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Why do you have to cool wort to add yeast?
- Thread starter h4brewing
- Start date
brewfun
Grandmaster Brewer
Rehydrating yeast is different than giving it an optimal environment. Plus, chilling wort is not just about yeast.
We chill wort to create cold break, which has these benefits:
Eliminates chill haze
Enhance head retention
Increase O2 absorption for yeast growth
Provides a nutrient for yeast
Preserves aromatics
Preserves hop bitterness
Cooler wort also helps reduce diacetyl production and eliminate the reformation of DMS. Recently, I learned that yeast have a hard time reducing diacetyl if they don't ever get back up to the temperature they were pitched. This is especially important for lagers and cold conditioned ales.
We chill wort to create cold break, which has these benefits:
Eliminates chill haze
Enhance head retention
Increase O2 absorption for yeast growth
Provides a nutrient for yeast
Preserves aromatics
Preserves hop bitterness
Cooler wort also helps reduce diacetyl production and eliminate the reformation of DMS. Recently, I learned that yeast have a hard time reducing diacetyl if they don't ever get back up to the temperature they were pitched. This is especially important for lagers and cold conditioned ales.
philm63
Grandmaster Brewer
What brewfun said; and...
The term "Pitching yeast" is interchangeable here. Let me start with the yeast first:
Yeast works within a set range of temperatures dependent on the strain. There are two forms used for brewing - dry and liquid.
Dry yeast can be re-hydrated prior to use, and this is often recommended. This is accomplished by placing the dry yeast in water at a specified temperature based on the instructions. Typically the water should be right around 100 F - much warmer (over 105 F) and the yeast may be damaged; much colder (below 85 F) and the yeast may not wake up properly - using the correct temperature is important here. Good sanitary practices are also very important here.
Sterile water should be used and this can be done by simply boiling the water first, letting it cool to the desired temperature, and then the yeast can be "pitched" into the warm water to wake it up and re-hydrate the cells. Some instructions tell you to wait 15 minutes or so for the yeast to re-hydrate. Cover the container with a piece of sanitized foil while re-hydrating.
The re-hydrated yeast is now ready to "pitched" into the cooled wort. But why do we need cooled wort?
The wort should be close to the desired fermentation temperature when pitching the yeast because if it is too warm, it may kill the yeast. Too cold and the yeast may not work at all - it'll just go to sleep and wait for the temperature to rise into its normal operating range.
The idea is to get the yeast active quickly to stave off any infectious critters and make for a healthy fermentation. This will happen only if the conditions are ideal. The correct range of temperatures for fermentation are determined in large part by the yeast manufacturer - if it is not clear on the packaging, a quick search in the Internet should give you what you need.
There is a lot of discussion that could take place on fermentation temperatures, but I'll not go into all that here. For now, suffice it to say you can pitch your dry yeast into warm water to re-hydrate it, and then pitch it into the cooled wort and let the fermentation begin!
The term "Pitching yeast" is interchangeable here. Let me start with the yeast first:
Yeast works within a set range of temperatures dependent on the strain. There are two forms used for brewing - dry and liquid.
Dry yeast can be re-hydrated prior to use, and this is often recommended. This is accomplished by placing the dry yeast in water at a specified temperature based on the instructions. Typically the water should be right around 100 F - much warmer (over 105 F) and the yeast may be damaged; much colder (below 85 F) and the yeast may not wake up properly - using the correct temperature is important here. Good sanitary practices are also very important here.
Sterile water should be used and this can be done by simply boiling the water first, letting it cool to the desired temperature, and then the yeast can be "pitched" into the warm water to wake it up and re-hydrate the cells. Some instructions tell you to wait 15 minutes or so for the yeast to re-hydrate. Cover the container with a piece of sanitized foil while re-hydrating.
The re-hydrated yeast is now ready to "pitched" into the cooled wort. But why do we need cooled wort?
The wort should be close to the desired fermentation temperature when pitching the yeast because if it is too warm, it may kill the yeast. Too cold and the yeast may not work at all - it'll just go to sleep and wait for the temperature to rise into its normal operating range.
The idea is to get the yeast active quickly to stave off any infectious critters and make for a healthy fermentation. This will happen only if the conditions are ideal. The correct range of temperatures for fermentation are determined in large part by the yeast manufacturer - if it is not clear on the packaging, a quick search in the Internet should give you what you need.
There is a lot of discussion that could take place on fermentation temperatures, but I'll not go into all that here. For now, suffice it to say you can pitch your dry yeast into warm water to re-hydrate it, and then pitch it into the cooled wort and let the fermentation begin!