You do, including the volume increase due to dissolved sugars. Using Kai’s chart, I’m calculating more than 100% conversion efficiency (he predicts ~1.077 at 100% conversion from a 1.61 qt/# mash), unless your potential extract was particularly high or your grain was particularly dry. Did you stir the mash well before you took the sample for the pre-sparge gravity?
~64% would be the mash efficiency, not the conversion efficiency, from that first runnings.
It looks like you are calculating your potential as 37. That might be a little high. If you are using any specialty grains, it is apt to be closer to 35-36 on average. I just mention this because I suspect you are underestimating your mash efficiency.
However, be sure to stir your mash well after adding your sparge water, or you will lose a lot of efficiency for you sparge.
[quote]If not, I think I’m starting to understand the concept of mash vs. brewhouse efficiency. One is a measure of how much sugar you converted, the other is a measure of how much of that sugar actually makes it into the kettle vs. being left in dead space, water absorbed by the grain, etc.[/quote]Brewhouse efficiency is just a measure of the efficiency of your volume transfers multiplied times your mash efficiency. If you only manage to get 80% of your volume out of your kettle (5 of 6.25 gallons), due to your desire to leave break material behind, and you had 80% mash efficiency, then you would have 0.8 x 80 = 64% brewhouse efficiency. In my mind, it’s really only a concern for professional brewers that need to know where they are losing money. It doesn’t tell you anything about how well your mash went that isn’t obscured by your ability to make transfers.
It is definitely quite dry. I don’t have much to compare it to, but disturbing the sack, even slightly, induces a huge puff of dust, fwiw.
Yes, vertically and horizontally (i.e., not just in a circle around the kettle, but also in a circle from top to bottom).
I’m not using an average for my calculations. Here’s the breakdown I’m using:
Breiss 2-row: 37 pppg (370 @ 10 lbs)
Breiss c-60: 34 pppg (51 @ 1.5 lbs)
Dingemans Biscuit: 35 pppg (17.5 @ 0.5 lbs)
Muntons Choco: 28 pppg (10.5 @ 0.375 lbs)
That makes 449 pppg grain bill potential, which is 89.8 for 100% conversion via 5 gallons of water. I got 82. Are there any glaring errors in how I’m calculating this?
Regarding pppg ratings, I haven’t really been able to find good info on that for the given brands I’m using. Hopville lists Breiss at 34 pppg, but then it lists Dingemans at 50 pppg. The latter seems basically impossible, so I just used Palmer’s for everything, even though the numbers are generic. Are there any good sources for the various brands?
Re: stirring after mash infusions, I am more and more careful about it with each batch, and really took my time with it this round.
Yeah, I basically ignore that measure, I’m just trying to get the parameters of the various efficiency measures really clear in my head. Thanks for the distinction re: brewhouse. Your point about it being useful primarily to commercial breweries is a good one, and is a nice retroactive validation of my tending to ignore it .
Yes; as Slothrob said, the sugars in solution will increase the overall volume. Maximum SG from a 1.6 qt/lb mash would be about 1.080. Using your assumptions about potential extract, the overall weighted average is 78.5%, so it would be closer to 1.076. 1.082 is far enough off that you have to have a measurement error somewhere (or the potential extract of one or more of the malts is much higher than your assumptions).
Does this mean after accounting for increased volume due to dissolved sugars? And, how did you derive that %? Or, perhaps a better question is, what is the formula for coming up with max extraction potential? I thought it was just a matter of calculating total potential pppg and dividing by volume in, but it sounds like I’m missing a critical parameter…I have to be, as my calculations put me at 91%, but you guys/Kai’s chart have me at 100+.
As a result, I’m pretty confused. It sounds like calculating conversion efficiency requires that you use the total volume resulting from mash in AND dissolved sugars? That seems counter intuitive to me. It seems as though infusion volume would be paramount when determining the density of sugars dissolved in that infusion volume, even though the volume has increased (er, been transferred from the grain to the water) during the mash.
All that said, I’m fairly confident that if any measurement errors occurred, they happened when I weighed the grains. If so, it would be interesting to try to calculate how much extra grain went in. And, I’ll have to devise a way to test the new scale. It definitely weighed a little lighter than the LHBS scales (2 lb bags weighed at LHBS were about 1.9 at home), but I’m cynical/paranoid enough to feel it’s possible they rigged theirs to increase profit margins .
Does this mean after accounting for increased volume due to dissolved sugars? And, how did you derive that %? Or, perhaps a better question is, what is the formula for coming up with max extraction potential?[/quote]
No, that’s the potential extract for the grist. All I did was use your numbers, 449 point-gal and 12.375 lb:
449/(46.21*12.375) = 0.785
46.21 point-gal/lb is the definition of 100% potential extract (sucrose). There’s no formula for potential extract; it’s a quantity that’s set, and reported, by the maltster(s).
Since Kai’s table assumes 80% potential extract and projects an SG of 1.077 at 1.6 qt/lb, it would be closer to 1.076 at 78.5% potential extract.
Right, because you have no way of measuring the gravity divided into the infusion volume only. By definition, conversion efficiency is the amount of sugar dissolved. It would be impossible to determine it before the sugars are dissolved.
OK. I think I’m starting to get it. If we use Palmer’s numbers for 2-row, max p/p/pg is 38 (I was looking at lager, which is 37, pale ale is 38…d’oh!), which is 46.9% of max yield (81). I’m assuming Palmer just rounded for simplicity, hence 46.9 instead of 46.21?
