Best Practices - Lager Fermentation

Why It Matters

Lager brewing demands precision. Even small mistakes in yeast handling, pitching, temperature, or oxygenation can slow down fermentation or impact flavour. Drawing from Escarpment Labs’ experience and aggregated brewery feedback, here is a guide to achieving clean, efficient, and reliable lager fermentations.

Best Practices For Lager Fermentations

1. Pitching Rate & Oxygenation

Pitching rate: Follow the rule of 1 million cells / mL / °Plato.
- For beers up to 12 °P, a standard pitch is sufficient
  - Escarpment Labs supplies lager yeast at 12 million cells /mL, which is equivalent to this pitch rate
- For higher gravities, adjust accordingly.
Oxygenation: Ensure wort has adequate dissolved oxygen (~10-15 ppm). This is especially critical for cold fermentations and higher-gravity brews.

2. Pitching Temperature & Fermentation Profile

Pitch 1 degree cooler than your fermentation setpoint (e.g. pitch at ~10 °C if your set temp is 11°C). This prevents yeast from battling your cooling system early on.
Once ~50% attenuation is achieved, you can raise the temperature slightly to encourage full attenuation and reduce diacetyl.
Do not crash the beer until a forced diacetyl test confirms it is clean.

3. Nutrients & Wort Quality

Nutrient supplementation can shorten fermentation time by 1-2 days.
If using European pilsner malts (lower FAN), consider a mash program that increases FAN availability (e.g. protein rests or decoction).
Yeast stored for more than two weeks tends to ferment sluggishly, keep storage time short and yeast healthy.

4. Managing Diacetyl

Always run a forced diacetyl test near the end of fermentation. Even clean strains can produce diacetyl under stress.
If needed, raise temperature gently for a diacetyl rest before cooling.

5. Oxidation & Transfers

Oxidation risk starts immediately after pitching - be vigilant.
Spunding valves: Use toward the end of fermentation to naturally carbonate, retain yeast aromatics, and reduce O₂ exposure.
For transfers, use CO₂/head pressure where possible. Pumps can be used, but watch for DO pickup.

6. Fermentation Temperature Control

Excessively cold fermentation (< 11 °C) often slows fermentation unnecessarily and may not produce "cleaner" results (strain dependent).
A sweet spot for many lager strains is 11-13 °C, with a controlled ramp up as fermentation progresses.
Avoid big swings in temperature.

7. Repitching Strategy

Aim to repitch yeast within 14 days for optimal vitality.
Monitor viability and vitality closely. Long storage or nutrient-starved yeast = sluggish fermentation.
For critical batches, prefer fresh yeast or recently cropped yeast.

Key Factors That Influence Lager Fermentation Performance

Factor	Influence on Fermentation	Best Practice / Mitigation
Yeast nutrition	Proper nutrient use often reduces fermentation time by ~2 days.	Always dose an appropriate yeast nutrient (such as Yeast Lightning Nutrient), especially when fermenting cold or using low-FAN malts.
Base malt / FAN level	Some base malts, especially European pilsner, provide lower FAN, slowing fermentation.	Use well-modified malts; consider protein rests or decoction for FAN release with undermodified malts.
Pitch temperature vs fermentation temperature	Warmer pitching does not guarantee faster fermentation; large pitch-to-fermentation temperature gaps can cause stress.	Pitch yeast close to fermentation setpoint (10-12 °C typically). Avoid large temperature swings.
Pitch rate / yeast vitality	Higher pitch rates can modestly improve speed, but yeast health matters more.	Ensure viability and vitality are high. Increase pitch rate slightly when fermenting cold.
Yeast storage / repitching	Yeast stored too long (over ~2 weeks) tends to ferment sluggishly.	Minimize storage time, store yeast cold, and maintain health with nutrients.
Dissolved oxygen (DO)	Oxygenated wort ferments more quickly and consistently than non-oxygenated wort.	Target ~10-15 ppm DO using pure oxygen with thorough mixing.
Mash regime	Decoction or under-modified malt schedules can extend fermentation slightly.	Use a mash regime suited to malt quality; infusion is sufficient for well-modified malts.
Temperature control	Colder fermentation slows kinetics; warmer risks off-flavors.	For most lager strains, ferment steadily at 11-13 °C. Fermentations at or under 10 °C are typically significantly slower and we only recommend ultra-cold fermentations for very traditional styles.

Lager Troubleshooting Quick Reference

Symptom	Likely Cause	Fix
Long lag phase	Low DO, low pitch rate, cold pitch	Increase oxygen, adjust pitch rate, pitch closer to target temp
Sluggish mid-fermentation	Low FAN or minerals, cold temperature, nutrient deficiency	Add nutrient, raise temp slightly, review base malt and nutrient
High diacetyl	Rushed cooling, yeast stress	Perform diacetyl rest, verify with forced diacetyl test
Oxidized flavors	O₂ pickup during transfers or packaging	Use spunding, CO₂ transfers, minimize agitation
Incomplete attenuation	Under-pitch, too cold, premature crash	Extend fermentation, warm slightly, confirm/test yeast vitality