BIAB Dunk Sparge & BeerSmith

[Black Island Brewer]

I mentioned on another thread that I'm getting ready to brew a wheatwine, and that I am going to try a dunk sparge (for the first time) to increase the efficiency of this wheat-heavy, large grain bill. As I was tinkering with BeerSmith and trying to account for the volume of water I planned to hold back for the dunk, (and after reading a few old threads here that were about trying to adjust the strike volume to account for the amount of the "sparge" volume), I found that by adjusting the "top off" water, BS will adjust the strike volume and temperature accordingly.

I'd love to hear any and all data points on your own results from dunk sparging and efficiency. As I said in that other thread, I'm going to measure the SG of the drained wort, the last squeezings, and the bre-poil gravity after the dunk to see what I can learn.

 

[dmtaylor]

You'll gain a lot of efficiency from a dunk sparge... but with a wheatwine, you still might not break 70-75%, just because it's such an enormous beer style. Treat it like a batch sparge, where you try to get half the volume from the initial mash and half from the sparge. This maximizes efficiency, and might make it easiest for BeerSmith or other software to calculate. You'll find the sparge temperature will most likely be calculated at around 190-195 F, and to use boiling water for the dunk sparge would not be wrong either -- ignore any rules of thumb that say "you'll extract tannins". It ain't true, not for batch sparging.

If you expect no more than 75% brewhouse efficiency, I think your wheatwine will be a success. Maybe even figure only 70%. These values assume a really tight milling of the grains. If your LHBS is crushing the grains for you, then you're more likely to max out around 65%. Don't say I didn't warn you. And good luck! (I haven't read your "other thread" so forgive me if I've answered questions not applicable to your situation.)

Cheers.

 

[Sadu]

I got 78% on a RIS using biab with a single dunk sparge, as others have suggested I was expecting it to be worse. To save time I mashed overnight, not sure if that helped or not. Even after getting that I was getting 1.040 wort out of the spent grains. So I took an extra gallon or so for starters.

 

[RM-MN]

I got 78% on a RIS using biab with a single dunk sparge, as others have suggested I was expecting it to be worse. To save time I mashed overnight, not sure if that helped or not. Even after getting that I was getting 1.040 wort out of the spent grains. So I took an extra gallon or so for starters.

Longer mashing can help a lot if your grains aren't milled fine enough. It gives time for the starches inside the grain particles to gelatinize and be converted. The enzymes are denatured fairly quickly at mash temps so the conversion does not continue all night.

A batch sparge will rinse out more sugars and a double batch sparge will get more yet but continuing to sparge after that is pretty much a waste.

 

[Black Island Brewer]

I'll be happy to add my data to these observations. Regarding milling, using the ugly junk corona mill cranked down as tight as it will go, I nearly get flour. One of my favorite mashing schedules is to dough in, head off to a meeting I go to weekly, then come back 2.5 - 3 hours later, suspend the bag, drain, squeeze and boil. I've had anywhere from 85 to 95% conversion doing this, assuming that the expected yields are accurate. But, when I chew on the spent grains, I can still taste sugar, some batches more than other, correlating pretty well with the measured efficiency.

I'll post results when I have them.

 

[Black Island Brewer]

In the end, with a dunk into 2 gallons of sparge water, I ended up with 73.3% mash efficiency. I think next time on a beer this big I may try half and half WRT the sparge volume.

 

[toxdoc49]

I too have become a fan of dunk sparging. I don't have a grain mill so I have to get my grains already crushed; it doesn't seem to be a problem (yet). I follow the mash schedule, then mash out at about 170 degrees F for 10 minutes. Then raise the bag (I do BIAB as well) and squeeze it (I see various methods for that and appreciate others' insights into that on this site). Then I will dunk sparge in the appropriate volume of water (also at about 170 degrees) for 10 minutes and add that volume to my kettle pre-boil. One can always do the dunk sparging necessary to achieve boil volume. I am still learning so I have not calculated efficiencies with this method, but I do hit my OG targets, sometimes go over. But a little extra fermentable alcohol hasn't bothered me (yet).

 

[RufusBrewer]

If you want to increase OG, collect more wort preboil. Then do a long, long boil.

The greater the volume collected during the mash, the higher mash extraction efficiency. The longer boil will increase your OG.

 

[toxdoc49]

If you want to increase OG, collect more wort preboil. Then do a long, long boil.

The greater the volume collected during the mash, the higher mash extraction efficiency. The longer boil will increase your OG.

thanks. Then I would just increase pre-boil volume to do a longer boil to get the right amount of volume post-boil. Do you suggest a time longer than the usual 60 minute boil?

 

[RufusBrewer]

The higher volume wort post sparge will increase your mash efficiency.

Can can boil the excess wort to evaporate water out of yoru wort and increase the OG.

Maybe boil do 120 minutes and start adding your hops at the 60 minute mark. The purpose of the first 60 minutes is to concentrate the sugar in your wort and up the gravity.

The trade off is more time and using more energy. But if you want to make a bigger beer and your rig is imposing some limits, this is a method to improve the situation.

 

[Beermeister32]

Dunk sparge works great. Personally I’ve moved away from hot sparges, I run a room temp sparge now. I ran one too hot once and it extracted tannins which makes the beer phenolic tasting.

My dunk sparges are easy as I use a double brew in a bag method, you can dunk easily half full bags in a 5 gallon bucket.

 

[toxdoc49]

Thanks, and thanks for the picture. I've read about 'cold'sparging; I suppose if the mashout is complete it may not matter, only that possibly more sugars are extracted from a hot sparge. But not heating water for a sparge is certainly a time saver. Can you describe some more the double BIAB you have pictured? It looks like two separate compartments.

 

[Beermeister32]

It is. I have 1/8” stainless welding rod bent at the end on itself so there are two lengths of the rod basically holding up the bags. I bent down the tips on a bench vise.

I use two 24”x24” bags and split the grist into each. So if you are running 12 lbs of grain, you dump about 6 lbs in each bag. Not really compartments, just two bags hanging there.

 

[toxdoc49]

Interesting, thanks. I am guessing that it helps a good deal with the sparge step, especially with a big grain bill.

 

[Beermeister32]

Saves your back too. Also no block and tackle pulleys to deal with.

 

[doug293cz]

Thanks, and thanks for the picture. I've read about 'cold'sparging; I suppose if the mashout is complete it may not matter, only that possibly more sugars are extracted from a hot sparge. But not heating water for a sparge is certainly a time saver. Can you describe some more the double BIAB you have pictured? It looks like two separate compartments.

Hot sparge does not extract any more sugar than cold sparge, unless conversion was not complete at the end of your mash, before initial run off. If conversion is incomplete, the proper response is to crush finer and/or mash longer. Measure your conversion efficiency using the method here, and if you want to do calculations yourself, the math is detailed here (in an easier to understand form than Braukaiser's write up.)

Brew on