35 replies to this topic

[jimdkc]

Been playing with brewing 1 gallon batches the last couple of weeks. I set the efficiency setting in BeerTools Pro at 70% when I developed the recipes, and the last 2 brews, I hit the expected numbers really close.Today I brewed an all-grain Hefeweizen (roughly 60% wheat, 40% pils, and some Hallertauer Mittelfruh for bittering) and Instead of hitting 1.051 as expected, I got 1.063! That's about 86% efficiency. I don't think I ever hit 86% before even brewing 5-10 gallon batches in my keggle!I'm not sure why this happened... Any ideas? I pretty much followed the same procedures I did the previous times.Jim

[MyaCullen]

Been playing with brewing 1 gallon batches the last couple of weeks. I set the efficiency setting in BeerTools Pro at 70% when I developed the recipes, and the last 2 brews, I hit the expected numbers really close.Today I brewed an all-grain Hefeweizen (roughly 60% wheat, 40% pils, and some Hallertauer Mittelfruh for bittering) and Instead of hitting 1.051 as expected, I got 1.063! That's about 86% efficiency. I don't think I ever hit 86% before even brewing 5-10 gallon batches in my keggle!I'm not sure why this happened... Any ideas? I pretty much followed the same procedures I did the previous times.Jim

wheat has less husk weight than Barley, though that should be accounted for in the brewing software?my first assumption is that you are getting the same efficiency with higher extraction values PPPG from the wheathmmm

[jimdkc]

Boil-off was a little more than expected, which would account for some of the apparent efficiency increase... but not all.Jim

[MtnBrewer]

No, boil-off doesn't affect efficiency at all.

[Deerslyr]

No, boil-off doesn't affect efficiency at all.

Agreed. Could have had a better crush. Wonder if there was anything different in his process this time over the prior two.

[djinkc]

Doing 1 gal batches it doesn't take much to affect OG. A little extra boiloff, a few extra ounces of grain, better crush................I guess it would make bottling a little more tolerable though

[MtnBrewer]

Agreed. Could have had a better crush. Wonder if there was anything different in his process this time over the prior two.

If the yield was off on his wheat by just a little bit, since there's such a high percentage of it, it could make it seem if his efficiency is higher than it really is.

[dmtaylor]

I know why efficiency is improved with smaller batches. I see precisely the same thing with my standard 3-gallon batches as compared to when I do the occasional 5-gallon batches. Assuming you are still boiling for an hour or more, and losing the same ~gallon or so as with a normal batch, you are effectively boiling off a huge percentage of the pre-boil liquor, which raises your apparent brewhouse efficiency considerably. In other words, if with a 5-gallon batch you might boil off 15% or so of your pre-boil liquor, with a 1-gallon batch, this percentage is more like 50%! Huge difference! I know I can very easily get >90% brewhouse efficiency on average with my 3-gallon batches. If instead I make a bigger 5-gallon batch, I know that my efficiency will drop a bit, probably into the low 80s. You must be seeing a very similar effect.

[MtnBrewer]

I know why efficiency is improved with smaller batches. I see precisely the same thing with my standard 3-gallon batches as compared to when I do the occasional 5-gallon batches. Assuming you are still boiling for an hour or more, and losing the same ~gallon or so as with a normal batch, you are effectively boiling off a huge percentage of the pre-boil liquor, which raises your apparent brewhouse efficiency considerably. In other words, if with a 5-gallon batch you might boil off 15% or so of your pre-boil liquor, with a 1-gallon batch, this percentage is more like 50%! Huge difference! I know I can very easily get >90% brewhouse efficiency on average with my 3-gallon batches. If instead I make a bigger 5-gallon batch, I know that my efficiency will drop a bit, probably into the low 80s. You must be seeing a very similar effect.

This is definitely true. But I understood him to say that the efficiency of this batch was much larger than his other 1-gallon batches.

[dmtaylor]

Ah, yes, I see.... I'll bet my bottom dollar then that it was the crush.

