35 replies to this topic

[MtnBrewer]

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.

If you sparge more, you will rinse more sugar from the grain whether you fly sparge or batch sparge. Efficiency is a strong function of sparge water volume.

[Deerslyr]

If you sparge more, you will rinse more sugar from the grain whether you fly sparge or batch sparge. Efficiency is a strong function of sparge water volume.

Here is the thing I was trying to avoid confessing to. I have oversparged to the point where the gravity reading at 60 degrees of the truly final runnings was zero. I boiled down to my target volume of 6 gallons. My OG was spot on target for what BeerSmith had said I should be at with a Brewhouse Efficiency set at 78%, with 12 pounds of grain for a final volume of 6 gallons. Please explain to me how I left 22% of the sugars in the mash tun?

[MtnBrewer]

Here is the thing I was trying to avoid confessing to. I have oversparged to the point where the gravity reading at 60 degrees of the truly final runnings was zero. I boiled down to my target volume of 6 gallons. My OG was spot on target for what BeerSmith had said I should be at with a Brewhouse Efficiency set at 78%, with 12 pounds of grain for a final volume of 6 gallons. Please explain to me how I left 22% of the sugars in the mash tun?

I don't think you left 22% of the sugars in the tun. The only way you could have extracted most of those sugars is to do a congress mash. Also there may have been incomplete conversion or the grain didn't have the yield you thought it did to start with.In a normal situation, when you don't oversparge, some sugar will be left in the volume of mash liquor that remains in the tun after it's drained. The more you dilute that mash liquor (i.e., the more you sparge) the less sugar will be left in the tun. This is the reason that you tend to get better efficiency for lower gravity beers.

[MakeMeHoppy]

In a normal situation, when you don't oversparge, some sugar will be left in the volume of mash liquor that remains in the tun after it's drained. The more you dilute that mash liquor (i.e., the more you sparge) the less sugar will be left in the tun. This is the reason that you tend to get better efficiency for lower gravity beers.

This essentially was going to be my post to the original question here. Batch sparge makes if easier to prove this point. The most times you sparge the lower the gravity of the wort still left absorbed in the grain and in the dead space of the tun. I think on the same point you'll typically find your efficiency goes down when you make a very high gravity beer. This is because you meet your pre-boil volume with higher gravity wort still in the mash tun.

[Deerslyr]

Apparently I need to go back and re-read Designing Great Beers to see what Daniels has to say on this matter.

[MtnBrewer]

I think on the same point you'll typically find your efficiency goes down when you make a very high gravity beer. This is because you meet your pre-boil volume with higher gravity wort still in the mash tun.

For higher gravity beers, you're sort of up against a double whammy. First of all, the concentration of sugar in the mash liquor is higher. So there is more sugar in whatever mash liquor is left behind. Secondly, since the mash is bigger, you have more mash liquor and thus less water available to sparge with for a given pre-boil volume.

[MakeMeHoppy]

For higher gravity beers, you're sort of up against a double whammy. First of all, the concentration of sugar in the mash liquor is higher. So there is more sugar in whatever mash liquor is left behind. Secondly, since the mash is bigger, you have more mash liquor and thus less water available to sparge with for a given pre-boil volume.

Right and a lot of brewers will then sparge more and collect a much larger pre-boil volume and then boil that down to their standard post volume volume in order to get better efficiency. (Or make a second beer with the extra volume collected)So back to the OP here, a very small volume beer has the opposite effect.

[Malzig]

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

I'm sorry I'm not communicating this as well as I might, but I'm not trying to claim either of these things, so I won't try to defend them. Let me try again to see if I can clarify.I'm simply trying to say that, if you know your beginning volume and your evaporation volume you can calculate a percent boil-off for your system. If two systems happen to achieve the same percent boil-off, for a given target OG there is a predictable efficiency.If I can push my evaporation down a little further to 0.7 gallons on a 3 gallon batch in one kettle, and get your 1.15 gal loss from my 5 gallon kettle, the percent evaporation would be the same. As a result, I could expect the same efficiency from identical OG batches made on both systems. Since I actually boil off slightly more (percent-wise, yet less volume-wise) in my 3 gallon system, I get slightly higher efficiency from my 3 gallon system.

