Crazy mash temp swings

**EllisTX** · 10-11-2011, 06:50 PM

I did a BIAB Red IPA yesterday. I heated my mash water while I was grinding my grain. I overshot my temp and ended up at 167 so I left the lid off for a bit and then threw a few handfuls of ice in to lower the temp. When I got down to 160 I mashed in. My temp should have dropped to 154-155. The temp was stuck at 160. After a few more handfuls of ice and about 20 minutes it hit me that my thermometer may be wrong. Grabbed the back up and turns out my temp was already down to 133. This was at about the 30 min mark in the mash. I brought the temp back up to 154 and mashed for 45 more minutes. I guess I rambled a bit. Long story short, I mashed in around 160 then lowered my mash to the mid 130's for about 30 minutes before raising the mash back to 154.

Did I do an accidental step mash? What will the result be on my finished beer? My estimated og was 1.068 and I ended up at 1.065 so my efficiency was ok.

ReverseApacheMaster · 10-11-2011, 07:57 PM

I'm sure it's fine. It probably didn't have much of an effect. I think we've all screwed up a mash or two along the way.

It is a good example of why you need to stir your mash for several minutes (or more) before taking a temperature reading and the temperature should be taken from the thickest part of the mash. That will help you make this mistake again.

**EllisTX** · 10-11-2011, 08:46 PM

Thanks for the reply. I always stir the hell out of my mash. The issue here wasn't cold spots in my mash, it was the thermometer being stuck at 160.

**enkamania** · 10-13-2011, 04:40 AM

I feel your pain, I've gone through about 100 thermometers.

**MaxOut** · 10-13-2011, 12:16 PM

Your thermometer is arguably the most important tool you have when brewing. Get a thermometer you trust and one spare. Calibrate them with constants like boiling water and ice water. Throw the rest out. I had several thermometers when I started brewing and they drove me crazy. I eventually found one that I verified was the most accurate through calibration testing and put the rest of them in the round file. No looking back. Now I do not second guess measurements and can focus more on processes. I spent nearly a complete day testing and calibrating probes for my BCS and setting the coefficients based off one thermometer I trusted. Now I rest assured that the readings are accurate across the entire range instead of guessing. I had some thermometers that were as much as 30 degrees out. That’s a big difference when brewing and can make or break your intended recipe.

audger · 10-13-2011, 03:38 PM

heres some info about mash temperatures and enzymes-

the reason you mash starting at a lower temperature and increase it is because there are several different enzymes that work on different types of chemicals in the grain, and each enzyme works best at slightly different temperatures. see:
http://www.homebrewtalk.com/wiki/index.php/Enzymes

with enzymes, there is a low temperature range where they are mostly inactive; there is a prime temp range where they are the most active; and then there is a high temp that will denature and deactivate them. if you go over this temperature, they will perminantly no longer work (even if you bring the temp down again).

so mashing too low will only change the profile of the beer a little (due to a lower-temp enzyme working for longer than normal), and you can correct this pretty easily by raising the temperature. however if you accidentally bring the whole mash over the denaturization temperature of a certain enzyme, even if you then cool it down, that enzyme will no longer do its job.

Hethen57 · 10-14-2011, 05:40 PM

I will attest to what Audger is saying...I switched to what was supposed to be a really good thermometers without calibrating and after 5 batches of great brews, discovered it was reading about 15 degrees high! So when I was scrambling to get my temps down, they were already too low. The beers still came out great. Now I use the 2 thermometer system, with one or two spares on standby if I start getting inconsistent readings. My temps also jump around a little, depending upon where you put the probe and how recently you have stirred. In a cooler, there are probably a number of different temp zones in the mash, you just need to keep the average within an acceptable range and you should be able to make good beer.