Author Topic: Mash temps decrease from 158 to 150. Effect?  (Read 627 times)

Offline backpackerx

  • 1st Kit
  • *
  • Posts: 4
    • View Profile
Mash temps decrease from 158 to 150. Effect?
« on: January 03, 2018, 02:59:14 PM »
I BIAB and only do small 2 gallon batches. I mash in my boil kettle and with a typical grain bill using a 1.25L/lb ratio I'm mashing in 1.75 gallons or so. Since I just insulate my kettle with a towel I usually start around 158F and at the end of a longer 75 min mash I'm at 150 or even 148F sometimes.

My question is what sugars am I creating? I know higher temps create more unfermentables and mouthfeel and lower the opposite but am I getting a balance of both or do the longer chain sugars convert down as the mash cools?

I don't have a firm grasp of whether the wort profile stays somewhat fixed as conversion occurs or if say I'm at 150 for 20+ minutes toward the end am I converting almost everything to more simple sugars?

Thanks!

Offline Robert

  • Senior Brewmaster
  • ******
  • Posts: 1885
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #1 on: January 03, 2018, 03:34:37 PM »
You denature any enzyme above a certain temperature. Beta amylase is denatured staring around 144°F, but alpha amylase hits its peak activity around 158°F.  So if you start at 158°F, you will have eliminated the beta activity, it will not kick back in as the mash cools.  This will also reduce the ability of the alpha to convert starches, because it requires beta to "snip" some of the bonds it cannot before it can fully convert starches. So you are basically creating just the less fermentable sugars, but not very efficiently, leaving some unconverted starches.  To get full advantage of the enzymes in your mash, you either need to START at a lower temperature and then raise it (step mash,) or pick a compromise temperature around 153°F for the full duration.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline roger

  • Cellarman
  • **
  • Posts: 28
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #2 on: January 03, 2018, 04:19:44 PM »
In my experience, most homebrewers use a Igloo-type cooler for mashing. These are fairly inexpensive, especially in a 2 gallon size, and will keep the temperature within a degree or two for the entire mash, which is important to controlling the final product. Using the boil kettle with the temperature drop you are experiencing, you are still making beer. You gotta love this hobby, and there is something to the KISS principle.

There are several good threads on this forum showing how to modify the cooler by fabricating a false bottom or filter, with a drain valve to separate the wort from the spent grains. This is a simple method that works really well.
Cheers,

Roger

Offline dmtaylor

  • Official Poobah of No Life.
  • *
  • Posts: 3332
  • Two Rivers, WI
    • View Profile
    • Manty Malters - Meet the Malters! - Dave Taylor
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #3 on: January 03, 2018, 04:57:29 PM »
I do a similar thing as the OP, but 158 F start temperature seems too high for beta amylase to survive longer than a few minutes.  I start mine at more like 152-154 F and let it fall into the upper 140s and have been very pleased with the results from a 45-minute mash.  If I cared about attenuation like for a saison, I'd start even lower and mash longer, but for most styles this works very well.
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline backpackerx

  • 1st Kit
  • *
  • Posts: 4
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #4 on: January 03, 2018, 05:30:17 PM »
Thanks all. Looking back at my notes over the past 6 batches or so it appears the ones that mashed high have been the ones that didn’t attenuate too well. I’ll try for 153° or so next time and my kettle usually stays pretty consistent for the first 25-30 min so it sound like even if I drop to mid 140s by the end I should still be ok for beers where I’m not trying for higher FG or mouthfeel.

Offline Kevin

  • Cellarman
  • **
  • Posts: 54
  • Free from the Style Police!
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #5 on: January 03, 2018, 06:16:14 PM »
If you are doing BIAB and mashing in your boil kettle why not just add a little heat from the burner when needed to maintain your desired mash temp?
“He was a wise man who invented beer.”
- Plato

Offline backpackerx

  • 1st Kit
  • *
  • Posts: 4
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #6 on: January 03, 2018, 06:25:11 PM »
I did that once before and can do it again if needed but it was a bit of a pain to lift the bag off the bottom several times to prevent melting and hold it there for 2-3 minutes while raising the temp a few degrees. It's definitely doable and probably what I'll do again.

Offline Stevie

  • Official Poobah of No Life.
  • *
  • Posts: 6858
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #7 on: January 03, 2018, 06:31:54 PM »
I’ve had good luck putting the pot in the oven to hold temp. The oven light gives off some heat, but the insulation and still air is really what helps.

Offline Bob357

  • Brewer
  • ****
  • Posts: 258
  • I can't hang with Denny. My day ends at 1.060.
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #8 on: January 04, 2018, 12:12:56 AM »
I'm with Stevie. For a small batch I'd put it in the oven too. Not enough mass to maintain temperature at a normal room temp.
Beer is my bucket list,

Bob357
Fallon, NV

Offline backpackerx

  • 1st Kit
  • *
  • Posts: 4
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #9 on: January 04, 2018, 12:27:53 AM »
I’ve had good luck putting the pot in the oven to hold temp. The oven light gives off some heat, but the insulation and still air is really what helps.

Good idea.

Offline Robert

  • Senior Brewmaster
  • ******
  • Posts: 1885
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #10 on: January 04, 2018, 12:29:00 AM »
Stick inside a picnic cooler, or wrap it in a blanket --  endless ways to hold in heat!  But with that little thermal mass, you might want to check on it after 20-30 minutes until you establish how well your method works. 
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline hopfenundmalz

  • Global Moderator
  • I must live here
  • *****
  • Posts: 8926
  • Milford, MI
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #11 on: January 04, 2018, 12:50:56 AM »
Our oven’s lowest setting is 160F. I have preheated it, turned the oven off, mashed in a pot, placed pot of mash in oven, temperature doesn’t go up or down much. Easy Peasy.
Jeff Rankert
Ann Arbor Brewers Guild
AHA Governing Committee
BJCP National
Home-brewing, not just a hobby, it is a lifestyle!

Offline Robert

  • Senior Brewmaster
  • ******
  • Posts: 1885
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #12 on: January 04, 2018, 01:12:21 AM »
Our oven’s lowest setting is 160F. I have preheated it, turned the oven off, mashed in a pot, placed pot of mash in oven, temperature doesn’t go up or down much. Easy Peasy.
Caveat: calibrate or at least check your oven with a good thermometer. Oven thermostats are notoriously inaccurate and can vary greatly through their range.  You don't want to set your oven at 160°F only to put your mash inside a 250°F chamber!
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline hopfenundmalz

  • Global Moderator
  • I must live here
  • *****
  • Posts: 8926
  • Milford, MI
    • View Profile
Re: Mash temps decrease from 158 to 150. Effect?
« Reply #13 on: January 04, 2018, 02:34:37 AM »
Our oven’s lowest setting is 160F. I have preheated it, turned the oven off, mashed in a pot, placed pot of mash in oven, temperature doesn’t go up or down much. Easy Peasy.
Caveat: calibrate or at least check your oven with a good thermometer. Oven thermostats are notoriously inaccurate and can vary greatly through their range.  You don't want to set your oven at 160°F only to put your mash inside a 250°F chamber!
Good point.
Jeff Rankert
Ann Arbor Brewers Guild
AHA Governing Committee
BJCP National
Home-brewing, not just a hobby, it is a lifestyle!