Unlocking the World of Lager: Choosing the Right Yeast for Your Homebrew

The journey of Saccharomyces pastorianus

In the intricate world of brewing, where yeast is the unseen wizard behind the curtain, the origin of lager yeast, scientifically known as Saccharomyces pastorianus, has long been a captivating mystery. While the specific genesis remains elusive, one compelling theory takes us on a journey to the wild landscapes of Patagonia in South America. In the annals of brewing history, lager yeast has been synonymous with cool fermentation and the production of crisp, clean lager beer. The conventional wisdom was that this yeast was a result of human selection and hybridization in the beer-brewing centers of Europe. However, a paradigm-shifting theory surfaced in 2011 (research published in the journal PNAS), suggesting a more exotic origin.

Picture the windswept landscapes of Patagonia, where beech trees (Nothofagus) dot the region. Here, researchers proposed a captivating hypothesis: lager yeast, specifically Saccharomyces pastorianus, might have originated from a spontaneous hybridization event between a wild yeast called Saccharomyces eubayanus, thriving in the beech trees of Patagonia, and a traditional ale yeast.

This theory introduces a fascinating narrative of nature's role in shaping the yeast strains we use in our brewing endeavors. It suggests that, rather than a deliberate human selection in the cellars of European breweries, lager yeast's roots may trace back to a fortuitous union in the wild landscapes of South America. The proposed hybridization event in Patagonia opens a window into the interconnectedness of ecosystems and the intricate dance between yeast and their environments. If this theory holds true, it implies that the yeast strains we employ for crafting our favorite lagers carry a touch of the untamed, a genetic legacy from the rugged beauty of Patagonia.

For homebrewers delving into the art and science of brewing, understanding the potential South American origin of lager yeast adds a layer of appreciation to the brewing process. It underscores the dynamic interplay between natural elements and human ingenuity that has shaped the beverages we savor. As you embark on your brewing adventures, envision the yeast in your fermenter as a globetrotter, carrying a genetic passport with stamps from the beech trees of Patagonia. The mysterious origins of lager yeast remind us that brewing is not just a craft; it's a journey that spans continents, climates, and the vast tapestry of microbial life.

Now, armed with a newfound appreciation for the untamed origins of our brewing companion, let's seamlessly transition to the present-day saviors of our fermentations — the Fermentis SafLager yeasts.

The Essence of Lager Brewing

Lager beer, known for its clean, crisp, and refreshing characteristics, has captured the hearts of beer enthusiasts around the world. This classic style offers a wide spectrum of flavors, from the malt-forward Märzen to the hoppy Pilsner, making it a versatile choice for homebrewers. But the key to unlocking the full potential of lager brewing lies in selecting the right yeast strain. We’ll explore the world of lager and compare four popular lager yeast strains from Fermentis to help homebrewers choose the one that suits their brewing goals.

Lager is a beer style fermented and conditioned at low temperatures, typically between 44–55°F (7–13°C). This cold fermentation allows for the development of a clean and balanced flavor profile, which distinguishes lagers from ales. To create the perfect lager, the choice of yeast is paramount, as it significantly influences the final flavor and aroma of the beer.

Let’s explore the options Fermentis is offering to play with this style:

SafLager W-34/70: The Neutral Workhorse

SafLager W-34/70 stands out as a true workhorse among lager yeast strains, prized for its adaptability and reliable performance. Beyond its well-known characteristics of clean fermentation and balanced flavor profile, this yeast strain showcases its versatility by accommodating a broader temperature range, including fermentation at higher temperatures, up to 20°C (68°F). This expanded temperature tolerance allows homebrewers greater flexibility in their brewing practices, enabling the production of crisp and flavorful lagers even in warmer fermentation conditions. Whether crafting classic German-style Pilsners, American lagers, or experimenting with hybrid lager styles, SafLager W-34/70 continues to be a top choice for those seeking consistency and the ability to tailor lager characteristics to their preferences.

• Fermentation Temperature: Performs well in a broad range, but shines at 50–68°F (10–20°C).
• Flavor Profile: Produces clean and neutral flavors, allowing malt and hop characteristics to shine. Ideal for Pilsner, Helles, and more.
• Attenuation: Good attenuation without going too far in sugar consumption, resulting in a balanced, slightly malty beer.

SafLager S-23: The Crisp Contender

SafLager S-23 is a versatile choice suitable for a wide range of lager styles. It ferments clean and produces a crisp, well-balanced lager with a moderate level of sulfur compounds, typical for many traditional lager styles. SafLager S-23 is an excellent option for classic lagers like Pilsner, Helles, and Bock.