For my purposes (recalculated using 2-row ale malt):
459/12.375 = 37, which is the average potential pppg for the grist.
37/46.21 = .80, which is pppg as a percentage of the max yield
Is max yield based on the average amount of starch/sugar in a given kernel of barley?
I think what’s throwing me off is the idea of measuring the density the sugars add to the mash-in volume AND using those dissolved sugars to adjust that volume. It just seems strange to me, but so long as I know that’s how it’s done, that’s all that matters.
OK, thinking about it as measuring solution density helps. The sugar is part of the solution, so the whole volume is what counts.
OK, I’ve read Kai’s efficiency page like 8 times, but I just discovered the spreadsheet. Heh. Using that, I’ve determined that my grist may have weighed 13.5+ pounds than 12.4 (1.082 = 100% conversion efficiency for 13.5 lbs). Crazy. Hopefully that’s where the problem is, exclusively.
Assuming 13.5 pounds is correct, that pushes my mash efficiency down to 74.5, which is a number I would be more than happy with if I can hit it consistently. Hopefully my grain wasn’t more than a pound off or else I still haven’t really improved efficiency at all.
More or less. It’s just the proportion of the malt that’s soluble starch.
If you like, you can do it the way you were. You just have to multiply your SG reading by ~0.92 to account for the volume of the sugars. (After converting into an absolute gravity unit like °Plato.) All you’re doing is calculating a fraction, so you can multiply the numerator and denominator by the same constant without changing the result.
Hrm…don’t I need to adjust the volume measurement, not the SG reading? 82 * 0.92 = 75.4, which is 98% of potential extract and means maybe my weights were OK?
Anyway, the hang up was more conceptual than methodological, as I don’t have a problem following a method even if I don’t understand it completely. That said, thinking about it as measuring solution density as opposed to mash-in volume density clears it up.
I just hope the scale is the only issue. All vessels used to measure my water have been calibrated via 1 quart measuring cup and checked against a floor scale. The floor scale isn’t ideal, but everything was quite close to a multiple of 8.3 lbs per gallon.
PS - thanks for being so responsive! This is all very informative.
So, I bought a decent digital food scale and checked my el-cheapo mechanical food scale against it. The cheap one is reasonably close, although somewhat inconsistent. I did weigh my remaining c-60 to see if there was a full 8 oz left, and it was down at ~6 oz. I’ll have to check my 50 lb sack of 2-row and see if there’s less than 40 left.
In the meantime, a10t2, do you mind clearing this bit up for me if/when you have a moment?
Hrm…don’t I need to adjust the volume measurement, not the SG reading? 82 * 0.92 = 75.4, which is 98% of potential extract and means maybe my weights were OK?[/quote]’
Thanks!
Hrm…don’t I need to adjust the volume measurement, not the SG reading? 82 * 0.92 = 75.4, which is 98% of potential extract and means maybe my weights were OK?[/quote]
Same thing. SG is just a ratio, so multiplying by a constant and dividing by its inverse give the same result. The sugars in solution increase the volume by about 8%, so the SG is about 8% lower than it would be if the volume didn’t change. (The 8% isn’t constant, by the way, so doing it like that would would introduce some error.)
1.082 is 19.8°P * 0.92 = 18.2°P = 1.0750. I have to be honest, I don’t remember what you were measuring/estimating at 1.082.
1.082 was the SG of first runnings. Total infusion volume up until that point was 5 gallons. Using 8% volume increase*, 1.082 is the SG for 5.4 gallons of wort.
All that said/understood, is Kai’s chart using mash thickness is meant to account for all of this? I.e., an SG of 1.082 is probably too high for ~5.4 gallons of wort sans a measurement error somewhere? At any rate, I’ll still check the 50 lb sack when I get home to see if it’s an extra pound lighter than it should be (an extra pound over the intended grain bill would’ve been necessary to get to ~1.082 via Kai’s chart).
*It makes sense that 92% SG/8% volume is changeable, as it would be dependent on the amount of sugar absorbed.
No, I kept the sample covered. It almost has to be the grain. I really hope so. I’m glad the remaining c-60 weighs slightly less than it should. The bowl I used to weigh everything couldn’t hold the full 10 lbs of 2-row, so I had to weigh it out over three batches, making stacked errors a possibility. Fingers crossed…
Hrm…it looks like being short just over 1 quart may also explain this. And, JUST when my mash out water came to a boil, my mom discovered that my 2-year-old had removed his diaper during his nap and…well…yeah. I turned the burner off, went to clean up his crib for 15 - 20 minutes, then returned the water to a boil and poured it in. At this point, I have no memory if I covered the pot while I was away. 1 qt would be a lot to lose in 15 - 20 minutes, especially since I stopped the boil, but if I left it uncovering that may have played a role.
I just mashed 10 lbs 14 oz (10.875 lbs) of grain in a total pre-sparge volume of 18 quarts, for a mash thickness of 1.66. 1st runnings gravity was 1.074. Kai’s chart lists 1.63 at 1.076 and 1.72 at 1.072. 1.074 seems reasonable for 100% at 1.66. Sweet!
SG for total wort collected (a hair over 7 gallons) is 1.046, which is 80% efficiency. Awesome! Now, to work on hitting these numbers consistently.
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