I recently bought an amber ale/lager kit. The yeast that came with the kit behaves like a lager yeast when used from 52 to 62 degrees and like an ale yeast from above 64 to 74 degrees. So I went with the ale temps but I kept it at 64 for the first day and a half. Then Monday came and I went to work and the house temp went down to 55 during the day. The beer temp dropped to 63. That got me to wondering, what would happen if I had allowed the first day to proceed at the ale temp around 67 degrees and then dropped the temp to the 57 degree range? Would the yeast have a problem starting out one way and then transitioning? Sounds like I need a 3 batch experiment. Any thoughts?
They probably wouldn’t like that temp swing much.
Dropping the temperature near the end of fermentation would most likely cause the yeast to become lazy and give you a stuck fermentation. You would be better off starting at 55F and letting it rise slowly to 65F in order to ensure complete attenuation.
Got it. I have been pretty steady between 63 an 65 so I think I am OK. Right now is near hour 54 since the bubbling started and I am still bubbling so I think all is going well.
Heavy temp swings in any direction makes for disgruntled yeast and may result in off flavors or stalled ferments. As others stated above, you’re better off raising slowly towards the end of the ferment than lowering. My SOP is keeping it around 64ish for the first four days then raise it a degree a day till its at 67-68. Then after that temp swings are not nearly as detrimental so I just leave it at room temp.
That said, I’ve never worked with the yeast in question here so I can’t really speak for the performance at these different temps.
You might have some diacetyl too, so be aware of that. That can happen when the temp changes a lot. Make sure to give it a few days to a week in the mid 60’s near the end of fermentation.
