Squeezing the Bag

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goforevercrazywithit

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What's the deal here?

I'm putting together my first BIAB cook and I'm hearing over and over about squeezing the bag after it's removed from the mash.

During extract brewing, I had always heard that squeezing the bag was bad for business as it would release a bunch of unwanted tannins into the brewpot.

So what's the verdict? I'm planning up a Cream Ale where the bag will have 6-row barley and some corn from a cereal mash.

To squeeze or not to squeeze? :confused::goat:
 

jimmykx250

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What's the deal here?

I'm putting together my first BIAB cook and I'm hearing over and over about squeezing the bag after it's removed from the mash.

During extract brewing, I had always heard that squeezing the bag was bad for business as it would release a bunch of unwanted tannins into the brewpot.

So what's the verdict? I'm planning up a Cream Ale where the bag will have 6-row barley and some corn from a cereal mash.

To squeeze or not to squeeze? :confused::goat:
Squeeze away brulosophy guy de-bunked that myth too. Ive been squeezing for a couple years now with no off flavors. Your not extracting anything thats not already there.
 
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goforevercrazywithit

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wilserbrewer

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Go ahead and squeeze if you are impatient. I suggest taking the easy route and let gravity do the work by letting the grain bag drain and drip for 20 - 30 minutes as your wort comes to a boil. Leaving the grain bag to hang above the kettle on a ratchet pulley works well, or placing the bag in a bucket with something to elevate it off the bottom will work well.

I have found after a patience testing free drain, there's not much left to be concerned about.
 

casualbrewer

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Letting it hang will work if you have previously accounted for it. If I do this my efficiency is in the upper 60's. When I squeeze my efficiency is generally upper 70's or low 80's. Lots of ways to skin this cat but which one will be most consistent for the op? That's for him to figure out I guess.
 

TomVA

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It would seem to me this "squeeze" controversy could be easily tested. Just drain the bag without squeezing, then place the bag in another pot and squeeze the bejesus out of it. Sample both pots, cool the samples down to room temperature, and taste them side by side. If the squeezing extracted tannins it should be evident in the wort. No need to wait for the finished beer which will have other factors influencing the taste such as alcohol and carbonation that could possibly mask the tannin comparison.

I will be brewing this weekend and will try this experiment. Since wine tasting and drinking has been a hobby of mine for some 40 years I expect I will be able to pick out tannins from the other wort flavors.

TomVA
 

WiscBrewer

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It would seem to me this "squeeze" controversy could be easily tested. Just drain the bag without squeezing, then place the bag in another pot and squeeze the bejesus out of it. Sample both pots, cool the samples down to room temperature, and taste them side by side. If the squeezing extracted tannins it should be evident in the wort. No need to wait for the finished beer which will have other factors influencing the taste such as alcohol and carbonation that could possibly mask the tannin comparison.

I will be brewing this weekend and will try this experiment. Since wine tasting and drinking has been a hobby of mine for some 40 years I expect I will be able to pick out tannins from the other wort flavors.

TomVA

Makes perfect sense to me. I'll be interested to hear what you discover.
 

wilserbrewer

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I'd be interested in an experiment to gauge total wort recovered by just letting the bag drain for 30 minutes vs squeezing like a mad man.

I have a hunch there is not much gained if any squeezing vs a patient drain of say 30 minutes.
 

TheMadKing

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I'd be interested in an experiment to gauge total wort recovered by just letting the bag drain for 30 minutes vs squeezing like a mad man.

I have a hunch there is not much gained if any squeezing vs a patient drain of say 30 minutes.

I actually tested this and the answer is "it depends on the bag and the grain bill"

Your bags are by FAR the best gravity drainers and 30 minutes resulted in about 2 cups difference in finished wort volume.

The brew bag after 30 minutes was nearly 0.75 gallons short and required squeezing to get the rest. I suspect the two nylon straps inhibit drainage.

A paint strainer bag was about halfway in between.

