Major premise: Longer boils increase efficiency
Minor premise: Adding 2 gallons of distilled water will increase my boil time
Conclusion: Therefore, adding distilled water increases my efficiency
Longer boils can’t “cause” efficiency, but a particular brewer’s habits can lead to him/her using methods that in turn typically produce higher efficiency.
So the “practice” of wanting to conduct a longer boil requires the running off of more sugar-entrained wort from the mash tun, and it is here – in the running of more water through the mash and it’s collection of more sugars – that the increased efficiency comes from. What “caused” the brewer to make that decision is immaterial where efficiency is concerned.
Of course, there’s another way to put it:
Q: What caused that guy to get more efficiency?
A: He wanted to do a longer boil, so he used more sparge water.
If you use more water to sparge, then you will collect more sugars, but at the cost of having to boil off the extra water. That’s where the efficiency goes down. An example: say we’re brewing a batch with 8 pounds of pale malt which yields 6 gallons of wort at a gravity of 1.036. The yield and gravity is measured before any boiling happens. We calculate the total sugar extraction as 36 points multiplied by 6 gallons equals 216 points. All pale malt has a potential extraction of about 1.036. So in this case, the total potential efficiency would be 36 points multiplied by 8 pounds yielding 288 points. The efficiency is then 216/288 * 100% = 75%.
If you use more water to sparge, then you will certainly get more sugars out of the mash. But the gravity of the wort that is extracted using the extra water (the wort at the end of the sparge) is lower than the gravity of the wort drawn off previously. This would be different for batch sparging, but the gravity of the wort for the second batch would be lower for 3 gallons of batch sparge water than for 2 gallons of batch sparge water. With big beers, this may be less noticeable because you may be using a thicker mash or just more grain and there would therefore be more sugars to be extracted (or less left in the tun). With normal gravity beers, adding additional water will cause the gravity of the wort that is extracted using the extra water to be very low in gravity. In both cases, it depends on what gravity you would normally stop the sparge and how much further you’re willing to take that. Using the example above, if you collect 7 gallons but at a lower gravity of 1.030 the total sugar extraction would only be 210 points instead of 216. It comes down to trying to find the balance between these two factors without letting the pH go too high or letting the gravity of the runoff go too low .
Correcting for (possibly) less efficient mashes by boiling longer does create a beer that may have an equal or even higher OG, but that doesn’t have anything to do with the mash efficiency. However it’s done, it’s about the process that works on a given system and the final product.
jrskjei: thanks, a reasonable argument presented in a civil manner. Glad you’re here.
But I do disagree with a few of its points.
I assume you mean from the same mash, i.e., run off 7 gallons instead of 6.
Question: If you take your example of 6 gallons with 216 points, and add a gallon of pure water to it, you would have 7 gallons of 1.0308 wort…still 216 points. How then can you take the same 6 gallon 216 point wort, add a gallon of water to it by running that water through the lauter tun, and somehow lower the total points to 210?
I’ll agree that there may be limited gain from running additional water through the lauter tun, maybe even zero sugars, but no way it’ll “subtract” from what you already have, and lower the points you’ve already extracted.
I like the page Kai has created on the subject.
His findings, for both batch and fly sparging, support the contention that “The more water that is available for sparging, the more extract can be rinsed from the grain.”
Your logic in the second paragraph does not compute. If I take your original 216 pts for 6 gallons, and dump a gallon of water in to the kettle, you end up with 216/7=1.031 SG (rounded up slightly). If you get your original points in the kettle for 6 gallons and then sparge to collect one more gallon, you will get more points into the kettle than 216. Sure the SG for the larger amount is lower, but you have more points in the kettle. That is what some of us are trying to say.
I see another post has the same point. Had to answer the wife’s questions.
We can talk about mash efficiency and debate the effects of the crush or mash pH. This is important for brewers in the sense of getting the most out of your grain. One must know the exact volume of water and weight of grain added to the mash tun in order to calculate the mash efficiency.
Brewhouse efficiency on the other hand is the brewing process efficiency as a whole including any losses. Losses anywhere in your brewing system, including deadspace in the mash tun, transfer lines, pumps, and trub at the end of the mash result in lost wort. The lost wort takes sugars with it, reducing your overall brewhouse efficiency.
You’re right, I used the numbers in a “for example” manner. I don’t know for sure that adding another gallon would drop the gravity of the wort to 1.030, and when viewed as a total points result, there is no way to subtract points by adding water. The point I was driving at was that when adding water to the calculation (increases efficiency), the lower gravity (decreases efficiency) balances out at some point. And then you have to spend more time and money on propane to get to nearly the same place.
That is a nice piece… I hadn’t seen that before. I was thinking along the lines of what Kai has on page 19 (benefit of additional sparges quickly diminishes…)
Thanks for the discussion. The apples to oranges comparison was at least funny, and who doesn’t like to discuss beer? If we could only keep the wives from interrupting our, um, learning. ;D
I guess I’ll just keep repeating the factual information.
The efficiency is the same pre-boil or post-boil. So the boil has no effect AT ALL on efficiency because sugars are conserved.
Now if you lose some wort in your hoses, that’s your mismanagement, and has nothing to do with the boil. If you have to runoff more wort due to an inadequacy of gravity and have to boil the resultant volume longer, the efficiency of that wort is still the same pre and post boil.
Feel free to not take my word on it. Cool a sample of wort to the proper temp and measure the pre-boil gravity and measure the volume of wort. Repeat post boil (in the kettle). You’ll find the volume x pts equal before and after the boil. You could boil it for a nanosecond or for hours and that will remain true. At some point you might boil off all the water which will make it tricky to measure the gravity, but it still would remain true
If during the mash and resulting run off and sparging I collect 5 gallons of wort that contains 85% of the sugars in the grain then the efficiency is 85%.
If nothing else is done the efficiency is 85%.
If this 5 gallons is boiled for 1 hour and 4 gallons of wort remains the efficiency is 85% - the specific gravity is higher but the efficiency is still 85%.
If it is boiled down to a quart of syrup the efficiency is 85%.
If this syrup is dumped in an Olympic size swimming pool the efficiency is 85%.
Regardless of what happens to the original wort its not going to pull out any more of the 15% of the sugar that was left behind in the grain which is now in the mulch pile.
OK…got it. I agree, there is a point where diminishing returns prompt a brewer to stop sparging or limit the number of batch sparges they run; some base it on time savings, some on cost, some on flavor/stability impact, etc.
You’re giving me flashbacks to college economics – marginal analysis and the decision to produce one more unit of output.
tubercle…that’s it in a nutshell…or is that you in a nutshell? ???
Mikey…any idea what specialty grains would make a brown ale/porter taste like a Baby Ruth? Sounds interesting.
