Almost exactly two years ago we switched over from using an insulated mash tun to a direct-fire recirculating mash tun. I’ll admit that it has been quite the challenge. The reason for doing so was to have greater control of our finished products without doing infusion mashing, which I, personally, think is terribly inefficient. One of the problems we have encountered though falls into the realm of heat control. This is one of the topics that I have been studying for the better part of a year in an attempt to full understand.
I have noticed over some testing several different beers styles we have made that the finished product turned out a little too sweet. My first thought was perhaps there just were not alpha acids in the hops to balance out the sweet wort. This is a common problem with older hops, and I’ll be honest, sometimes running tests is the best way to clean out old ingredients.
The first batch was a simple pale ale:
5.5 Gal, 5.0% abv, Fg 1.050 – medium body.
American Ale yeast.
10 pounds of Pale Ale Malt
A few ounces of acid malt
1 oz of Mandarina Bavaria hops at 60
1 oz of Mandarina Bavario hops at 2
Fermentation 18 days, with a week in the keg at 12 psi, 44 degree serving temp.
The beer was very sweet, where as all the calculations I programmed in were supposed to lend a mildly bitter and light pale ale.Like the name implies. Carbonation turned out ok.
For the second batch, same as the first, the difference being that this time I upped the hops to 1.5oz for both the bittering and the aroma. Again, the beer was a bit t0o sweet.
This really got me thinking… I backtracked and did discover some areas in my process where it could pay to have a bit more attention to detail.
For starters, I think I had become too dependent on my thermometers. I rely on two Thermoworks models, I use this one for stabbing the mash to get readings: Thermoworks LongStem Probe And I use this one with the waterproof probe for getting a reading at the bottom of the grain bed but on top of the false bottom: Chef Alarm.
The problem that I have with any thermometer is the calibration. The standard method for calibrating to a cold source is to take a cup, fill it comepletely with ice, pour water over it, stir it around then let it sit for 3 minutes. In theory, this will equalize at just around 32-degree F. Regarding the ChefAlarm, I’ve done that. I stuck the probe in the water, then calibrated to 32F. However, I found that if I take that same cold-calibrated probe and stick it in boiling water, it will only read 209F. I live in Los Angeles, so, elevation-wise, my boiling point should be pretty darn close to 212.0F.
My long-stem probe is not able to be calibrated, and thus I don’t really know how accurate it is or isnt. The website says it is calibrated to within 1.8 degrees +/-. Thats fine and dandy for soups but I would like a bit more for my mashes.
So, what is my conclusion here? Well, I don’t exactly know of a method to calibrate at a middle ground, somewhere around 150F. That would be ideal. My thinking is that when I am doing a mash at 150F, which should lend a medium-light body with a somewhat dry finish, I am actually closer to 154F, which might be chopping the sugars into way-too-easy-to-ferment bits, thus sweetening my beer unknowingly and unintentionally.
I’ve yet to calibrate the ChefAlarm based on boiling point mainly for one reason. I have noticed that while water boils at 212, sometimes the bottom of the pot that the probe would lay on can reach 215 degrees. If I dangle the probe just a bit above the bottom of the pot, the probe can read 210…
If i was cooking a turkey these minor variances wouldn’t mean much, but four degrees in a mash can mean the difference between a sweet wet beer and a malty dry beer.
Another problem which I have been trying to iron out since switching to the direct-firee recirculation mash-tun is where to take the temperature reading and when does the enzymatic activity take place. Like stated above, one probe is laying on the false bottom which is where I usually take my reading. This week I purchased a small device which will allow me to take a reading on the outlet valve of the recirculation.
Event though the probe might be reading 148 in the grainbed itself, perhaps the direct fire in the kettle is raising the liquid temp a few degrees before it exits for recirculation? If that is the case, does the water strip the enzyme from the grain and they interact the whole time they are recirculating, thus experiencing this temperature rise near the bottom of the tun? or does all the enzyme activity occur within the direct contact of grain-to-water above the false bottom?
Its a lot to process and I really should figure this out. Thats the experimenting that is going on here. Someone has either told me or i’ve read somewhere that it doesnt matter what the equipment says as long as you make it work for you. If thats the case, maybe I should just make mental notes that a mash at 148F is really 152F, but I don’t like that idea at all. If you start with innaccuracy you really cant blame anyone but yourself when things dont go according to plan.
If you’ve had a chance to check out my book, Decent Home Brewer, Bad Learner, which basically highlights all the problems and solutions we’ve had getting our shop up to speed, you can see why this kind of problem is a somewhat fun problem to have. Especially from an educational point of view.
Anyway, if youve got any input I would love to hear it.