[jimdkc]

Could very well be the crush. The wheat looked to be considerably smaller pieces than the pils. Bought them both pre-crushed from a local homebrew shop (Bacchus & Barleycorn).And, yeah... with the first 2 batches, I thought I had the system dialed in pretty well at 70%... then the hefe surprised me. Guess I'll just have to suffer through a stronger-than-expected beer! Oh, Darn! Jim

Edited by jimdkc, 17 August 2010 - 12:29 AM.

[Malzig]

Running the numbers, a reasonable predicted efficiency would be ~84% from the batch sparge of a 1.063 beer, if you had a boil-off of ~21%. So your numbers look right to me for a small size batch that would be expected to have a higher evaporation. The only reasons to expect 70% efficiency from that size batch would be if you were terminating the mash before complete conversion (which is where crush comes into play) or you had a large dead volume in your tun.Evaporation, of course, only effects efficiency in that it forces you to put more water through the mash.

[MtnBrewer]

Running the numbers, a reasonable predicted efficiency would be ~84% from the batch sparge of a 1.063 beer, if you had a boil-off of ~21%. So your numbers look right to me for a small size batch that would be expected to have a higher evaporation. The only reasons to expect 70% efficiency from that size batch would be if you were terminating the mash before complete conversion (which is where crush comes into play) or you had a large dead volume in your tun.Evaporation, of course, only affects efficiency in that it forces you to put more water through the mash.

He would not get a boil off of 21%. It would be somewhere around 1 gal/hr so more like 50%.

[Deerslyr]

Correct me if I'm wrong, but his software is going to make some (accurate) assumptions about the potential of each grain. The software is also going to say that if he uses X pounds of grain to arrive at 1 gallon of wort, that it would be Y gravity. But its more fair to the process to say that he is using X pounds of grain to arrive at Potential Extraction of Z. From there, he can dilute it up or down to acheive his desired OG. The boil off has less to do with his arriving at Y gravity in 1 gallon of wort than the efficiency of extraction from the grains. Thre was something about his process, either at the crush stage or sparging stage, that affected his efficiency. Does this make sense?

[MtnBrewer]

Correct me if I'm wrong, but his software is going to make some (accurate) assumptions about the potential of each grain. The software is also going to say that if he uses X pounds of grain to arrive at 1 gallon of wort, that it would be Y gravity. But its more fair to the process to say that he is using X pounds of grain to arrive at Potential Extraction of Z. From there, he can dilute it up or down to acheive his desired OG. The boil off has less to do with his arriving at Y gravity in 1 gallon of wort than the efficiency of extraction from the grains. Thre was something about his process, either at the crush stage or sparging stage, that affected his efficiency. Does this make sense?

Sort of. The software actually doesn't make any assumptions at all. You tell it the expected yield from the grain you're using. If you use the wrong yield, well it's garbage in, garbage out. So based on that yield, it calculates how many points of sugar would be extracted for a "perfect" mash & sparge. Then you measure the gravity and volume, which gives you the actual points extracted. Actual divided by theoretical is efficiency. Since boiling doesn't affect the points of sugar in the wort, boiling does not affect efficiency.

[Malzig]

He would not get a boil off of 21%. It would be somewhere around 1 gal/hr so more like 50%.

I wasn't trying to make any prediction as to his evaporation, rather I was attempting to say that it would only take a boil-off of 21% to get his OG of 1.063. Even greater evaporation would mean increased sparging volume and higher efficiency. The OP seemed to think that his OG was high, while it's well within what I would expect, even with a conservative (for a small batch) evaporation rate of 21%. I've never managed to get my evaporation below ~0.75 gal on small batches. Maybe with the right kettle design...

But its more fair to the process to say that he is using X pounds of grain to arrive at Potential Extraction of Z. From there, he can dilute it up or down to acheive his desired OG. The boil off has less to do with his arriving at Y gravity in 1 gallon of wort than the efficiency of extraction from the grains.

