Mashing with RIMS - Efficiency Issues

[brandonnys]

I'm trying to figure out where an issue might be with our mashing process. Perhaps someone can shed some light on what we may be doing wrong here.

5.50Gal Batch Size

Malts
10# 2-Row
2# C40
1# C80
Some 5.2pH Stabilizer (according to instructions)
Water (Washington County, OR Municipal - http://jwcwater.org/water-quality/home-brewing-info/)

PROCESS

1. Heat 24qt water in HLT to to 156F.
2. Pump water into mash tun.
3. Turn on RIMS system, recirculate at 156F to level out the temperature.
4. Add all grains in, stirring well. (Temp in the tun drops to 145F at this point).
5. Set temp at 145F on the PID. Pump through RIMS tube for 30 minutes.
6. Raise temperature to 155F over 10 minutes, leave there for 60 minutes.
7. Raise temperature to 170F over 20 minutes, leave there for 10 minutes.

When we start the temp step from 7, we start up 12qt water to 170F in the HLT.

8. Pump wort from mash tun into brew kettle.
9. Gravity-feed water from the HLT over the grain bed, continue to pump out into BK.
10. Once pump no longer pumps, take sample readings and begin boil.

Using the process above on two identical recipes the same day:

BATCH 1
Est. Pre-boil Vol - 7.13gal
Measured - 7.20gal
Est. Pre-boil Gravity - 1.049
Measured - 1.046

BATCH 2
Est. Pre-boil Vol - 7.13gal
Measured - 7.10gal
Est. Pre-boil Gravity - 1.049
Measured - 1.044

Does anyone have any ideas? Please ask for more info if needed, I'll supply whatever you need.

Thanks in advance, everyone!

 

[doug293cz]

If I understand your process, you are fly sparging with a fixed amount of water, and completely draining the mash tun after adding all of the sparge water. Is this correct?

The following comments are based on your process being as described above. If it is different, then not everything below will apply.

Typical grain absorption rates for a fully drained MLT are about 0.12 gal/lb, so with 13 lbs of grain, you should expect your collected wort to be 13 lb * 0.12 gal/lb = 1.56 gal less than your total brewing water. You used 9 gal of brewing water, and collected an average of 7.15 gal of wort, so your average volume loss was 1.85 gal, or about 0.3 gal more than expected. This could be due to undrainable volume in your MLT, which will have a negative effect on your lauter efficiency. Anything you can do to reduce the undrainable volume will help your efficiency.

When fly sparging, you want to maximize the volume of water used for sparging, so you should mash with less water. Many brewers use 1.25 qt/lb for mashing, which in your case would be 1.25 qt/lb * 13 lb = 16.25 qt. This would leave you 7.75 qt more to sparge with. You mashed at 24 qt / 13 lb = 1.85 qt/lb.

Your first runnings wort should have had an SG of 1.067 - 1.068 if you got 100% conversion efficiency, and your pre-boil gravity would have been about 1.055. Did you happen to measure first runnings SG? If so, we could calculate your conversion efficiency. Given the simulated values, I suspect your conversion efficiency may have been as low as 81%, which is pretty bad. I recommend you monitor your SG during mashing to tell when conversion is complete. Compare your mash SG to the table here to tell if conversion is complete.

You don't say anything about your sparging rate. If it was too fast, you could have gotten channeling in the grain bed, which kills the efficiency of the sparge. A fly sparge for a "5" gal batch should take a minimum of about 30 minutes, but 45 minutes would be better.

As far as the sparge process, you should first drain the MLT until about 1" of wort remains above the grain bed before starting to add sparge water. Initial draining can be faster than the sparge drain rate.

Brew on

 

[Bobby_M]

I have to ask why you are mashing for almost two hours. Between that and a slow fly sparge, you must be spending 7 hours brewing. Even if you want to play with step mashing, those rest times are outrageous. The mash out doesn't need to be held for 10 minutes. Just start sparging when you reach 170f.

Keep the grain bed fully wet during sparge with 1 to 2 inches over the grain. You should also not run the bed dry at the end. When batch sparging you calculate for no leftover wort in the tun but with fly sparging you should have a couple gallons left when you stop collecting to keep the grain bed from collapsing.

With such a long mash schedule recirculating for the whole time, you may have created very distinct channels though the bed. Stirring the mash well right before the mash out ramp would help a lot.

Two unrelated comments. 5.2 product sucks. 3 pounds of caramalts in 13 pound bill is a little heavy handed.

 

[blizz81]

I have to ask why you are mashing for almost two hours. Between that and a slow fly sparge

Is it slow though? It sounds like they're using the pump during the fly sparge to evacuate into the boil kettle?


