Poor (or lazy) man's method of measuring partial mash efficiency?

[jsweet]

So I'll start with maybe a sort of funny story... I did my first partial mash the other day. I was totally unprepared, as I had somehow talked myself into thinking it was just an extract w/ steeped grains recipe pretty much up until the time I was in the LHBS grinding a bunch of ingredients that I knew damn well had to be mashed Laugh if you want, I think I had this phobia about partial mash, so I looked at the recipe and said, "Yeah, I can do that... as long as I tell myself it's an all-extract recipe!"

I know the process is basically the same, except that temperature control is more important. Also, I usually don't use a grain bag, I just scoop the spent grains out with a strainer, but this recipe had a bunch of flaked wheat and flaked oats and stuff... so I had to improvise... but I think it worked out alright on that front, except that the grains were maybe a little bit more packed together than is ideal.

Of course, the day I had planned to brew, my older son started coming down with a fever. We gave him some medicine and thought he was better, so I started brewing anyway over my wife's objections -- and then he got worse. D'oh. I mean, he was fine, no symptoms other than the high temperature and a little cranky, but all of a sudden my wife sorta needed some help. So I spent about 90% of the brewing session holding my younger son, 4 months old.

You'd be surprised how much you can do one-handed if you have to! To make matters worse, I was running in and out of the kitchen to check on my older son and wife. Given that, I think I did a damn good job at temp control, all things considered: I was going to mash for 45 minutes, and it was right between 151F and 155F for the first half hour. Then the temperature started to drop, so I turned up the burner, then got called into the other room, and well... I guess that was my "mashout". It climbed to about 165F, and I never got it back down.

And sparging was entirely out of the question, not least because even if I did figure out how to do it one-handed with my complete lack of preparation of equipment, I wasn't about to be pouring 170F+ water all over the place while holding an infant in the other hand...!

Luckily, I wasn't overly worried, because the recipe was such that even if I got zero fermentables from the mash, there was enough extract that it still ought to have been a decent beer, if perhaps a bit thin. And so what was my efficiency?

Well, I know I've read how to calculate it before, and I'm sure I could just look it up again... but I was wondering, if I just play around with the efficiency numbers in Beersmith until its predicted OG matches my measured OG, that's pretty much the same thing, right?

If so, I got about 43% efficiency, which I think is pretty good considering the circumstances! Just wondering if I can trust that number, or if I really have to go to the work of calculating it for real. Comments?

 

[Dogphish]

did you measure the specific gravity with a hydrometer?

 

[jsweet]

Yes. I know I can calculate it from that, but that seems like I lot of work. If I plug in 43% efficiency to Beersmith, though, its predicted OG matches the OG I measured with my hydrometer. I'm just wondering if that's just as good as actually calculating it, cuz I gotta say, I found that a helluva lot easier...

 

[Calder]

Yep; just plug the fermentables into a recipe in Beersmith, adjust the Brewhouse Efficiency until you get your OG, and you are good to go.

This assumes your OG measurement was correct. 43% seems pretty low. Are you sure it was mixed well? Did you adjust for temperature.

 

[jsweet]

This assumes your OG measurement was correct. 43% seems pretty low. Are you sure it was mixed well? Did you adjust for temperature.

Well, like I say, 1) this was a partial mash, which as I understand it -- please correct me if I'm wrong! -- typically have a somewhat lower efficiency anyway; 2) the grains were packed together pretty tightly, possibly reducing the surface area exposed to the water; 3) I lost control of the temp after 30 minutes and basically did an early mashout; and 4) I didn't sparge AT ALL. Given all of that, I'm thinking 43% is not unreasonably low...

I did use top-off water, but I do believe I mixed sufficiently. I know people say that is nigh impossible, but all of my OG readings have always made sense, regardless of whether I top-off or not. (A few of them were unexpectedly low, until I discovered that where I thought was the 5-gal line in my carboy was really about 6 1/4 gallons -- going back and adjusting the math based on that predicts the measured OG almost perfectly)

It's possible that adjusting for temperature would have made some difference. When I started chilling my wort to 65-70F before transferring to the fermenter and topping off, and started fermenting at ~60-62F, I also stopped bothering to adjust my hydrometer measurements for temperature since it only makes a point or two difference at that point. If we assume the wort was way hotter than usual when I mixed -- say 80F, and I *know* it wasn't that hot, not by a long shot -- that would bump the efficiency up to the mid-50s. More realistically, it might have been more like 70F, which would only increase the efficiency to the high 40s. So I don't think there is a huge effect here from me not bothering to adjust for temp.