This part is basically true, and easily calculated, except that it is dependent on the amount of water run through the grain. So, basically, Potential Available Extract depends on a proportion of total runnings volume to grain weight. Then, OG is dependent on how much that is then concentrated during the boil. So, 50% efficiency can arrive at the same OG as 75% if you boil-off twice as much. Sorry if that's all painfully obvious... perhaps I misunderstood what you were getting at.

[MtnBrewer]

I've never managed to get my evaporation below ~0.75 gal on small batches. Maybe with the right kettle design...

Evaporation rate is essentially constant. This is why I prefer to express it as a rate rather than a percentage. My evaporation rate is 1.15 gal/hr whether I'm boiling 2 gallons or 10.

[Malzig]

Evaporation rate is essentially constant. This is why I prefer to express it as a rate rather than a percentage. My evaporation rate is 1.15 gal/hr whether I'm boiling 2 gallons or 10.

I use a smaller kettle for smaller batches. My evaporation will go up for a 3 gallon batch from my usual ~1 gallon/hr to ~1.5 gallon/hr. If I turn the heat down as low as needed to maintain a rolling boil, I can temper the evaporation rate to ~0.75 gallons per hour for a 3 gallon batch, or 20%. I'd prefer if that was below 15%.Anyway, the percent value is only a means of determining the expected efficiency. For a given sparge water to grain rate, the percent evaporation is more easily converted between batch sizes. From my previous example: if you boil off 21% to hit 1.063, you should be able to expect 84% efficiency for a 1.063 beer whether it's a 1 gallon batch or a 10 gallon batch. If you boil off 1 gallon from a 1 gallon batch your efficiency should be higher, while it would be lower if you boiled off 1 gallon from a 10 gallon batch.Needless to say, on brewday I'm more interested in gallons evaporated and never think of what percent that might be.

[Deerslyr]

This part is basically true, and easily calculated, except that it is dependent on the amount of water run through the grain. So, basically, Potential Available Extract depends on a proportion of total runnings volume to grain weight. Then, OG is dependent on how much that is then concentrated during the boil. So, 50% efficiency can arrive at the same OG as 75% if you boil-off twice as much. Sorry if that's all painfully obvious... perhaps I misunderstood what you were getting at.

I respectfully disagree with you. And no, your point is not obvious. I don't think that you can force more sugar out of the grain just by passing water through the grain bed. Otherwise, if you set aside the astringency problem, we should all be having 100% extraction. That is clearly not the case.Boil off has nothing to do with extraction of sugars from the grain. Efficiency is about the actual amount of sugar that is in the wort in relation to the total amount of sugar that was initially in the grain. Period. If you pour a pound of sugar into a pot with 3 gallons and boil it down to 1.5 gallons, you still only have a pound of sugar in it. Yes, your gravity is higher than when you started, but the amount of sugars in your pot remains the same. Boil that 1.5 gallons down to .5 gallons and you still only have a pound of sugar in the pot. A single grain of barley has X amount of sugars available to give the brewer. If the brewer is good at what he does, he can get as much sugar out of that grain as he can. No amount of boiling will change the amount of sugar he has... only the density of the wort.{edited for tone and clarification of opinion}

Edited by Deerslyr, 17 August 2010 - 11:44 AM.

[MtnBrewer]

Anyway, the percent value is only a means of determining the expected efficiency. For a given sparge water to grain rate, the percent evaporation is more easily converted between batch sizes.

Actually I think the opposite it true provided you're using the same kettle. If I do a 10 gallon batch I know that I'll boil off about 1.15 gal/hr. If I do a 5 gallon batch, I know that I'll boil off about 1.15 gal/hr. However the percentages are very different between one batch and the other.

From my previous example: if you boil off 21% to hit 1.063, you should be able to expect 84% efficiency for a 1.063 beer whether it's a 1 gallon batch or a 10 gallon batch. If you boil off 1 gallon from a 1 gallon batch your efficiency should be higher, while it would be lower if you boiled off 1 gallon from a 10 gallon batch.

That's the thing. You won't boil off the same percentage between a 1 gallon batch and a 10 gallon batch.