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Mash Temp

Discussion in 'Homebrewing' started by Boonedog, Oct 29, 2013.

  1. Boonedog

    Boonedog Savant (250) Illinois Apr 10, 2013

    So. I was brewing my first AG IPA Saturday. It was in the 40's outside but sunny. With my first AG batch (this is my second) I had a bit of trouble keeping my temp in my cooler steady over a full 60 minute rest so I added spray foam to the lid. Anyway I was looking for a rest of 151. I ended up about 154 after doughing in. Since it was chilly and I had issues before I figured I would leave it and let the temp drop. Well I guess the foam in the lid did the trick because my temp only dropped to 152 after 60 min.

    How will this change my beer if at all?
  2. premierpro

    premierpro Savant (385) Michigan Mar 21, 2009

    Not a lot. I mash most of my ales between 152-154. Take care.
    azorie likes this.
  3. VikeMan

    VikeMan Poobah (1,030) Pennsylvania Jul 12, 2009 Beer Trader

    All other things being equal, you'll get a slightly less fermentable wort, leaving a slightly higher FG, sweetness, and mouthfeel.
    azorie likes this.
  4. Not enough to worry about.

    While I have no reference sources to back this up, experience has led me to conclude that, in a declining temperature scenario like this, the wort is approximately as fermentable as it would have been had you held it at the lowest temp you observed. Obviously the starting temp can be a factor (you won't have much luck starting at 180 and letting it drop to 148, for example), but 154 to 152 is, for all practical purpose, like 152 for the duration. This is actually a very handy technique if you have trouble hitting your mash temp. Simply err on the part of a bit high and let it drop to your target.

    FYI, I simply lay potholders on top of the uninsulated lid. At room temp, the temp drops about 6 degrees over nine hours.
    billandsuz likes this.
  5. Applecrew135

    Applecrew135 Aficionado (205) Pennsylvania Jul 18, 2012 Verified

    Useful information... I had the same thing happen this weekend. I was shooting for 148, but was at 154 after dough in (I stupidly left the stove top on while mashing in). I grabbed a small handful of ice and got the mash down to 149 in about 20 minutes. After 90 minutes the temp was 147. Hopefully I'll get the fermentability I was shooting for.

    I guess I shouldn't obsess too much... it's fermenting away right now with a really nice, thick creamy kraeusen... actually the nicest kraeusen I've seen on any of my beers since I went all grain.
  6. VikeMan

    VikeMan Poobah (1,030) Pennsylvania Jul 12, 2009 Beer Trader

    It sounds like you were shooting for 148F (a pretty low temp) to maximize fermentability. You might be interested to know that there is data to show that for single infusion mashes, at least under the test conditions used, you get maximum fermentability at about 151F (Kai Troester data) or 152F (Greg Doss data). Those were the sweet spots...higher and lower temps resulted in less fermentability.

    Their data does go against the fairly commonly held belief that lower temp = more fermentability. Personally, I think that belief stems from the fact that very low mash temps are common with certain styles, like some Belgians, which also happen to (often) use highly attenuative yeast strains and simple sugar additions, both of which increase attenuation (aside from the mash's contribution to fermentability).
  7. Boonedog

    Boonedog Savant (250) Illinois Apr 10, 2013

    I was shooting for 151 actually. Still an AG noob figuring out my system
  8. mattbk

    mattbk Savant (435) New York Dec 12, 2011

    FYI - easy fix if you mash too high (say, 154 vs 151) - add a bit of cold water to the mash at the beginning. It won't take much and won't affect your batch really at all. Mashing low is a tougher problem to have, especially if you mash in a cooler - which is why I usually aim a little high then adjust down with cold water.
  9. Boonedog

    Boonedog Savant (250) Illinois Apr 10, 2013

    I thought about doing that but like i said in my original post I previously had lost quite a bit of temp over the 60 minute rest. Now I know I can hold temp better I will do that next time.