I have spent the last little bit searching the forums and have not really found an answer to this question. I have a cream ale (OG 1.045, not sure of FG yet) that will be done and going into bottles next Sunday. I am going to brew another cream ale that day and thought I would experiment and try to reuse the yeast. I am NOT pitching straight onto the cake--just harvesting whatever Mr. Malty tells me to and then using it in the next batch immediately that same day. So--my question is: do I still have to aerate the wort or is this unnecessary since the yeast have already reproduced? I didn't know if oxidation would be an issue since I was reusing already reproduced yeast. Thanks in advance for the info!!
Aerating reused yeast
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I agree, as I have heard part of the flavour profile comes from the byproducts formed when the yeast are reproducing.
Thanks a lot for the info--that sure clears things up.
I was wondering however--once fermentation has begun, why do yeast produce off flavors when additional oxygen is added to the wort and why does this same mechanism not produce off flavors when you reuse yeast.
Once again--that is not me questioning your advice--you answered my question perfectly. I just like to know the scientific reasons behind why things happen or don't happen.
I was wondering however--once fermentation has begun, why do yeast produce off flavors when additional oxygen is added to the wort and why does this same mechanism not produce off flavors when you reuse yeast.
Once again--that is not me questioning your advice--you answered my question perfectly. I just like to know the scientific reasons behind why things happen or don't happen.
The oxygen is required for the yeast to reproduce as multiply in a basic simple explanation and this is all done aerobically. Once the growth phase is complete and the yeast begin fermenting things basically go anaerobic and oxygen is no longer needed or desired.
A great book about yeast I would highly recommend is called "Yeast" by Chris White and Jamil Zanisheiff. It really delves into the biology and science of it all in very easy terms!
A great book about yeast I would highly recommend is called "Yeast" by Chris White and Jamil Zanisheiff. It really delves into the biology and science of it all in very easy terms!
I agree with duboman. 'Yeast' is fantastic. I finished reading/studying it last week.
Probably the best way to think about repitching a slurry is that you are not continuing the past fermentation, you are starting a new one. You are just pitching the correct amount of yeast from a slurry rather than from a pouch or a starter. So, do everything you normally would- feed it, oxygenate it, pitch at proper temperature. Treat your yeast with the respect it deserves and it will do you good.
Probably the best way to think about repitching a slurry is that you are not continuing the past fermentation, you are starting a new one. You are just pitching the correct amount of yeast from a slurry rather than from a pouch or a starter. So, do everything you normally would- feed it, oxygenate it, pitch at proper temperature. Treat your yeast with the respect it deserves and it will do you good.
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