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Thread: Mash temperature and efficiency

  1. #1
    Join Date
    May 2011
    Posts
    51

    Mash temperature and efficiency

    I've been noticing my efficiencies are a lot lower over the last couple years. At first I thought it was my MLT: I had built one with a cooler and a toilet line, and I figured I just crushed the toilet line. I upgraded the MLT to a Bazooka, but the efficiency stayed pretty low (around 70%). Today, for the first time in a couple years, I skipped the MLT and did a BIAB. Before I built my MLT, I was typically hovering around 8085% efficiency with BIAB, so I was excited to calculate my efficiency. Once again, 70%.

    So apparently it wasn't the toilet supply line in my MLT, nor was it my typical regimen if double- and triple-decoction mashes (single infusion today), nor was it the MLT itself.

    The only other thing I can think of that's changed since I first started seeing low efficiencies is that I started mashing really cool. Today's brew I mashed at 147F, which is pretty typical for me. When I do decoctions, I typically do something like 122F140F158F. Sometimes I'll skip the protein rest and just do 140F158F. Sometimes I mash out, sometimes I don't; but I always batch sparge. Honestly, I don't understand what a mash-out buys me if I'm just going to batch sparge, but that's a whole other topic.

    I recognize that batch sparging isn't the most efficient, but it's not like that changed. I was batch sparging when I was getting better efficiencies.

    So... has anyone heard of getting lower efficiencies at a lower mash temperature? Am I totally out to lunch on this?

    The last thing I can think of is that I've pretty much exclusively been using Pilsner as my base malt over the last couple years. But I have trouble believing that's the issue.

    Just to be clear: this isn't a big deal. I'm not that concerned with efficiency, my beers are tasting great and I'm having fun brewing. But it's got me wondering what's different between then and now.

  2. #2
    Join Date
    Sep 2007
    Posts
    1,983
    Maybe your thermometer is a little off? If it dips much below 145 conversion gets pretty difficult. Since I don't use a recirculation system (and it sounds like you don't either) your bound to have some cool spots.
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  3. #3
    Maybe, over time, the gap on your (or your LHBS's) mill has gradually increased the slightest amount and so you now have less flour in your grist?
    -B'Dawg

    Give a man a beer and he'll waste an hour. Teach him to brew and he'll waste a lifetime. - Nuco Gordo

  4. #4
    Join Date
    May 2011
    Posts
    51
    Those are both worth pondering. Thanks for the tips!

    I can probably "fix" the thermometer easily enough by calibrating it in ice water and boiling water. That might be the first thing to check.

    Again, I'm liking the beer that's resulting, so this isn't a big problem... it's just been making me scratch my head on brew days.

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