OK, I’m having a hard time getting all my thermometers on the same page. I’ll have to invest in a REAL one and then calibrate the dial thermometers in the HLT and MLT. The spread is as much as 10º :o Also, with the 70Q Coleman Extreme I am not getting much of a temperature drop on infusion…
Using the consensus method I think the mash stabilized at 155, which is where I wanted it. But, there is the possibility that for a few minutes it was at, or near 170º Now I know the conversion process stops at that point, but is that because the enzymes can’t function anymore, or does 170º actually kill them?
I guess I’ll have the answer when I do my gravity readings on lautering, but in the meantime I would like to hear some input… thanks.
170F is enough to unfold the enzymes (can’t function), but it does NOT happen immediately. I would also expect it to be mostly reversible (doesn’t kill them) at that temperature, especially after just a short period of time.
The denaturation of enzymes is a function of temperature and time. So being at 170 for a short amount of time would not have killed them, but depending on how long actually was at that temp the b-amylase, which is the main creator of fermentable sugars, may have taken quite a hit. The result might be less fermentable wort.
I use a lab thermometer that is calibrated to NIST traceable standards and the great thing about is that they are fairly inexpensive. I think I paid less than $20 for mine.
We’re talking a few minutes here. Having the conflict I went with the hottest temp and stirred the mash lid off until it came down, but I may in fact be too cool now.
I REALLY need some decent thermometers. I can’t control what I can’t measure accurately…these $7 dial thermometers are toys.
That might not be directly comparable. Those aren’t barley enzymes, they’re from a thermophilic bacteria so we can expect different physical properties. For example the favored pH range is different. They’re also looking at purified recombinant protein, which is not the same as mash conditions where other cellular constituents are present.
It’s inherently difficult to put a time on this. Not only because we need to give a rate of denaturation instead of an actual time, but also because it depends on more factors than just temperature. Mash thickness for example is also one of them.
Thanks Kai. Those activity graphs are great, what is the original source for the data? Your website is really impressive, as always, there’s tons of stuff on there.
What I’d really like to see though, is activity curves for enzymes held at 70C for x minutes then cooled to different temps. It would give an indication of how rapidly it denatures and the reversibility of denaturation, that’s what’s important for oscarvan’s question.
Well…I hit my gravity dead on… so I got sugars. What kind of sugars I don’t know… We’ll see how it attenuates. As I said in my oriinal post, it may or may not have gotten to 170 depending on which thermometer is right…I have a gut feeling we’re going to be OK here.
Meanwhile I will order one of those lollipop thermometers and make calibration tables for the various thermometers.
The good news is that I hit all my volumes dead on today.
I like to use the bimetal dial thermometers for brewing since they’re so easy to adjust when you calibrate them. Then you need to keep referring to a table. And be sure to calibrate them in the mash temp range.