If that's correct, I'd think if you wanted to fly sparge, you'd want to just let the wort drain into the boil kettle at a controlled rate...probably not even full-bore open on a valve, from what I understand about fly sparging.


I agree on step / mash time(s). If you're letting your mash sit at 145*F for 30 min, you're getting a lot of conversion at a pretty low mash temp. I imagine it may be difficult to make anything other than over-attenuating / dry beer this way (maybe intended). Also agree on channeling - how is the return on your setup? Do you notice channeling in the grain bed?


On batch 1, you were over-volume, so pretty close to whatever number you have as est. Don't know why batch 2 would be so different if you were using identical source material / identical process.

 

[brandonnys]

We're using a SS basket that we fabricated to fit inside a Coleman 70-qt Cooler.It has legs on the bottom that give us about a half inch of space between the bottom of the basket and the bottom of the cooler. The basket has a perforated SS bottom, so the grain settles and drains out into the cooler. Then there's a bazooka tube at the bottom that goes through a bulkhead, out through the valve to the pump/RIMS tube. Then it comes back into the cooler through a bulkhead, and is spread evenly over the grain bed using pipes with very small diameter holes drilled in it, facing up.

We came up with this solution because we were having issues with the grain clogging up the bazooka tube when we turned on the pump to start circulating through the RIMS.

The idea behind the short/low step and the long/high step was to give the enzymes ample time to convert in their ideal range. We wanted to extract a decent amount of fermentables, and then move up to the higher temperature to extract a combination of fermentables and nonfermentables. If this doesn't make any sense, I'm totally open to suggestions here.

With these last two batches, tunneling wasn't an issue during mash because we had so much water in the mash tun, but you could see that slight tunneling during the sparge. The reason we have so much water allocated to the mash was to keep the grain bed completely submerged during the mash, and with the numbers you recommended and our equipment with its current configuration, complete coverage isn't possible, so we adjusted up.

As for the first runnings gravity, I did not take this reading. I will be more diligent about taking this down on the next batch this weekend.

I think this is probably a key we've been missing:

Keep the grain bed fully wet during sparge with 1 to 2 inches over the grain. You should also not run the bed dry at the end. When batch sparging you calculate for no leftover wort in the tun but with fly sparging you should have a couple gallons left when you stop collecting to keep the grain bed from collapsing.

Is there a target gravity that we'd be looking for here?

Our process does take an incredibly long amount of time. Two batches back-to-back takes almost 12 hours.

Noted on the 5.2 product. I didn't really notice any difference in efficiency once we introduced it, and our municipal water is pretty brew-friendly.

Also noted on the heavy-handedness. This bill produced a very malty copper IPA, much too sweet. I already re-wrote the recipe to back those values way off.

Thanks for your help, guys.

 

[Bobby_M]

With a basket that has exits on the sides as well as the bottom, you should not be fly sparging it at all. I'm almost positive this is your problem. If it were me:

Single temp rest, dough in with the water at 163 or so and then target 152 on the RIMS. After the 60 minute rest run the wort out to the kettle IN FULL. Add full amount of sparge water, stir like hell, recirculate again for 2 minutes to vorlauf and do another full drain to the kettle.

Your brew day will be shorter and you will probably see a 10% efficiency gain.

 

[brandonnys]

The basket does not have evacuations on the sides. It only has a perforated bottom. It's custom made, not like a crab basket.

 

[Bobby_M]

Ok, fair enough. Posting a picture of the crushed grain may help also.

 

[brandonnys]

Sorry, I re-read my response and it sounded a bit snarky. Not my intention.

So, funny you should mention a picture of the grain, because I thought about that too. I went back and looked at our pictures (we try to catalogue all of our brew days with pictures during the process) and the grain doesn't appear to have been cracked all that well. See below.

 

[blizz81]

I would normally look to crush, but in this case I would think recirculation + that super long mash time should allow for you to have a pretty darn coarse crush. There was a thread ( https://www.homebrewtalk.com/showthread.php?t=543873 ) not too long ago that among other things, covered recirculating brewers experiencing efficiency gains by going to a more coarse crush (some up to 0.040-0.055"). I've widened my gap from 0.028" to 0.0385" and if anything, have noticed a 1-2% jump in efficiency, though I only measure brewhouse eff.

 

[brandonnys]

Do I even need to concern myself with pre-measuring the water I'm sparging with, or can I just sparge until I hit boil volume and go?

 

[doug293cz]

Do I even need to concern myself with pre-measuring the water I'm sparging with, or can I just sparge until I hit boil volume and go?