• Fermentation Temperature: Particularly suitable for cooler fermentation temperatures, around 53–60°F (12–15°C).
• Flavor Profile: Clean, crisp, and refreshing with slightly more esters and floral notes compared to W-34/70.
• Attenuation: Good attenuation, resulting in a drier finish.

SafLager S-189: The Malt Embracer and Hop Enhancer

SafLager S-189 is prized for its ability to enhance other raw material aromas, making it an excellent choice for hop-forward lager styles of the new world, or for malt-oriented styles of the old world. This yeast strain ferments with relatively low sulfur production, allowing hop character to shine or malty character to express its strength.

• Fermentation Temperature: Performs well in a range of 53–65°F (12–18°C).
• Flavor Profile: Enhances malt character and can boost hop aromas, making them more detectable in the final beer. Great for Märzen, Bock, New Zealand Pilsner, and India Pale Lager.
• Attenuation: Similar to W-34/70, producing balanced beers at an average dryness for lagers.

SafLager E-30: Your Ticket to “Asian-style” Lagers

Discover a new aromatic dimension of lagers with SafLager E-30, a yeast that helps craft more expressive, fruit-forward beers. It produces isoamyl acetate—the compound responsible for banana notes—at just above the sensory threshold, adding a subtle yet distinctive twist to your lager. Selected in Southeast Asia based on local market preferences and sensory analysis, this yeast is ideal for recreating popular lager styles from Vietnam, Thailand, Singapore, and Japan, including rice lagers. If you’re aiming to brew highly drinkable, light lagers that take your taste buds on a journey across the world, SafLager E-30 is a strong companion.

• Fermentation Temperature: Performs well between 53–65°F (12–18°C).
• Flavor Profile: Among Fermentis lager strains, this yeast produces the highest level of esters—particularly isoamyl acetate—bringing mild fruitiness while remaining within a classic lager profile. The ester concentration sits just above the sensory threshold (detectable by ~50% of tasters).
• Attenuation: Solid attenuation performance for clean, dry, and highly drinkable lagers.

SafBrew LD-20: The “Outside of the Box” Option for Dry Lagers

SafBrew LD-20 is the latest product to arrive in the world of Fermentis lager yeast for homebrewers. The particularity of this product is that you don’t only have a Saccharomyces pastorianus here; you also have an enzyme (glucoamylase) in the same sachet — it’s an All-In-One™ product. With this mix of active dry yeast and enzyme, you can reach the same alcohol level in your beer while reducing the original gravity up to 20%, resulting in a lower level of residual sugars and carbohydrates. Besides, you can count on it to achieve a high-performance fermentation in many different conditions with no defects and high apparent attenuation.

• Fermentation Temperature: Ferments well across a large range. You’ll achieve fermentation without problems between 54–68°F (12–20°C).
• Flavor Profile: An “outside of the box” product for experimenting with traditional lager styles. Its dry character makes it a strong candidate for session lagers and an interesting option for Cold IPAs.
• Attenuation: Designed for very high attenuation; expect about 98–102% apparent attenuation.

Choosing the Right Lager Yeast

When deciding on the yeast strain for your next lager brew, consider the following factors:

• Desired Beer Style: For clean and neutral lagers, SafLager W-34/70 is an excellent choice. For a crisp character with some esters, SafLager S-23 works well. For a malt-forward or hoppy lager that amplifies hop aromas, SafLager S-189 is the way to go. For a highly drinkable, dry lager, SafBrew™ LD-20 is a must.
• Fermentation Temperature: If you have precise temperature control, choose a strain that excels in your target range. If you can’t tightly control temperature or brew in a hot climate, consider strains that tolerate higher temperatures such as SafLager W-34/70 or SafBrew™ LD-20.

It may seem like a simple message, but the right lager yeast remains the one you like most in a specific recipe. At Fermentis, we do our best to help you make a good choice based on data, sensory analysis, and style expectations, but there is nothing better than experimentation because tastes vary. Liking something opposite to the standard expectations is part of what makes homebrewing a beautiful hobby: its diversity.

Let’s Lager!

In conclusion, the world of lager brewing is a delightful trip with numerous possibilities. Each yeast strain offers a distinct flavor profile, allowing you to craft the perfect lager to suit your taste, whether it's malt-forward or hop-forward. Consider experimenting with different strains to discover your favorite and tailor your lager to perfection. The next time you raise a glass of your meticulously brewed lager, take a moment to salute the yeast that might have started its journey in the enchanting landscapes of Patagonia, making its way to your brew kettle and leaving its mark on the refreshing elixir in your hands. Prost to the mysteries of lager yeast and the untold stories it brings to your homebrewing experience!

This article was researched, written, and provided to Northern Brewer Homebrew Supply by Fermentis.