[Malzig]

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.No amount of boiling will change the amount of sugar he has... only the density of the wort.

I'm not sure I entirely understand this, but let me see if I can explain if the subsequent posts haven't done it already...Boil-off has nothing to do with efficiency in that two worts collected at 50% efficiency will not change efficiency if one is boiled down more. But, if two worts ended up at 5 gallons, but one was boiled down more because more wort was collected, the one from which more wort was collected will have a higher efficiency.

Here is the thing I was trying to avoid confessing to. I have oversparged to the point where the gravity reading at 60 degrees of the truly final runnings was zero. I boiled down to my target volume of 6 gallons. My OG was spot on target for what BeerSmith had said I should be at with a Brewhouse Efficiency set at 78%, with 12 pounds of grain for a final volume of 6 gallons. Please explain to me how I left 22% of the sugars in the mash tun?

Fly sparging is a more difficult to model mathematically because you could very well have left sugar behind due to channeling. However, this sounds like you are very much probably not getting 100% conversion. You should check the gravity of your wort before starting your sparge to determine that you've achieved near 100% conversion.While I certainly don't get 100% extraction, since I don't use a mash filter system, I do routinely get 95-100% conversion, at which point it's quite easy to get 83-87% efficiency from the grain bill you describe with final runnings of 1.024 or greater from a simple 2 runnings Batch Sparge system.

[MtnBrewer]

I'm sorry I'm not communicating this as well as I might, but I'm not trying to claim either of these things, so I won't try to defend them. Let me try again to see if I can clarify.I'm simply trying to say that, if you know your beginning volume and your evaporation volume you can calculate a percent boil-off for your system. If two systems happen to achieve the same percent boil-off, for a given target OG there is a predictable efficiency.

That's true but a more useful way to think about it is that if you know your evaporation rate and your final batch size, you can calculate your beginning volume. It would be very unlikely for two systems to have the exact same evaporation rate expressed as a percentage.

If I can push my evaporation down a little further to 0.7 gallons on a 3 gallon batch in one kettle, and get your 1.15 gal loss from my 5 gallon kettle, the percent evaporation would be the same. As a result, I could expect the same efficiency from identical OG batches made on both systems. Since I actually boil off slightly more (percent-wise, yet less volume-wise) in my 3 gallon system, I get slightly higher efficiency from my 3 gallon system.

Another way of saying that is that if you collect proportionately more volume for a larger batch the efficiencies of the two batches would be the same. I think that might be approximately true but efficiency is a function of more than just pre-boil volume.

[Deerslyr]

I'm not sure I entirely understand this, but let me see if I can explain if the subsequent posts haven't done it already...Boil-off has nothing to do with efficiency in that two worts collected at 50% efficiency will not change efficiency if one is boiled down more. But, if two worts ended up at 5 gallons, but one was boiled down more because more wort was collected, the one from which more wort was collected will have a higher efficiency.

So if I over-sparge on two batches, collect 6 gallons on one and 6.5 gallons on the other and then boil them both down to 5 gallons and they end up at the same gravity, I was more efficient on the 6.5 gallon runnings??? During a sparge, the amount of sugar that is absorbing into the liquor decreases on a curve. And at a certain point, any amount of sugar that is coming out is negligible.

Fly sparging is a more difficult to model mathematically because you could very well have left sugar behind due to channeling. However, this sounds like you are very much probably not getting 100% conversion. You should check the gravity of your wort before starting your sparge to determine that you've achieved near 100% conversion.While I certainly don't get 100% extraction, since I don't use a mash filter system, I do routinely get 95-100% conversion, at which point it's quite easy to get 83-87% efficiency from the grain bill you describe with final runnings of 1.024 or greater from a simple 2 runnings Batch Sparge system.