I also found that the "squeezed wort" seemed to have a higher concentration of sugars than gravity drained wort. I didn't test this for repeatability though. My theory for this is that, like a sponge holding salt after a saltwater dip, grain will always retain some sugars under the weight of gravity. So squeezing liberates water faster and more sugar stays in solution due to the higher volume of water coming out.

The efficiency difference was about 6% on my system.

So I do attribute a small lautering efficiency increase to squeezing, I'll usually do a combination of hanging for about 20 minutes then squeezing the rest out.

Grain bills with oats or flaked adjuncts retain water like crazy and really do need to be squeezed.

The old astringency issue is a non issue. It just doesn't happen. Astringency is the result of a high ph coming into contact with the grain husks, or heating them too much and extracting tannins. Tannins are a water soluble compound under specific conditions (pH and temperature), and are otherwise not soluble.

Saying "squeezing can extract tannins" is the same thing as saying "I can dissolve a bone in my soup if I stir it hard enough"

Sure bone will dissolve but you have to boil it long enough in the correct chemical conditions.

I've squeezed nearly every batch I've ever made in a bag, more than 100, and I've never once experience astringency.
 

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I've also found that squeezing vs hanging depends on the grain bill. Lighter grain bills with less wheat or rye seem to drain fine in the time it takes to get to a boil, but larger ones, and those with higher amounts of wheat or rye seem to take longer to drain, so I squeeze.

I'm putting together a BIAB Wheatwine to brew the Sunday after turkey day (while I also brew a tripel on my 3-vessel system) and I plan to squeeze AND (for the first time) try a dunk-sparge.

When I make the wheatwine, I'm going to check the SG on the wort in the kettle, the wort in the "last squeezings" and the final SG to see what differences, if any, there are.

@jimmykx520, I'd also like the link to the specific xbmt at brulosophy that debunked tannin extraction from squeezing - I could not find any reference to it.
 

TheMadKing

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@jimmykx520, I'd also like the link to the specific xbmt at brulosophy that debunked tannin extraction from squeezing - I could not find any reference to it.

I don't think he ever actually tested that. Brukaiser discusses tannins on his website extensively and talks about how they can be extracted. There's simply no way it can happen from squeezing.. See my post above, that's pretty much a summary of Kai's explanation.
 

Sadu

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I normally sparge in 2 steps, squeezing in between each one. TBH squeezing is one of my least favourite brewing tasks (makes a big mess) but my overall process normally gives me low 80s efficiency and I like that. Would be interesting to know whether squeezing is needed after each sparge or just once at the end.
 

Dimax

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What's the deal here?

I'm putting together my first BIAB cook and I'm hearing over and over about squeezing the bag after it's removed from the mash.

During extract brewing, I had always heard that squeezing the bag was bad for business as it would release a bunch of unwanted tannins into the brewpot.

So what's the verdict? I'm planning up a Cream Ale where the bag will have 6-row barley and some corn from a cereal mash.

To squeeze or not to squeeze? :confused::goat:
I'm a noob at BIAB but to my under standing you have to reach way higher temps than 150 degrees or 170 at a mash out, for any tannin's to develop in your grains?
I would like to know at what temp you are at risk of developing Tannin's
 

Crohnnie

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I'm a noob at BIAB but to my under standing you have to reach way higher temps than 150 degrees or 170 at a mash out, for any tannin's to develop in your grains?
I would like to know at what temp you are at risk of developing Tannin's
Accidentally let my last mash go to 180. Quickly cooled and was only over 150 for ten minutes. What should I expect?
 

wilserbrewer

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Accidentally let my last mash go to 180. Quickly cooled and was only over 150 for ten minutes. What should I expect?

Beer lol. Depnds on when the temp soared to 180. If you mash was at proper temps for a period before that, conversion likely happened quickly. When did the temps soar? You likely only need 10 or 20 minutes to convert most of the starches.

Depending on your PH, the excessive temps MAY HAVE EXTRACTED tannins.

