Troubleshooting - Slow Kettle Sours
Root causes of slow or stalled kettle/quick sours
- Temperature too high. The optimal temperature for most Lactobacillus strains used in brewing is 37ºC.
- Too much oxygen/air can slow down certain strains like Lactobacillus plantarum.
- Souring in a kettle and using the jackets/elements to maintain temp is risky - Lacto settles and may overheat in hot spots.
- Lacto ferments can stratify, e.g. different pH in different parts of the tank. We suggest rousing to get a representative sample.
- Residual IBU/hop material from a previous brew in the kettle, whirlpool, or heat exchanger can cause minor carryover of bacteria-inhibiting compounds, causing slow or incomplete souring by hop sensitive Lacto strains.
- Temperature too high. The optimal temperature for most Lactobacillus strains used in brewing is 37ºC.
- Too much oxygen/air can slow down certain strains like Lactobacillus plantarum.
- Souring in a kettle and using the jackets/elements to maintain temp is risky - Lacto settles and may overheat in hot spots.
- Lacto ferments can stratify, e.g. different pH in different parts of the tank. We suggest rousing to get a representative sample.
- Residual IBU/hop material from a previous brew in the kettle, whirlpool, or heat exchanger can cause minor carryover of bacteria-inhibiting compounds, causing slow or incomplete souring by hop sensitive Lacto strains.
Questions that will help us help you:
1. What is the souring/pitch temperature?
2. Do you purge with CO2?
3. What vessel do you sour in?
4. Do you recirculate/rouse the ferment?
5. Was the brewhouse CIP'd prior to the unhopped wort brew?
6. Do you notice any off flavours? Could you describe it?
7. Did you rouse/mix the tank prior to sampling to get a representative sample?
Additional Resources
Lactobacillus 101 on YouTube
The Road to Lacto 2.0 on YouTube
2. Do you purge with CO2?
3. What vessel do you sour in?
4. Do you recirculate/rouse the ferment?
5. Was the brewhouse CIP'd prior to the unhopped wort brew?
6. Do you notice any off flavours? Could you describe it?
7. Did you rouse/mix the tank prior to sampling to get a representative sample?
Additional Resources
Lactobacillus 101 on YouTube