That's how most fly spargers do it.

Brew on

 

[dyqik]

Noted on the 5.2 product. I didn't really notice any difference in efficiency once we introduced it, and our municipal water is pretty brew-friendly.

Your water is brew friendly, in that it's almost mineral free, and so is neutral base to work from, not that far from RO water. You still need to work on hitting your mash pH though, and 5.2 stabilizer likely won't do it in mineral free water. Your mash pH may be off somewhat. Have a read of Martin Brungard's Working With Low Alkalinity Water thread in the brew science section.

I've done a quick calculation of your mash pH in Brewer's Friend, minus the 5.2 stabilizer - you can view it at http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/?id=0NX94XX

That indicates a mash pH of 5.7, and a need for 3.10 ml of 88% lactic acid to bring the mash pH to 5.4, or 4.75ml to hit pH 5.3.

While I doubt that this is the whole reason for the inefficiency (the sparge issues seem a likely culprit), it may be part of it.

 

[brandonnys]

I'm not following your numbers. I can't see where they are on the page you linked. Can you help me see where those numbers are at?

**edit: Nevermind. I figured it out. **

 

[VladOfTrub]

"The idea behind the short/low step and the long/high step was to give the enzymes ample time to convert in their ideal range. We wanted to extract a decent amount of fermentables, and then move up to the higher temperature to extract a combination of fermentables and nonfermentables. If this doesn't make any sense, I'm totally open to suggestions here."

The only fermenables that Alpha releases is glucose. Here's what takes place. Saccharification occurs within 20 minutes. Saccharification time is indicated on a malt data sheet along with the pH of the malt which is usually 5.8/5.9 with distilled water. Saccharification and conversion are not one and the same. Conversion takes place after Alpha, a prolific and powerful enzyme, liquefies the simple starch chain called amylose at what is known as a 1-4 link. When the chain is liquefied at a 1-4 link, two chains are created, one chain is called the reducing end and the other chain is called the non-reducing end. The non-reducing end is the native sugar in starch, called glucose. The reducing end is comprised of more 1-4 links which Alpha continues to liquefy until there are no longer any 1-4 links left and what is left is non-fermentable sugar and randomly, A-Limit dextrin. Conversion takes place during the maltose rest. Beta converts native sugar, glucose, into maltose which is a di-saccharide and which ferments at a different rate than glucose. Due to the rate of fermentation of maltose a secondary fermenter is needed. When iodine is used it cannot differentiate between saccharification and conversion, it only indicates if starch is or isn't present. Be careful with using large amounts of crystal, the malt is near rancidity and it can have a negative impact on head retention due to fatty acid, regardless of what home brew books say it does. Crystal pH is quite low and it can affect mash pH. Stay away from 5.2 and use sour malt to reduce pH. If you are trying to gain body in the beer, it comes from A and B-Limit dextrin derived from complex starch called amylo-pectin. The temperatures used in the method were not close to the temperature at which amylo-pectin bursts, except at the end when it was too late. Although, Limit dextrin is non-fermentable it is not to be confused with non-fermentable sugar created from simple starch. One is tasteless, the other is sweet. Dextrinization occurs at 149F. Dough in at 95F and adjust pH to 5.5. Remove a portion of the mash and step it from 95F to 122-125F and rest it for 20 minutes and raise the temperature to 155F and rest it for 20 minutes and then use iodine. If the iodine isn't reddish/mahogany continue to rest the mash for another 10 minutes. If iodine remains blue/black, not to worry. Then, boil the decoction for at least 20 minutes. Skim off hot break as it occurs or boil longer for hot break to form. If all the ducks line up, a longer boiling period forms mellanoidin. Use the RIM to maintain the main mash at 95F. Enzymatic action will be slow in the main mash which allows the decoction to be screwed with for a long period of time. Boiling the decoction will burst amylo-pectin and reduce protein gum. Enzymes will form Limit dextrin from amylo-pectin now in solution, during the higher temperature rest periods. Use the decoction to raise the main mash from 95F to 130F and rest it for 20 minutes, saccharification will begin to take place, slowly. During the rest beta glucan will be reduced by proteolytic enzymes, mash viscosity reduces and glucose will form. Reduce pH to 5.2 in the main mash and raise the temperature to 145/148F, conversion rest, and allow the mash to rest for 20 to 30 minutes. Crank up the heat to 152F and rest it for 15 minutes, A/B-Limit dextrin rest and crank up the heat to 162F for a ten minute rest, Alpha-I rest. Use boiling water to reach high temperature if RIM is too slow.Then, fly sparge to 1010.
The crush that was used was poor.