I suggest rdwhahb, what's done is done and your likely ok IMHO.
 

atcsat

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Accidentally let my last mash go to 180. Quickly cooled and was only over 150 for ten minutes. What should I expect?
I once accidentally let mash temp get over 165, but it was after 30 minutes. A couple neighbors thought it was my best brew ever.
 

Black Island Brewer

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I don't think he ever actually tested that. Brukaiser discusses tannins on his website extensively and talks about how they can be extracted. There's simply no way it can happen from squeezing.. See my post above, that's pretty much a summary of Kai's explanation.
Yeah, I know that squeezing doesn't extract tannins - it's a function of temperature, pH and time - but since dude said Marshall debunked it, I just wanted to see the source for myself - too many times folks accept someone's words without actually seeing what backed them up, I don't remember EVER seeing any xBmt about squeezing grains. :mug:
 

Krown

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I usually squeeze until my hands hurts then let it drain over a pasta strainer in a bucket and get up to 2-3 additional litres. Don't forget to increase heat when you add your wort to not kill the boil tho.
 

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I occasionally BIAB at home to test an idea on a 1 gallon setting before running a 1 bbl + batch. After I pull out the bag and let it drain until I get only occasional drips I'll then set the bag in a strainer over a separate small pot while I brings wort up to a boil. By the time my wort is at about 205-210 (just under a boil) I'll have another 6-10 fl oz that drained from the bag on the smaller pot without squeezing and will just dump it into my kettle. Not much fluid but it has helped to balance out gravity and final yields on these little 1 gal batches without extracting tannins
 

TomVA

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So I completed the tannin taste test I described above. I drained the bag over the mash pot without squeezing until it slowed to a drip, then placed the bag in a strainer over a bowl and squeezed the devil out of it, both by pressing it with an inverted bowl and by hand until I couldn't get any more out of it. I then sampled the un-squeezed wort in the mash pot and the squeezed wort in the bowl, cool the samples down to room temperature, and taste them side by side in wine glasses. The squeezed wort was just very slightly darker, sweeter, and more flavorful, but I could not detect any tannins in either sample.

From now on I will squeeze the bag while the wort is heating to boil.

TomVA
 

TooDogly

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I have noticed more fine particulates in the squeezed wort than the non-squeezed. IF your crush was too fine for example and small fragments of husk were squeezed through the bag membrane into your boil then wouldn't tannins be a result of boiling this debris? When gravity draining, the grain acts as a strainer just as it does in a mashtun and you get less cloudy wort. I don't know if this actually has any effect on the flavor of the final beer, but would likely result in more trub after the particulates settle out of suspension.

As far as efficiency goes, I think squeezing results in more sugars being extracted. If you squeeze while the grain is still close to mash temperature then the viscosity of the wort will be lower and you will get more out of the grain. If you allow the bag to drip for a period of time first before squeezing, then the grain will be at a lower temperature and more of the sugars will remain stuck to the grain. Ive done both methods and notice a difference in the spent grain, where the bag that was squeezed while hot has fairly "clean" spent grain, and the drip bag method had more "sticky" spent grain representing sugars still coating the grain.
 

TheMadKing

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I have noticed more fine particulates in the squeezed wort than the non-squeezed. IF your crush was too fine for example and small fragments of husk were squeezed through the bag membrane into your boil then wouldn't tannins be a result of boiling this debris? When gravity draining, the grain acts as a strainer just as it does in a mashtun and you get less cloudy wort. I don't know if this actually has any effect on the flavor of the final beer, but would likely result in more trub after the particulates settle out of suspension.

As far as efficiency goes, I think squeezing results in more sugars being extracted. If you squeeze while the grain is still close to mash temperature then the viscosity of the wort will be lower and you will get more out of the grain. If you allow the bag to drip for a period of time first before squeezing, then the grain will be at a lower temperature and more of the sugars will remain stuck to the grain. Ive done both methods and notice a difference in the spent grain, where the bag that was squeezed while hot has fairly "clean" spent grain, and the drip bag method had more "sticky" spent grain representing sugars still coating the grain.

No offense intended, but There is a lot of misinformation in this post and in this thread in general.

