Partial mash temperature problem.

[T-Dan]

I did a partial mash today of an American Brown Ale. I came pretty close to hitting my temps for the step mash, or so i thought.

During the boil afterwards, i noticed my new floating thermometer was reading high (220 degree boil). So i put in another thermometer and found out the floating thermometer was reading 7 degrees high. What this means is that my mash temps were off. Protein rest at 125 (which is ok) beta rest at 135, alpha rest at 145, and batch sparge at 158 or so. First two rests were 30 minutes, alpha was 82 ( took that long to get a good iodine result), and 10 minute sparges.

So my question is, what can i expect for results on this beer? How bad might i have screwed it up?

Thanks, Dan.

 

[Golddiggie]

It may not be 7 degrees off across the entire range of temperatures. Only way to know would be to test with a known accurate thermometer, at those temperatures. At most, the beer will finish with a lower FG (more dry, less body).

BTW, why did you intend to sparge at 165F? The typical sparge range is 168-172 (to denature the enzymes).

IF it really does finish with a LOW FG, you could try adding non-fermenting sugar to it (like lactose) in order to give it more body. I've never done that, nor needed to do that, so you'll need to find out how much to use to get what you want, IF you go that route.

 

[T-Dan]

Thanks for the response. I was aiming for 168 on the sparge. I did two sparges and did get the 168 on the second one. The first one was at 165. Or so i thought.

I will have to check the readings at different temps as you suggest. But judging by how it is built, i think the scale in the floating tube slid down....

 

[Golddiggie]

That's one of the reasons I wouldn't trust thermometers made that way. I have one of those lab thermometers (liquid filled) but have a hard time reading it. So I went with digital thermometers. I went through a few (couldn't survive the boil/moisture levels) before getting good ones. Now, I'm using thermal sensors connected to a thermometer that sits a few feet away from what's being measured. The temperature readings are more precise than I need, which is good. Of course, the gear I'm using isn't cheap, which is probably why more home brewers don't use them. Still, you can get quality thermometers from Amazon without dropping a lot of money. For about $30 you can get a waterproof thermometer with an 8" stem on it. That way your hand isn't too close to the mash, or the boiling wort.

 

[agentEhrman]

I'm on my second cheap $20 digital probe thermo and I can tell you from my experience, just shell out the money to get a good one. My first went down due to a little moisture. My second one has some major issues with accuracy below 100 degrees, and cooling to correct pitching temps is pretty important. Get one that's waterproof and that you can calibrate. And grab a lab thermo to check accuracy and or calibrate. The thought of spending $50 or more on a thermo is tuff for me to get over, but I have now spent about $40 and don't really have anything..

 

[bobbrews]

First, calibrate your thermometer prior to brewing, or get a new one if it's faulty. I always calibrate my digital therm to be on the safe side.

Second, I wouldn't complicate this more than it needs to be. Exact mash temps don't matter as much for partial mash beers as they do for all grain beers.

Extract was most likely mashed from grains that were held in the mid 150s (I'll say 152-156 on average depending on the maltster).

For this reason, I mashed in the upper 140s to balance out somewhere at 150 F.

I find that if you mash high, for what is intended to be a drier partial mash beer, then the residual sugars from the higher extract mash temp will leave you with a beer that is too sweet.

 

[T-Dan]

First, calibrate your thermometer prior to brewing, or get a new one if it's faulty. I always calibrate my digital therm to be on the safe side.

Second, I wouldn't complicate this more than it needs to be. Exact mash temps don't matter as much for partial mash beers as they do for all grain beers.

Extract was most likely mashed from grains that were held in the mid 150s (I'll say 152-156 on average depending on the maltster).

For this reason, I mashed in the upper 140s to balance out somewhere at 150 F.

I find that if you mash high, for what is intended to be a drier partial mash beer, then the residual sugars from the higher extract mash temp will leave you with a beer that is too sweet.

Interesting points. Thanks for the info!

I did use 3.3 lbs of LME in the boil, so that would offset some of the 8 lbs of grains i mashed.