rodwha said:
eric: Do you mash high with all dark beers? Do you mash at a more typical temp for a period and the mash out high? If so why?
Going over this conversation is starting to get confusing. Mash temps always get me because I have just started paying attention to the amylase's. We seem to have a good number of experienced people in this thread that weren't here when I initially responded. I'll go over my notes and y'all see if what I'm saying makes sense. My numbers are straight, but given what other people in HBT and the Internet in general are saying, I might be applying it incorrectly. The way I understand it:
Alpha amylase works at 148-165 and will convert starches better. It is capable of breaking down amylose chains and amylopectin very efficiently from the ends or the middle of the chains to produce a lot of fermentable sugars for the yeast to eat. This results in less thick beers, that have less residual sweetness and more alcohol.
Beta amylase works best at lower temps: 130-155, and will denature above 160. Beta will break down amylose chains starting only at the tips, meaning that it takes longer, and will not breakdown amylopectin very well, creating sugars that the yeast cannot digest. This results in thicker mouthfeel, less alcohol, and residual sweetness.
Letting both work in tandem (150-155) is what most people advocate. I prefer to isolate one or the other.
I do heavy stouts at high temps 155-165 because I'm not concerned about residual sugars increasing the mouthfeel because of the massive malt bill.
My DIPA and Belgian light beers are done at lower temps (138-143) to allow the leftover sweetness accentuate the hops and fruity esters; the malt bill being so light, I'm not concerned about too much mouthfeel.
I haven't done step mashes because I haven't had a good system to easily change temperatures in my beer. I now have a RIMS system that will let me change temps easily, but noting my confusion over mash temps and their effect on the outcome, I need to bone up before I start playing with it. I always mash out at 172. It's high enough to cease amylase activity (though I'm not sure why this is necessary if we're about to boil it), but not high enough to significantly increase tannin removal from the grain. Over 180, I understand, is too high.
I've reversed positions a couple times, but this is exactly what my brewing notes are. I could use some feedback in what I've messed up and hopefully, my confusion will help the OP and some other newbie brewers learn something too.
I welcome corrections to my numbers, assumptions, or brewing processes, though. I'm not confident enough to back these up with any more data than I have put above. I'm not trained in brewing and learned everything through Wikipedia. So far this has worked for me, but I'm always looking to learn from more experienced brewers particularly about mash temps.