Best Practices - Yeast Propagation
How to Propagate Yeast for Your Brewery
Brewing yeast propagation is a complex task that requires attention to detail and consistency.
Done right, it can save money and open up the ability to use a wider range of yeasts.
Done poorly, it can hamper production schedules, lead to frustrating flavour variability, and even lead to dumped batches of beer.
Here's a guide to help you get started with yeast propagation for optimal brewing results.
1. Understanding Yeast Propagation
Brewing yeast requires the right conditions to thrive. Here are some key fundamentals:
- Nutrients Needed: Yeast needs malt sugars, complex nitrogen, and pH buffers.
- Optimal Medium: Use wort at 10–15ºP with at least 200ppm free amino nitrogen (FAN). If you're using malt extract, supplement with yeast nutrients like Escarpment Labs' Yeast Lightning for best results.
2. Preparing Yeast Propagation Wort
Follow these steps for creating a suitable wort:
Target Parameters:
- Wort gravity: 10–15ºP.
- FAN level: At least 200ppm.
Supplement Nutrients:
- Add Yeast Lightning at 20–40g per 100L (1 oz/28g per hL or barrel of wort)
Maintain Proper Sanitation:
- Use aseptic practices to avoid contamination.
Pro Tip: Different yeasts require different types and amounts of micronutrients (vitamins, minerals, etc). Using a complete nutrient solution such as Yeast Lightning Nutrient can provide insurance against yeast running out of important food.
3. Aeration During Propagation
Proper oxygenation is essential for yeast health and to ensure the most effective yeast cell multiplication:
- Recommended Method: Use sterile, filtered compressed air for continuous aeration.
- Avoid Waste: Pure oxygen is effective but can be wasteful if used continuously. It's better suited for fermentation rather than propagation.
Pro Tip: Using pure oxygen at the start without continuous dosing will result in a more standard fermentation process, and will limit you from generating a high cell density.
4. Propagation Parameters
- Cell Growth Expectations: For wort-based propagation, you can achieve 100–200 million cells/mL.
- Batch Sizing: For example, to propagate enough yeast for a 20 hL batch, you may need a 5 hL propagator, depending on the yeast strain.
Pro Tip: We strongly encourage using a microscope and hemocytometer to count your cells after propagation. If you do not count the yeast cells, you may introduce a large amount of variability into your brewery process.
5. Propagation Temperature
Choose the right propagation temperature based on yeast type:
- Most Strains: 20–30ºC.
- Lager Yeast: Propagate at the lower end of this range (~20ºC).
- Kveik Yeast: Use the higher end (30ºC).
Pro Tip: You can propagate hotter than you ferment without adverse effects.
6. Starter Culture Requirements
Seed your propagator with the correct volume of yeast:
- Inoculate a 1–2 hL pitch of liquid yeast into every 1 hL of propagation wort.
- For strains like lager or English ale, use a 2 hL pitch per 1 hL of propagation wort for optimal growth.
Pro Tip: We suggest purchasing fresh direct yeast pitches rather than using multiple homebrew packs. Homebrew packs have a longer shelf life than direct pitches and may show more variable results in brewery propagation.
7. Risks and Precautions
Propagating yeast in-house comes with potential risks:
- Contamination: Improper sanitation can lead to off-flavors or spoilage.
- Financial Costs: The opportunity cost of losing a tank of beer due to propagation issues can outweigh the cost of purchasing ready-to-use yeast.
- Expert Support: Consult Escarpment Labs for guidance on establishing a robust in-house propagation program.
8. Ensuring Yeast Purity
Regularly test for contamination using specific agars:
- Recommended Media: WLN (wild yeast detection), LCSM (lactic acid bacteria), MRS (spoilage bacteria).
Perform regular quality control checks to avoid cross-contamination and ensure your propagated yeast maintains purity.
9. Escarpment Labs Consultation
If you need assistance or have concerns about yeast propagation, Escarpment Labs offers consulting services to breweries. Contact us for expert advice tailored to your brewery’s needs.