Pressure Ferment a-09

williamneal

Hello,
I am making a Great Lakes Christmas Ale clone using A-09 yeast. I have a Fermzilla and had the pressure set to about 7psi. I read in another forum that Ales yeast should not be pressure fermented as it will suppress the esters wanted in an ale.. My OG was 1.065 and after 48 hours it is at 1.020. I let the pressure out of the fermenter and am hoping for another 5 or so points of gravity drop. Is it too late to get any ester production?

Miraculix

Yes.

VikeMan

If you mean an increase in ester production comparable to what you would have got if you hadn't pressurized initially, yeah, it's too late. But you already have some esters (despite pressurizing), and are probably still getting some esters made even with your 5 points or so to go.
The common mantra is that ester production happens very early in fermentation, but this isn't quite true, strictly speaking. But from a practical standpoint, it may as well be true. What does happen very early in fermentation is fusel alcohol production. Later on, most of the fusels are converted (by the yeast) into esters. So it's more accurate to say that the parameters for ester production are set early on.