Stuck on efficiency

[fatom99]

What temp do you mash out at? 170 degree sparge water seems low, since you want to raise the mash temp 168 degrees. I heat my sparge water to 178 to bring my mash temp to 168; of course the sparge water temperature is dependent on the sparge water volume and the mash temp.

 

[doug293cz]

Well its been a while...and several brews. I brewed with a couple friends (fly sparging, 3 keggles) and hit 86% with one and 78% with another.

After all the info from the last few brews, today was the big test. Thermometer was off, profile was off. Fixed them both. Yet today we brewed 63%.

My temps were right on, we stirred the hell out of it (still with a spoon), and batch sparged. Ended up with a little more wort than beersmith called for (1 qt), so I boiled an extra 15 minutes and burned it off.

The grain bill was 14 lb 2row, 1.5 lb crystal 30. I started with 5.5 gallons, drained 3.75 out of that. Added 4.5 more for the batch sparge, drained 4.25 out of that. My brew buddy who knows much more than I do came over and went over everything with me. Measuring temps in different part of mash, everything. And he was shocked.

Why why why?

Put a couple of gallons of water in your MLT, and then drain exactly the same way you do when running off wort. Then dump the water remaining in the MLT after draining into a measuring cup large enough to hold it all. How much water was left in the MLT? This is your MLT dead volume. A high dead volume can adversely affect your mash efficiency (actually the lautering efficiency.) You want the MLT dead volume to be a close to 0 as possible.

You can also measure the SG of your first runnings, and then multiply the SG points [ (SG-1) * 1000 ] times the strike volume you used in gallons. This number should be close to 558 (which should be close to the total potential points of your grain bill.) If it's significantly lower, then you have a problem with your conversion efficiency (not converting the max amount of starch to sugar.)

Mash efficiency = conversion efficiency * lauter efficiency.

Brew on

 

[estricklin]

First off, get yourself a GOOD false bottom. Buy one, or make one from an aluminum pizza pan or a stainless steel element cover for an electric stove. I just read through and I think I read that you have a stainless braid? Batch sparging helps to overcome having a poor false bottom, but I believe that a few bucks on a good false bottom is money WELL spent in homebrewing.

You've been suspecting sparging slower makes a difference, so slow down even more! I have both batch and fly sparged over the years, and I find that sparging too fast in either setup causes my efficiency to suffer, although it's more so in the fly sparging.

Something no one has mentioned much, is your evaporation rate. How can that possibly have an effect on extracted sugars/starches from the mash? Simple, the more water you use, the more sugars you'll extract. Beersmith calculates everything based on the amount of wort you want when the flame is out. Obviously this may not be something you can change, or can change easily; but I mentioned it on the off chance that you might be boiling at a low rate, as in your wort is just barely boiling.

Some things that have been mentioned but I will reiterate, make sure your sparge water temperature is in that 170-175 range, a higher temperature will help the sugars/starches to dissolve easier. Be sure to calculate your volumes as accurately as you can. Crush finer....hell crush til your scared!

Do not confuse starch conversion and sugar/starch extraction. The hydrometer doesn't discriminate, it measures sugars AND starches, so if your mash conversion wasn't complete it won't matter as far as extraction goes, and THAT is what we're really talking about here. Mash pH, temperature, and recipe have virtually no effect on your extraction.

To sum it up really; I bet ya 2 crawdeads and a dollar if you crush finer and sparge slower, you'll be happy with the result!

 

[jdecker1978]

Thanks everyone.

My preboil gravity was 1.050. One thing I know we screwed up was the sparge temp. Beer smith just said 168, and I thought that meant 168 degree water to bring the mash back to 152, where I mash. I know now this means bring it back up to 168. I don't know the batch running OG, I combine them right away with the original runoff, getting me the 1.050.
Another error I made was when I originally calculated my dead space, I didn't account for the grain. When there is grain in the bottom of my cooler, pretty much all of the wort drains out. This means I mashed with too much water.
I don't want to use a false bottom if I don't have to. Everything I'm basically doing is the dennybrew concept. I have pretty much the exact same tun as him, and he brews mid 80% regularly. An interesting thing is he suggests draining the tun wide open. He says from his initial mash drain to the end of the sparge drain is 15 min max.
I will crush finer next time. With the adjustment in dead space, my sparge will be much close to half of the total runnings, which it seems is what I want. I'll give it another run next week and see how it goes.
Thanks again.

 

[doug293cz]

You don't have to sparge with hot water. Kai did an experiment comparing hot and cold sparge water (http://braukaiser.com/blog/blog/2009/05/12/cold-water-sparging/), and found the efficiencies were the same within experimental error. You can also drain the wort as fast as your MLT will allow when batch sparging. Once the sugar is fully dissolved in the wort, running off slower won't dissolve any more sugar as the wort and grains are in equilibrium. If your mash is long enough, the sugar will be in equilibrium. If you mash is not long enough, then you are not in equilibrium (and conversion may not be complete either), and in that case longer run off times can help more sugar dissolve.

A lot of the processes during the mash are controlled by diffusion: water into the grain, sugar and soluble starch out of the grain, etc. Smaller grain particles provide for shorter diffusion distances, so things happen faster. This can improve your conversion efficiency for a fixed mash time, and even allow a shorter mash with good conversion if the crush is fine enough. With very large particles, the diffusion processes may not complete before the end of the mash, in which case your efficiency will suffer.