Increased temperature has no effect on lautering efficiency whatsoever. The viscosity of the liquid has zero effect on the amount of sugars extracted. Brukaiser proved this both theoretically and experimentally, and the results are on his website. You can sparge/lauter with room temperature water and be just fine.

As far at the fine crush issue: crushing should not produce small husk particles, unless you are actually grinding your grain to flour. The husks will remain mostly in tact even on a grain mills finest setting, which is where I keep mine. Only the endosperm is being crushed.

If you do get a large amount of husks into your boil kettle then yes you could theoretically get some tannins, but that shouldn't happen unless you've done something wrong with your grain treatment.

The reason your hung bag was stickier than your squeezed bag was that your hung bag had time for wort to evaporate off of it leaving sticky sugar behind, while the squeezed bag was still wet. I bet if you took your squeezed bag and put it in a bucket for 30 minutes it would be just as sticky.
 

Crohnnie

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No offense intended, but There is a lot of misinformation in this post and in this thread in general.

Increased temperature has no effect on lautering efficiency whatsoever. The viscosity of the liquid has zero effect on the amount of sugars extracted. Brukaiser proved this both theoretically and experimentally, and the results are on his website. You can sparge/lauter with room temperature water and be just fine.

As far at the fine crush issue: crushing should not produce small husk particles, unless you are actually grinding your grain to flour. The husks will remain mostly in tact even on a grain mills finest setting, which is where I keep mine. Only the endosperm is being crushed.

If you do get a large amount of husks into your boil kettle then yes you could theoretically get some tannins, but that shouldn't happen unless you've done something wrong with your grain treatment.

The reason your hung bag was stickier than your squeezed bag was that your hung bag had time for wort to evaporate off of it leaving sticky sugar behind, while the squeezed bag was still wet. I bet if you took your squeezed bag and put it in a bucket for 30 minutes it would be just as sticky.
Can I ask why tannins are so bad? Bad flavor?
 

TooDogly

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No offense intended, but There is a lot of misinformation in this post and in this thread in general.

Increased temperature has no effect on lautering efficiency whatsoever. The viscosity of the liquid has zero effect on the amount of sugars extracted. Brukaiser proved this both theoretically and experimentally, and the results are on his website. You can sparge/lauter with room temperature water and be just fine.

As far at the fine crush issue: crushing should not produce small husk particles, unless you are actually grinding your grain to flour. The husks will remain mostly in tact even on a grain mills finest setting, which is where I keep mine. Only the endosperm is being crushed.

If you do get a large amount of husks into your boil kettle then yes you could theoretically get some tannins, but that shouldn't happen unless you've done something wrong with your grain treatment.

The reason your hung bag was stickier than your squeezed bag was that your hung bag had time for wort to evaporate off of it leaving sticky sugar behind, while the squeezed bag was still wet. I bet if you took your squeezed bag and put it in a bucket for 30 minutes it would be just as sticky.
I didn't mean to portray myself as an expert on any of this, far from it, I was only musing based on my own experiences. I do not wish to spread misinformation. However, I was bringing up the viscosity argument because I use the no-sparge method when I BIAB, and I do believe the viscosity has an effect in that case. Do you not agree?
 

TheMadKing

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I didn't mean to portray myself as an expert on any of this, far from it, I was only musing based on my own experiences. I do not wish to spread misinformation. However, I was bringing up the viscosity argument because I use the no-sparge method when I BIAB, and I do believe the viscosity has an effect in that case. Do you not agree?

I'm no expert either, but I argued with one on this very subject once [emoji16].. No I don't agree that viscosity affects lautering in no-sparge. I only say that because I lost this argument once when someone showed me the math. I can't remember the math right now, but basically The difference in liquid viscosity between 70F and 170F of 1.070 gravity wort is almost vzero, so it can't have an effect.

Think of the grain like a sponge full of sugar water. Getting it hot doesn't increase the amount of sugar that comes out because the concentration in the solution stays constent.

A dunk sparge can marginally increase efficiency because that would be like wringing out the sponge, then dunking it in regular water and squeezing again. you are basically displacing the sugar in the sponge with water and then forming a weaker solution.

