate is essential for a successful fermentation, and it depends on factors such as wort gravity, beer style, and fermentation temperature. Underpitching can lead to stressed yeast, sluggish fermentation, and excessive ester or diacetyl production. Overpitching, while less risky, can sometimes result in fewer flavor compounds or an overly clean beer that lacks character. That said, there is no hard and fast “ideal” pitch rate. Fermentations can successfully ferment over a range of pitch rates, but different pitch rates can, and often do, influence beer flavor. Some brewers prefer using low pitch rates for weizen yeast and others prefer higher pitch rates. Trialling different rates and learning from the results to determine your preferences is worthwhile. Don’t forget to take notes as you test!
The standard pitch rate guidelines vary depending on the author or manufacturer, but we generally land on these numbers when using liquid yeast:
Ale Fermentation: 0.75 million cells per milliliter per degree Plato
Lager Fermentation: 1.5 million cells per milliliter per degree Plato
To calculate the number of yeast cells needed for a 5-gallon (19-L) batch of wort, use this formula:
Cells needed = wort volume (in gallons) × wort strength in ˚Plato × pitch rate × 3,785 (mL in a gallon)
As an example, for a 12.5 ˚Plato ale: 5 × 12.5 × 750,000 × 3,785 = 177 billion cells.
A fresh liquid yeast pack typically contains around 100 billion cells, meaning that a standard ale at 1.050 would require about one pack with a yeast starter or two packs without a starter to ensure a proper pitch. A lager would likely need two to three packs or a large yeast starter to reach the necessary cell count. Imperial Yeast is one manufacturer that has a broad range of options and their liquid yeast comes in 200 billion cell pitches. Personally, I love that because I know I just need one pouch for a 5-gallon (19-L) batch, and second, if a pouch sits in my fridge for several months I can still safely pitch it because it started with more cells than I needed.
Dry yeast packets (11.5 g) generally contain 100-115 billion cells and are a convenient option for single-pitching standard gravity ales. However, for higher-gravity beers (above 1.060), additional packs are recommended to avoid fermentation stress.
Online pitch rate calculators simplify this process by allowing brewers to enter their wort gravity and yeast viability to get precise yeast pitching recommendations.
Troubleshooting Common Yeast Issues
Stuck Fermentation: Could be due to underpitching, low fermentation temperature, or poor yeast health. Solutions include raising the temperature or pitching fresh yeast.
Off-Flavors: Acetaldehyde (green apple) or diacetyl (buttery) off-flavors may result from stressed yeast or improper fermentation temperatures.
Think of brewing as starting a rock band. You, the brewer, are the manager, setting the stage and getting all the equipment (malt, hops, water) ready. But the real star of the show — the one who determines the style, energy, and final sound of your beer — is the lead singer. That’s your yeast.
Do you want a smooth, clean performance? Pick a yeast like US-05 or WLP001, the brewing equivalent of a classic rock singer – reliable, crisp, and won’t subject your wort to too many surprises.
Looking for some personality and flair? A British ale yeast like Omega’s OYL-011 is your Mick Jagger, adding fruity esters and making your beer a little more dynamic.
Going for high-energy and big flavors? A Belgian yeast strain will bring the stage presence of Freddie Mercury — bold, expressive, and impossible to ignore.
Need something technical and precise? Lager yeast is like a classically trained opera singer, slow and steady but delivering a refined, clean performance when given the right environment (cold fermentation).
Now, if you don’t give your singer the right setup — good stage conditions (proper fermentation temperature), enough oxygen (healthy yeast handling), and the right-sized crowd (proper pitch rate) — they’re going to struggle, forget the lyrics, and maybe even storm off stage (stuck fermentation). But if you set them up for success, they’ll deliver a flawless performance, and the crowd (your taste buds) will go wild.
So, when picking your yeast, don’t just grab the first one you see — think about the kind of beer you want to make and pick the right front man for the job. Rock on with your yeast selection, brewers!
