Bag squeeze gravity test

[ArcLight]

In theory, pouring water over the mass of grain is going to generally find a few pathways to get through and avoid a lot of others. It's the definition of channeling that people talk about with fly sparging. With 16 pounds of grain, I was able to squeeze out almost a half gallon more than what would drip out naturally and believe me I let it hang there for 15 minutes without a drop.

Bobby, I used to do that, but I find a dunk sparge does even better. Let it drain for 5 minutes, then dunk into a second pot, stir, and pull and gravity drain the bag.
I get a lot of sugar out of the dunk sparge.

 

[pricelessbrewing]

Like I said in a previous post, I usually get an extra quart or two by pressing after letting it drain for awhile. Likely would have gotten some more out if it were hanging instead of sitting in a bucket, but a 15 second press does the work much quicker. I use a pot lid.

 

[Roboutwest]

Hi all, I've been a long time reader and have meant to join in the discussions for a long while now, but life put brewing well into the background over the last few years. So, by way of introduction, I'm a long time home brewer, some time (almost 3 years) craft brewer, now back to brewing only at home. Discussions here, melded with what I picked up working as a brewer have helped me put together a solid BIAB system with keeper and fermenting/conditioning fridge that can operate reliably and repeatably up to the 104 deg F + we get here.

I've been through the different ways of dealing with the bag. At first, no dunk sparge and a bit of squeezing-this made great beer. Then, after putting numbers in software, I was unhappy with the efficiency and moved to sparking with 6L of water. Here's where the problems began. Suddenly, I started getting brews with some harshness or off flavours. These were getting in the way of the hop and malt flavours. They varied in intensity and were less noticeable in stouts, but could (in my picky opinion) ruin a lighter beer, especially the low alcohol ones. I also noticed some improvement after conditioning/clearing.

Anyway, turns out I was creating problems by either over-sparging or getting the pH of the sparge wrong and extracting tannins as I have high pH ground water. I stopped sparging and went back to the squeeze. In a normal gravity beer it cost 4-5% efficiency, but I ended up with beer that was back on point from wort to glass. So BEWARE the badly executed sparge!
Cheers
Rob

 

[TexasWine]

Hi all, I've been a long time reader and have meant to join in the discussions for a long while now, but life put brewing well into the background over the last few years. So, by way of introduction, I'm a long time home brewer, some time (almost 3 years) craft brewer, now back to brewing only at home. Discussions here, melded with what I picked up working as a brewer have helped me put together a solid BIAB system with keeper and fermenting/conditioning fridge that can operate reliably and repeatably up to the 104 deg F + we get here.

I've been through the different ways of dealing with the bag. At first, no dunk sparge and a bit of squeezing-this made great beer. Then, after putting numbers in software, I was unhappy with the efficiency and moved to sparking with 6L of water. Here's where the problems began. Suddenly, I started getting brews with some harshness or off flavours. These were getting in the way of the hop and malt flavours. They varied in intensity and were less noticeable in stouts, but could (in my picky opinion) ruin a lighter beer, especially the low alcohol ones. I also noticed some improvement after conditioning/clearing.

Anyway, turns out I was creating problems by either over-sparging or getting the pH of the sparge wrong and extracting tannins as I have high pH ground water. I stopped sparging and went back to the squeeze. In a normal gravity beer it cost 4-5% efficiency, but I ended up with beer that was back on point from wort to glass. So BEWARE the badly executed sparge!
Cheers
Rob

I assume you were sparging with hot water, right? Could this have been avoided if you would have used room temp water instead? I've read that tannin extraction requires both high pH and high temps.

 

[Roboutwest]

Yes, sparging with 75 degree C water as usual. Hot water usually gets more sugar out. High ph sparge water was something I was always told to avoid at the brewery.

 

[TexasWine]

Concerning the concept that hot water gets more sugar out, you might want to read Kai Troester's write up on cold vs hot sparge. No difference in efficiency was seen in his experiment. Lots of folks on the forum also use, or have used, a cold (room temp) sparge with no ill effects.

http://braukaiser.com/blog/blog/2009/05/12/cold-water-sparging/

Although I wouldn't think 75 C water would cause any tannin issues, it'd be interesting to try something like 65 C sparge water and see if that makes a difference. Might even do a small batch so that you don't waste a bunch of grains if it turns into a dumper.