Now if you start to approach the maximum solubility of sugar in water, the temperature will certainly start making a difference, but no beer wort even approaches that level. So the effect of temperature on lautering is absolutely minimal.

I hope I explained that alright, cheers!
 

TheMadKing

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Oh ok, so the beer would be safe and relatively drinkable? Just kinda bad tasting?

Oh yes, perfectly safe, and drinkable depends on the pallet.. For me, sure I'd probably drink a mildly astringent beer, but some people can't stand it. If it's severe, then no way, I don't enjoy cotton mouth.
 

TooDogly

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I'm no expert either, but I argued with one on this very subject once [emoji16].. No I don't agree that viscosity affects lautering in no-sparge. I only say that because I lost this argument once when someone showed me the math. I can't remember the math right now, but basically The difference in liquid viscosity between 70F and 170F of 1.070 gravity wort is almost vzero, so it can't have an effect.

Think of the grain like a sponge full of sugar water. Getting it hot doesn't increase the amount of sugar that comes out because the concentration in the solution stays constent.

A dunk sparge can marginally increase efficiency because that would be like wringing out the sponge, then dunking it in regular water and squeezing again. you are basically displacing the sugar in the sponge with water and then forming a weaker solution.

Now if you start to approach the maximum solubility of sugar in water, the temperature will certainly start making a difference, but no beer wort even approaches that level. So the effect of temperature on lautering is absolutely minimal.

I hope I explained that alright, cheers!
I had a hard time finding a website that shows the sugar content of wort in relation to the specific gravity, but this one shows some info.
http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm
They say for 1.070SG the sugar would be 25oz per gallon. If you convert that to weight it would be about 18.5% sugar by weight.

This website shows the viscosity of sugar solutions by temperature.
http://www.engineeringtoolbox.com/sugar-solutions-dynamic-viscosity-d_1895.html
According to the table it appears that a 20% sugar (only sucrose, I know, but it's close) solution at 70F would be roughly 2.5 times more viscous than at 170F.

However, this argument about squeezing the bag is fairly moot since, as others have said, you are really not adding that much more liquid (and therefore sugars) to the kettle than has already been dissolved into the five or so gallons of wort. In my experience I've only ever added about a quarter of a gallon more by squeezing or dripping for 30 minutes. If I'm worried about hitting my OG target I'll just add a little more 2-row to the recipe and call it good. ;)
 

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I'd be interested in an experiment to gauge total wort recovered by just letting the bag drain for 30 minutes vs squeezing like a mad man.

I have a hunch there is not much gained if any squeezing vs a patient drain of say 30 minutes.
I haven't done any experiments, but I often leave my bag to drain in a nested-buckets draining setup (no headspace to hang the bag over the kettle on my stove) for half an hour or longer while getting the boil going. After emptying the lower collecting bucket, I squeeze the bag and typically get a liter or two more wort for a typical ~21L batch, though I can't speak to the gravity of that leftover wort. On some brewdays, though, squeezing is a necessity: the oatmeal porter I've got fermenting drained at a rate of about a liter every half hour thanks to the viscous cereal-mashed oats in the mash. Aggressive squeezing was absolutely necessary in that brew - I had 12 liters in the kettle after pulling the bag and needed at least 25 liters for the boil.
 

TexasWine

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According to the table it appears that a 20% sugar (only sucrose, I know, but it's close) solution at 70F would be roughly 2.5 times more viscous than at 170F.
Just to make sure we take this in context, a 2.5 times increase in a small number still results in a small number. For example, if someone asked me to carry a dime in my pocket, I'd say no problem. If I was then asked to carry DOUBLE the weight, and put two dimes in my pocket, I'd still say no problem.

This viscosity issue is the same. Even though viscosity increases with a drop in temp, which is what you should expect, the increase results in a negligible difference to the home brewer when it comes to lautering.

I'll also add that the viscosity of pure water is almost the same as these sucrose mixtures at these temperatures.
 
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