24 lbs pils malt, 13 gallon boil volume, 10 gallon batch size.
First gravity reading (taken from mash tun) = 1.066
Last gravity reading (taken from BK) = 1.049
For those of you with experience diving into the minutia of numbers, what exactly does this tell us?
Are you shooting for 10 gallons in the kegs/bottles or in the fermenter? How much did you leave behind in the mash tun or boil kettle? What was your boil volume? You can start dialing things in when you get those numbers. Starting with that, you can use standard assumptions about extract, as per the beer smith article below. If you really want to dive into the details, malt lot analysis sheets can get you a more precise number, but I haven’t dove into that. A few more learned members have talked about it, but this method works pretty well.
Looks like a bad measurement in the mash tun. Maybe the wort wasn’t mixed thoroughly.
The goal was 11 gallons final volume into the fermenter. Boiled 13 gallons, ended with 10 due to vigorous evaporation. Left behind 1.5 gallons in the mash tun. We squeezed every last drop from the boil kettle.
That 1.066 reading was from the mash, prior to run off.
I ran the potato math and even assuming 100% conversion efficiency (which isn’t likely) there’s no way you got 1.066 from the mash.
It’s impossible to get 1.066 from 24 lbs of grain? This was before any run off. The mash water volume was 8 gallons.
If so, what about the 1.049 in the BK? These numbers were taken with a refractometer. The mash Brix was 16.2.
I agree. Impossible. You’d have to have 105% mash efficiency or something. I’ve seen 94% before, but never 105%.
(EDIT: If you saw my previous response above, nevermind it, deleted.)
You’re especially going to expect a huge reduction in brewhouse efficiency from this point, if 1.5 gallons of wort was left behind in the mash tun. Wasted sugars.
One of the two readings is completely wrong, if not both. So, check all your calibrations. What does your refractometer read in plain water? What does your mash thermometer read in boiling water? Ice water?
You can get above 100% if decocting since it makes available some starches that have to be boiled and popped to access.
Not saying it’s the case here. Just in the of of efficiency.
Thanks. Makes sense.
Beta glucans refracting light?
Perhaps absorption loss?
The runoff was halted as we hit our target of 13 gallons in the BK. The remaining wort in the mash tun was extremely weak at this point, thus the reason we dumped it down the drain.
BTW…the numbers here reflect what we have experienced in previous brews, being an OG ranging from 1.055+.
Yes, the refractometer was calibrated with distilled water.
The issue here is that the mash gravity reading is not possible. Given that there was a reasonable value for original extract, the mash extract was more likely on the order of 1.040 or so.
I didn’t run hard numbers so I’m off by about +/- 0.02 S.G. But in the wheelhouse enough to know that it was merely a bad reading from the mash.
Is this a no-sparge or sparge batch?
Sugar thrown away is sugar thrown away.
Check your mash thermometer. And how’s the mash pH?
I’m just here to add if this was a single infusion, not only is it wrong, it’s WILDLY wrong.
A refractometer measures refracting light not specific gravity.
If only sugars and sugar polymers are refracting, then you have a very good correlation to specific gravity.
Otherwise, you don’t.
Ours has a dual scale, it read 16.2 Brix on the wort right from the mash recirculation. We did a full recirc of the mash for 45 minutes, and did a 150-155 degree single infusion for a little over an hour.
Our conversion chart showed 16.2 = 1.066.
I would not worry to much. You definitely did not have higher sugar concentration in the mash vs the boil.
Something messed your mash reading.
Unless you can reproduce it in the future you should not worry.
And if you can reproduce it, take a hydrometer sample to validate.
We will brew the same beer again in a few days, so will have the opportunity. Our refractometer is spot on for calibration, just checked it a few minutes ago. And (so far) our brews have been extremely good. Like a brewing partner said…“Each new beer we brew is my new favorite beer!”