If I check the gravity of first runnings, you still have the same issue in checking your gravity. If I mash 12 pounds of grain at 1.2 quarts per pound (or 3.6 gallons of strike water) and input that into BeerSmith, it still needs an Efficiency Variable. So lets say I put in a factor of 78% (which is where my fly sparge system is) and Beersmith says my Gravity should be 1.095, I take my gravity reading and it comes in right around 1.095, then clearly I have not acheived 100% efficiency. It is clearly something else. I lean towards the poor crush or the fact that I have not acheived full conversion, which means to me that I have left sugars in the tun somewhere that could not come out. The OP doesn't seem to care about this argument and has moved on. I'm going to do the same because we are clearly not going to see eye to eye on this.

[djinkc]

So if I over-sparge on two batches, collect 6 gallons on one and 6.5 gallons on the other and then boil them both down to 5 gallons and they end up at the same gravity, I was more efficient on the 6.5 gallon runnings??? During a sparge, the amount of sugar that is absorbing into the liquor decreases on a curve. And at a certain point, any amount of sugar that is coming out is negligible. If I check the gravity of first runnings, you still have the same issue in checking your gravity. If I mash 12 pounds of grain at 1.2 quarts per pound (or 3.6 gallons of strike water) and input that into BeerSmith, it still needs an Efficiency Variable. So lets say I put in a factor of 78% (which is where my fly sparge system is) and Beersmith says my Gravity should be 1.095, I take my gravity reading and it comes in right around 1.095, then clearly I have not acheived 100% efficiency. It is clearly something else. I lean towards the poor crush or the fact that I have not acheived full conversion, which means to me that I have left sugars in the tun somewhere that could not come out. The OP doesn't seem to care about this argument and has moved on. I'm going to do the same because we are clearly not going to see eye to eye on this.

I would say that the 6 gallon runnings was more efficient but efficiency would be the same. Same amount of sugar with less sparge water. I don't use BS but I would assume it's similar to tastybrew's calculator. If you put in 78% and get 1.095 as predicted, then you had 78% efficiency - assuming this is what you calculated for final volume of the runnings.You're always going to leave some sugar in the tun unless you collect 10 gallons for a 1.030 beer boiled down to 3 gallons..... Efficiency is fun to talk about but hitting your gravity in the fermenter is what you want.

Edited by djinkc, 17 August 2010 - 04:53 PM.

[Malzig]

That's true but a more useful way to think about it is that if you know your evaporation rate and your final batch size, you can calculate your beginning volume. It would be very unlikely for two systems to have the exact same evaporation rate expressed as a percentage.Another way of saying that is that if you collect proportionately more volume for a larger batch the efficiencies of the two batches would be the same. I think that might be approximately true but efficiency is a function of more than just pre-boil volume.

Maybe that's where we're crossing wires. I wasn't trying to supply a way to determine final batch size. I was trying to explain why efficiency increases with more boil-off, that reason being larger sparge volume.

I would say that the 6 gallon runnings was more efficient but efficiency would be the same. Same amount of sugar with less sparge water. I don't use BS but I would assume it's similar to tastybrew's calculator. If you put in 78% and get 1.095 as predicted, then you had 78% efficiency - assuming this is what you calculated for final volume of the runnings.You're always going to leave some sugar in the tun unless you collect 10 gallons for a 1.030 beer boiled down to 3 gallons..... Efficiency is fun to talk about but hitting your gravity in the fermenter is what you want.

