Nateo

Recipes 

I suspect it has something to do with the H+ ions interfering with proton ATPase and secondary active transport, but I'm not sure.

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To paraphrase Dr. England - "Off-flavors smooth with time. So do mountains. Brew it right from the start!"

My blogsite: http://nateobrew.blogspot.com/

ajdelange

Recipes 

Yeast are quite acidophillic. This is how they compete with bacteria i.e. by establishing a low pH in the wort. The corresponding pH drop can be used as an indicator that the fermentation is well underway.

Yeast are not damaged by washing down to pH 2. Beyond that is not so good for them. Exactly which enzymes it is that are denatured I do not know but it is doubtless denaturing of enzymes that does the harm.

Nateo

Recipes 

When you're acid-washing yeast, the yeast isn't transporting anything through the cell walls, right? The low pH would make it go dormant? Under normal circumstances, the yeast is able to maintain an internal pH that keeps the enzymes from being denatured at 2 pH, but under 2 something happens to change that?

__________________
To paraphrase Dr. England - "Off-flavors smooth with time. So do mountains. Brew it right from the start!"

My blogsite: http://nateobrew.blogspot.com/