 

[ArcLight]

I do a dunk sparge with 20-25C (68 - 77 degrees) water. The sugar is no where near the saturation point so you don't need the extra temperature.
In addition the dunk sparge is performed with the remainder of the water.
Ex: you want 12 gallons of wort. Mash with 7.5 and dunk sparge with 4.5
The total water will be the same as if you did a full volume BIAB.
In addition the dunk sparge doesn't last very long, maybe several minutes.
Then raise the bag again and let drip dry.
Having said that - I suppose it's possible to extract tannins.
I haven't tasted any, but I'm not a BCJP certified judge.

 

[doug293cz]

... The sugar is no where near the saturation point so you don't need the extra temperature...

This is absolutely true (I've posted the data in other threads on HBT), especially for second runnings. Hot sparge water might have some benefit in a couple of cases.

1. Your mash conversion was incomplete (not all available starch converted to sugar.) In that case the higher temps can get you a little more conversion, until the high temps denature most of the amylase.
2. You have a coarse crush, in which case higher temps can speed up diffusion of remaining sugar absorbed in the grain particles out into the wort. However, vigorous stirring during a batch sparge is much more effective at that then waiting for still diffusion to get to equilibrium.

Recommendations:

1. crush fine (I use a 0.4 mm roller gap, and some BIAB'ers grind to almost flour,)
2. keep sparge water less than 70°C (so overshoots can't get you into tannin extraction territory, and
3. stir vigorously for at least 5 minutes before running off your sparged wort.

Do this and it won't matter how cool your sparge water temp.

Brew on

 

[Roboutwest]

Well I'll be... it makes perfect sense that cold would work when you put it that way Texas (i.e.. the sugar solution is not near saturated). It always amazes me that there is so much myth busting going on in brewing these days. That's why I love reading the Brulosopher. I was completely floored out by the quality I can get with a full volume mash when all the pros in the orthodoxy were knocking it for various reasons. Now I appreciate its simplicity, which is one reason i'm not too upset to go Wilser's way and K.I.S.S.. That said, I might try a cold sparge for high gravity beers where there is a lot of sugar left in the bag.

 

[OmegaRed]

You are a MANLY man if you can lift 20+ pounds of wet grain with one hand and support it for 5 minutes. :fro:

While I too am a MANLY man and can lift 25 pounds of wet grain, I decided it was easier to use a $6 ratchet hung from a ladder. I'm still a MANLY man, but I watch gravity drain the bag, which I think is easier and more effective than having the bag rest on a paddle or sit in a colander. The bag kind of flops around with a mash paddle doesn't it? Do you put the paddle across teh pot, and use both hands to support the bag?

Because I'm OCD I still do a dunk sparge, despite wilserbrewers best efforts to cure me

That's the thing though, you're not letting gravity drain the bag. You're squeezing the grain with your bag, because you twist the bag, which does a really good job of squeezing (without you having to touch any hot or sticky areas on the bag).

And yes initially I set the paddle across the kettle, and set the bag on it. For lack of a better descriptor, it looks like a nut sack. You decide which one hangs lower. Mine is the left.

 

[ArcLight]

That's the thing though, you're not letting gravity drain the bag. You're squeezing the grain with your bag, because you twist the bag, which does a really good job of squeezing (without you having to touch any hot or sticky areas on the bag).

Don't you have to twist the bag a lot?

How do you get the leverage to do so without holding it, and getting wort all over yourself?

 

[OmegaRed]

Hard to describe without a picture. I'll try to grab one next time I brew.

Pick the thing up and give it a spin like you do a garbage bag. Then once you rest in on the paddle, a nut falls on each side. Then you can continue to twist as much as you nee.d

 

[BigRob]

I usually let my bag hang for 20-30 minutes in a typical ~5kg grain bill, squeezing nets an extra litre of wort (approx 2.2lbs or so) even after the hanging. I personally don't bother anymore, I add an extra bit of grain, tweak my volumes to account for losses. Hanging still has a lower absorbtion than traditional mash tun type setups.

When I'm feeling thrifty, I throw the bag in a second pot with about 6L of water soak it for duration of boil, squeeze the crap out of it, and use the second runnings as starter wort.