August 11, 2025 inside escarpment, knowledge Richard Preiss

Isar Lager Under the Microscope: What 28 Breweries Taught Us

At Escarpment Labs, we're proud of the performance and flavour profile of our Isar Lager yeast, a strain selected for its ability to deliver clean, balanced lagers with reliable fermentation characteristics.

Isar is our “house lager” strain of choice, because it consistently delivers neutral flavours (lower acetaldehyde and ester formation than 34/70 variants, at the expense of slightly slower fermentations).

But like all things in brewing, the lager fermentation process isn't one-size-fits-all. Last year, some brewers reached out to our team with feedback: while Isar Lager generally performed well, certain brews showed longer-than-expected lag times and slow fermentations.

As a lab committed to data-driven support and continuous improvement, we took this as a valuable opportunity to learn. Specifically, we wanted to investigate:

Are there patterns among brewers reporting longer fermentations?
Could malt type, fermentation temperature, or nutrient strategy be driving the variability?
Are there actionable best practices we can recommend to improve Isar Lager fermentation outcomes?

To answer these questions, we surveyed brewers who had recently used Isar Lager. We collected and cleaned responses from 28 breweries, covering a range of beer styles, process setups, and fermentation timelines.

Isar Lager vs 34/70: Key Differences

We often get asked how Isar Lager compares to the global workhorse 34/70. Here's a side-by-side comparison to help brewers choose the right tool for the job:

Feature	Isar Lager	34/70 (global variants)
Flavour Profile	Clean and malt-accented, low sulfur, low diacetyl	Very clean, slightly estery, elevated S02, may require diacetyl rest
Ester Production	Lower	Moderate
Acetaldehyde	Low	Slightly higher
Fermentation Speed (cold)	Slightly slower	Faster
Diacetyl Rest Requirement	Usually minimal	Often required
Flocculation	Medium	Medium to High
Attenuation	80-83%	80-84%
Ideal Fermentation Temp	10-15°C	9-13°C Cold-adapted variants can ferment lower

Why we offer Isar Lager as our top lager strain: It delivers on our core goals of balance, reliability, and flavour neutrality in lager beers. While it may be slightly slower to reach FG at colder temperatures than 34/70, it rewards brewers with crisp and clean results.

Key Findings from the Customer Survey

1. Nutrient Use Matters with Lager Fermentation Timeline

We categorized nutrient additions into three buckets: None, Yeast Lightning (Escarpment's proprietary blend), and Other.

Nutrient Group	Count	Avg Time to FG	Std. Dev
Yeast Lightning	11	8.7 Days	±2.7
Other Nutrients	10	10.1 Days	±2.9
None	7	10.9 Days	±4.0

Takeaway:

Using Yeast Lightning shaved ~2 days off fermentation compared to no nutrient use. Other nutrients were helpful, but slightly less consistent. Brewers fermenting cooler or using European base malts should strongly consider nutrient supplementation.

2. Malt Type Impacts Fermentation Rate of Isar Lager

We observed some variation in fermentation time by base malt type:

Domestic pilsner and North American 2-row malts trended toward faster fermentations.
Some European pilsner malts, especially in combination with cooler fermentation regimes, were associated with longer time to final gravity.

Takeaway:

This supports the initial hypothesis. European base malts may interact differently with Isar Lager, possibly due to FAN levels or beta-glucan content. In general, European base malts are lower in FAN, and may be less modified (meaning a higher beta glucan level). Traditional mashing practices such as decoction can help liberate extra FAN when using European pilsner malts.

3. Pitch and Fermentation Temperature Impacts on Lager Yeast

Correlation analysis showed:

Higher fermentation temperature slightly decreased time to FG (r = -0.21)
Higher pitch temperature was weakly associated with slower fermentation (r = +0.23)
- This is an interesting finding. One possible explanation is that yeast forms their membranes in response to the temperature they sense, so shifting yeast from a warm temperature to a cold temperature could have an impact on fermentation rate for some strains. This is purely hypothetical and should be tested!

Takeaway:

Brewers pushing lower temperatures (e.g. 9-10°C) saw slower fermentation. If fermenting below 11°C, consider increasing the pitch rate and oxygenation, and use a nutrient.

4. Mash Type Impact on Fermentation Time

Mash Type	Count	Avg Time to FG	Std. Dev
Single Infusion	21	9.6 Days	±3.4
Step Mash	5	9.9 Days	±2.7
Decoction	2	10.8 Days	±3.2

Takeaway:

There was a slight trend toward longer fermentations in decoction mash beers, which often overlap with the use of European malts (a confounding variable). Mash method may be a compounding factor, but it isn't a primary driver.

5. Propagation and Pitch Rate Impacts on Fermentation Time

Propagation	Count	Avg Time to FG	Std. Dev
Yes	3	12.5 Days	±2.2
No	25	9.4 Days	±3.2

Propagation resulted in 3 days longer time to FG.

Pitch rate correlation with Time to FG: r = -0.21, indicating a mild decrease in fermentation time with a higher pitch rate. However, this effect was smaller than we expected.

Takeaway:

Yeast propagated by brewers showed slower performance, possibly due to suboptimal conditions or lower vitality. Brewers propagating in-house should ensure good aeration and nutrition during propagation.Pitch rate may not matter as much as ensuring the yeast is healthy (high vitality). There is more to come on pitch rate impact with lager yeast strains!

6. Longer Storage Time Between Batches = Longer Fermentations

There was a positive correlation between yeast storage time and time to FG (r = +0.26). This means that the longer the brewer stores the yeast on average, the longer the time to FG. Additionally, two brewers who did not use nutrients reported having challenges with repitching Isar when stored for over 2 weeks, while several others using Yeast Lightning reported (shockingly!) storage times of up to 40 days with success.

Takeaway: While Isar Lager holds viability well, long storage or inconsistent nutrition could impact fermentation performance, especially in repitches.

7. Dissolved Oxygen: You Can’t Control What You Don’t Measure

DO Measured	Count	Avg Time to FG	Std. Dev
No	21	10.0 Days	±3.0
Yes	7	8.9 Days	±3.9

Takeaway: Brewers who measured and controlled dissolved oxygen (DO) achieved faster fermentations on average. While this could reflect better process control overall, it also reinforces the importance of oxygenation and in controlling DO in lager fermentations. Wort level DO meters are affordable and can improve your brewery’s efficiency!

Recommendations for Optimal Isar Lager Fermentations

Based on the data, here are our recommended best practices:

1. Use Yeast Lightning Nutrient

Especially when fermenting cold or using European malts.

2. Pitch at 10-12°C and ferment at 11 to 13°C for a balance between flavour and performance.

Warm pitching is not correlated with faster fermentations, in this data set.

3. Measure dissolved oxygen with a meter and target 10-15 ppm for consistent results.

4. Avoid long-term storage before repitching (less than 2 weeks)

Keep yeast cold and fresh.

5. If propagating, use high-quality wort, oxygenation, and consider supplementing nutrients.

6. Increase pitch rate for cold fermentations (<11°C).

Final Thoughts & Ongoing Support

This project demonstrates the benefits of collaborative problem-solving and information sharing between Escarpment and our brewery partners. Thanks to the customers who shared their process data, we’ve gained actionable insight to improve the reliability of Isar Lager and provide optimal advice.

As a bonus to make this strain as easy as possible to work with, we’ve improved our propagation nutrient regime for Isar and our other lager strains, based on a 2-year-long project investigating lager yeast nutrition and propagation improvements. More on that to come!

If you’re seeing long lag or slow fermentations with Isar or any other Lager strains, don’t hesitate to reach out to our technical team. We’re here to help.