Brew on

 

[jdecker1978]

I only batch sparge. Its odd because if the sparge temp doesn't matter, then I'm brewing low 60%'s strictly because of small miscalculation with dead space, and grain crush? That seems odd because we crush the grain the same when brewing on my friends rig and get 78-79% (though we fly sparge with his setup). Not saying your wrong, just seems odd.

 

[jdecker1978]

I forgot to mention estricklin I boil pretty hard.

I really want to thank all of you again for chiming in. But you must understand how frustrating this is. I've brewed a ton of beer. I just never cared before. Now that I want consistency this is driving me nuts. Its really hard with the brewing community constantly telling me the opposite of the last guy. One of you says sparge temp is very important, one says its not.
I think my next step is following denny's system exactly, seeing as he has the identical tun and sweats by it. I WILL crush finer next time as well.
At least all the beer I make in my trials still tastes awesome. Probably nearing 50 batches and they've all been incredibly delicious. And thats all that really matters(well that and having fun brewing!).

 

[doug293cz]

I really want to thank all of you again for chiming in. But you must understand how frustrating this is. I've brewed a ton of beer. I just never cared before. Now that I want consistency this is driving me nuts. Its really hard with the brewing community constantly telling me the opposite of the last guy. One of you says sparge temp is very important, one says its not.

I understand your frustration. There is a lot of conflicting information out there. I chose to believe the results of documented experiments, where I have a pretty good understanding of what was done, and the limitations of the experiment. I also choose to believe that which is consistent with fundamental scientific principles (as I understand them.) You have to decide for yourself what information you trust. If you can find a few people with demonstrated knowledge and consistent correctness, that can make your brewing life simpler. Good luck.

Brew on

 

[billl]

You don't have to sparge with hot water. Kai did an experiment comparing hot and cold sparge water (http://braukaiser.com/blog/blog/2009/05/12/cold-water-sparging/), and found the efficiencies were the same within experimental error. You can also drain the wort as fast as your MLT will allow when batch sparging. Once the sugar is fully dissolved in the wort, running off slower won't dissolve any more sugar as the wort and grains are in equilibrium. If your mash is long enough, the sugar will be in equilibrium. If you mash is not long enough, then you are not in equilibrium (and conversion may not be complete either), and in that case longer run off times can help more sugar dissolve.

A lot of the processes during the mash are controlled by diffusion: water into the grain, sugar and soluble starch out of the grain, etc. Smaller grain particles provide for shorter diffusion distances, so things happen faster. This can improve your conversion efficiency for a fixed mash time, and even allow a shorter mash with good conversion if the crush is fine enough. With very large particles, the diffusion processes may not complete before the end of the mash, in which case your efficiency will suffer.

Brew on

Just a note on the numbers there. The "hot" sparge went from 98% conversion efficiency to 89% into the kettle. 9% of the sugar was left in the mash tun. The "cold" sparge went from 99% to 86% into the kettle. 13% of the sugar was left in the mash tun. I don't know what the total error margin was in that experiment, but a variance of 4% is larger than most of us see from batch to batch.

 

[doug293cz]

Just a note on the numbers there. The "hot" sparge went from 98% conversion efficiency to 89% into the kettle. 9% of the sugar was left in the mash tun. The "cold" sparge went from 99% to 86% into the kettle. 13% of the sugar was left in the mash tun. I don't know what the total error margin was in that experiment, but a variance of 4% is larger than most of us see from batch to batch.

If you look at the numbers closely, there are some inconsistencies, but as I will show later they are not outside the expected measurement errors for this type of experiment.

For the hot water sparge he reports 98% conversion and 89% lauter efficiency.
0.98 * 0.89 = 87.2% mash efficiency. But, he reports a 89% to kettle efficiency, apparently 2% too high.

For the cold water sparge he reports 99% conversion and 88% lauter efficiency.
0.99 * 0.88 = 87.1% mash efficiency. But, he reports a 86% to kettle efficiency, apparently 1% too low. In this case he also reports a post boil efficiency of 88%, but it is not possible for the boil to improve efficiency (pre and post boil efficiencies must be the same unless you spill some wort.)​

Based on the above, I conclude that the two cells are the same w.r.t. efficiency, within the probable measurement accuracy of the experiment.

Let's look at the sensitivity of efficiency calculations to small errors in volume measurement.

If I start with 10 lbs of grain having a potential of 37 points/lb (370 total points), and collect 6.5 gal of 1.050 wort (6.5 * 50 = 325 points), I have an apparent mash efficiency of 325/370 = 0.8784 = 87.84%.

Now, if my wort measurement accuracy is +/- 0.125 gal, then I could measure either 6.375 gal (6.375 * 50 = 318.75 points) for an apparent mash efficiency of 318.75/370 = 86.15%. Or, I could measure 6.625 gal (6.625 * 50 = 331.25 points) for an apparent mash efficiency of 331.25/370 = 89.53%. That gives me a measurement range of over 3% for a 1 cup volume measurement error out of 6.5 gal. I don't think most brewers can measure volumes that closely. Therefore, I find no unexpected inconsistencies in Kai's numbers.

Now, think about the fact that there are also errors in gravity measurements, grain weight measurements, and grain potential numbers. It's going to be tough measuring efficiency to better than +/- 2% for a homebrewer.

Brew on