I didn't actually consider this an argument, just an explanation. It certainly never occurred to me that I would have to defend the concept that increasing sparge volume increases efficiency! It's pretty common that brewers wanting to brew high gravity beers will sparge more and boil longer to improve their efficiency.If you fly sparge with 6 gallons to something greater than 1.000, then yes, your efficiency will increase if you increase the sparge volume to 6.5 gal because the first drop of water after 6 gallons will contain some amount of sugar. That's pretty much the definition of efficiency, getting more sugar from the same amount of mash.The original question involved a Batch Sparge, though, and that's what I was primarily addressing. In a Batch Sparge the effect is more clearly defined since it isn't affected by channeling and second running gravity is nearly impossible to get as treacherously low as can happen in a fly sparge, and certainly with severe channeling or a running gravity of 1.000 increasing volume will not increase efficiency. On the other hand, increasing sparge volume will always increase efficiency in a Batch Sparge.It does look like you have a channeling or conversion problem, though, if you are hitting 1.000 by 6 gallons and only achieving 78% efficiency. Poor COnversion Efficiency can easily lead to oversparging, as you may have seen. Unfortunately, Beersmith can't easily help you determine your Conversion Efficiency. There is, however, a predictable gravity of First Wort that is easily determined from mash thickness. When you want to drain your first runnings you cross reference your mash thickness in a chart like (from Kai Troester's site) this to find what the gravity should be at 100% conversion:I strongly recommend reading thison Kai Troester's site to get a thorough explanation of the factors effecting efficiency from someone who has studied the subject thoroughly.

[MtnBrewer]

Maybe that's where we're crossing wires. I wasn't trying to supply a way to determine final batch size. I was trying to explain why efficiency increases with more boil-off, that reason being larger sparge volume.

We're actually in agreement about that. I was trying to explain it in a way that didn't involve evaporation rate because I think it just confuses the issue. The real issue is pre-boil volume. Also I wasn't trying to supply a way to determine final batch size either. Batch size is not something you calculate, it's something you use to calculate something else. It's an input to the process.

[MtnBrewer]

So if I over-sparge on two batches, collect 6 gallons on one and 6.5 gallons on the other and then boil them both down to 5 gallons and they end up at the same gravity, I was more efficient on the 6.5 gallon runnings???

Two batches with the same grain bill that come out to the same volume and same gravity have the same efficiency.

If I check the gravity of first runnings, you still have the same issue in checking your gravity. If I mash 12 pounds of grain at 1.2 quarts per pound (or 3.6 gallons of strike water) and input that into BeerSmith, it still needs an Efficiency Variable. So lets say I put in a factor of 78% (which is where my fly sparge system is) and Beersmith says my Gravity should be 1.095, I take my gravity reading and it comes in right around 1.095, then clearly I have not acheived 100% efficiency. It is clearly something else.

It is 78%. As I said earlier, you won't achieve 100% efficiency unless you do a congress mash, which of course is not practical for brewing. It is only a laboratory reference.

[Malzig]

We're actually in agreement about that. I was trying to explain it in a way that didn't involve evaporation rate because I think it just confuses the issue.

I'm pretty sure we were trying to say much of the same thing, from two different directions. For clarification, however, I never meant to bring evaporation rate into the discussion. I was discussing evaporation volume; increased evaporation volume being one way to connect sparge volume to efficiency. You can do the math using either actual volumes for batch size and sparge volume, but the one value that is independent of batch size is evaporation % (not %hr), only because the batch size is included in the percent evaporation calculation. That is not to say that your evaporation percent will not be greater with a smaller batch; it will unless you boil longer.

It is 78%. As I said earlier, you won't achieve 100% efficiency unless you do a congress mash, which of course is not practical for brewing. It is only a laboratory reference.

One thing to remember is that a mash is virtually a congress mash, until it's drained. With good techniques it's entirely possible to achieve 100% efficiency within the tun (e.g. Conversion Efficiency). Subsequent losses are due to the inefficiencies inherent in lautering by dilution, of course, which is where the sparge volume comes into play and why breweries like Alaskan Brewing Company come close to 100% Mash Efficiency by using a mash filter system to leave the grain virtually dry.