Filtering boil through grain bed from mash?

Has anyone ever filtered post boil through the grain bed? I consistent struggle with clarity even using a paint strainer as I pour into my primary and cold crashing (to the best of my abilities (45-50f). I imagine if I were to do this, say after I get my wort down to ~120 I could (a) get the hops and other proteins filtered out pretty nicely and (b) probably cool a few degrees as the room temp grain bed absorbs some of the heat.

Is there a pretty simple reason I'm missing why I've never heard of this?

Yes there is. Sanitation. Things are growing in that grainbed while you boil and cool. This is where the idea "sour mash" came from. It's a breeding ground for wild yeasts/bacteria.

In the spirit of adventure, I suppose you could try to keep the mash tun (if direct fired) at or above 150-160 during the whole boil to pasteurize it, but you'll never keep it all at that temp so you'd have to aim for more like 170F IMHO...and ideally you'd recirc your boiling wort through it for the last 5-10 minutes of the boil, but then there are people who will tell you to look out for tannins...and you're still not as safe as you could be from a sanitation standpoint.

I'm not certain, as I'm very new. However, I'd be worried that, having just boiled the wort and killed any foreign bacteria, by straining it through the spent grains, you'd pick up a whole world of new strains (pun intended).

Plus, I've read on other threads that the grains can "sour" pretty quickly if left out to "room temperature."

Ever smell spent grain that has been left out overnight? The mash isn't boiled. You will be "filtering" nice clean wort through a dirty, infected grain bed. At 120 you would also be pulling tannins out of the husks.

You would end up with a nasty astringent mess of a beer.

My 2 cents anyway.

The biggest concern I would have would be contamination. That bucket of grains has been sitting four an hour around 160-170deg a lot of things can start to grow at that temp. Also tannin extraction could become a problem.

After cold crashing, take everything out of the wort (Immersion Chiller, Hop bag if used, etc), then use a sanitized spoon to stir the wort up into a whirlpool, and let it sit for another 30-40 mins. Then rack from the edge. You should get a trub cone in the center if you do it right....

Keep your wort protected from air at all times after you stop the boil too. I use sanitized foil to cover any gaps that my lid doesn't cover around the immersion chiller. Recover the wort after you stir it too.

Oh and trub in your fermenter isn't such a big deal either. It should all settle out by the end of your ferment anyway.

I also rack from my brew kettle to the fermenting bucket in an effort to keep trub & hop pellets from transferring.

Nylon paint strainer bag around your racking cane out of primary....or just gently lower the racking cane through the clear fermented beer as it drains into keg/bottling bucket.

stblindtiger said:

Nylon paint strainer bag around your racking cane out of primary....or just gently lower the racking cane through the clear fermented beer as it drains into keg/bottling bucket.

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lol...

But handy advice nonetheless

stblindtiger said:

Ever smell spent grain that has been left out overnight? The mash isn't boiled. You will be "filtering" nice clean wort through a dirty, infected grain bed. At 120 you would also be pulling tannins out of the husks.

You would end up with a nasty astringent mess of a beer.

My 2 cents anyway.

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Heat doesn't really pull tannins out of grain husks, and 120F is very low heat anyway. Mashing is around 150F and I usually sparge with ~190F water.

vbwolpert said:

The biggest concern I would have would be contamination. That bucket of grains has been sitting four an hour around 160-170deg a lot of things can start to grow at that temp. Also tannin extraction could become a problem.

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Pasteurization occurs at temperatures above 140. Not much of anything can grow or live at 160-170F except maybe some archaebacteria that live by volcanic vents on the ocean floor.

I_Brew_Drunk said:

Has anyone ever filtered post boil through the grain bed? I consistent struggle with clarity even using a paint strainer as I pour into my primary and cold crashing (to the best of my abilities (45-50f). I imagine if I were to do this, say after I get my wort down to ~120 I could (a) get the hops and other proteins filtered out pretty nicely and (b) probably cool a few degrees as the room temp grain bed absorbs some of the heat.

Is there a pretty simple reason I'm missing why I've never heard of this?

Click to expand...

My grainbed is definitely not at room temp after the boil. Have you ever taken the temperature? Mine is usually still above 150 when I'm trying to clean it out, so you probably won't get any cooling from that. It should be pretty sanitary, but I still wouldn't run my wort through it. You'll probably end up rinsing a bunch of starches out that won't have a chance to be boiled and precipitate out (hot break). So you would end up with a cloudier beer then if you didn't do it. Plus I wouldn't trust it to be completely sanitary.