Really Missed My Temps

I'm looking for a little advice from you guys. Yesterday I brewed a porter on my new brewing set up. It's a 3 keg all grain system but it was my first time using it so I don't have anything dialed in yet. I was so caught up in doing other things during the brew day that I didn't keep an eye on my mash temps. About 30 minutes in I checked and it was about 120 degrees. Ouch. I was right at 150 when I walked away and within 30 minutes I lost 30 degrees. I tried heating it up then I thought I was burning the grain, then it shot up to 180 degrees, so I got some ice.......and on and on the brew day went.

Anyway, my efficiency was only about 50 something percent and my OG came in around 1.042. Beersmith was looking for something in the 1.056 range (I can't remember the exact numbers right now). I was so frustrated that I just threw it in the carboy, added my yeast, and away we go. At about 3 AM I woke up kicking myself because I have a bag of light DME just sitting in my kitchen that I didn't even think about adding to get my OG up.

OK, so here is my question. What would you do if this was your beer? It's been fermenting for about 20 hours now and was pretty active this morning when I left for work. Would adding DME tonight be something to consider? Should I just let it be and see what I end up with? Any thoughts or suggestions would be greatly appreciated. Thanks all!

First off, your beer is going to be fine. It will be a lower alcohol porter, but should still taste fine.

Second, here's what your mistakes actually did:

1) Maintaining mash temps is very important. Different temps activate different enzymes in the beer that extract starches differently from the grain. Anything under 150F or so, and the enzymes that are active break down the starches into mostly simple, short chain sugars that the yeast can easily consume. That means less malt character/lighter body, and a dryer beer. Anything above 150 or so, and the enzymes that are active break down the starches into both simple, short chain sugars that the yeast can consume and a % of complex, long chain sugars that the yeast can not. That leaves your beer with more malt character/heavier body from the residual malt sugars.

In your case, you started at 150F but pretty rapidly lost heat down to 120F. You would have had the enzymes active that will lead to a lighter body and more attenuation due to mostly simple sugars, however, because you lost so much heat, obviously your efficiency suffered.

Now, where you are. You can definitely add DME, but you want to limit it so it doesn't change the character of your porter. Take about a pound (assuming this is a 5 gallon batch), boil it on the stove long enough to dissolve it, then cool it to very close to your fermentation temp and add it.

Good luck!

Topher is pretty spot on, the only thing I would add moving forward is it will be difficult to figure out exactly where your FG will wind up since it is difficult tell what type of conversion of what sugars you got. You may wind up maltier with a higher FG or drier with a lower FG, kind of a crapshoot

I agree with both of the above posts. Adding DME now might get you closer to what you were aiming for, but will make gravity measurements less than exact.

When I did this same sort of thing awhile ago, I believe I read that 1 lb of DME is approx 8 gravity points. So by adding 1 lb DME you could estimate 1.042 + .008 = 1.050 OG to closer determine the resulting abv.
**You should definitely double check my numbers in case I am remembering wrong.

Thanks for all your responses. Topher, that was probably the simplest/best way I've had that explained to me so thank you for taking the time to share. I've decided to leave the brew as is and see what comes of it. It will be beer regardless and with the lower ABV maybe, just maybe, I'll have a few less drunkards around during the holidays