Squeezing the Bag

[TheMadKing]

Can I ask why tannins are so bad? Bad flavor?

They produce an astringent mouth feel, like sucking on tea bags

 

[TooDogly]

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?

 

[Crohnnie]

They produce an astringent mouth feel, like sucking on tea bags

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

 

[TheMadKing]

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]

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]

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.

 

[FatDragon]

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]

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.

 

[goforevercrazywithit]

Can I ask why tannins are so bad? Bad flavor?

They add astringency to the taste