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Author Topic: Gray film developed in kettle while brewing  (Read 1683 times)

Offline akaRedbeard

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Gray film developed in kettle while brewing
« on: July 19, 2020, 10:41:04 am »
I was making a pale ale with 2row, white wheat and vienna. Mash went really well, but halfway through the boil I noticed a lot of white particles were floating around. I thought it was probably just grain debris although I did have a clear run-off. Then I got this stringy gray slime that seemed quite odd. Has anyone else experienced this? Is it possibly protein from the wheat? It may be normal but I have not encountered this before. Note- there were no hops in the boil. Thanks for any help!

Offline narcout

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Re: Gray film developed in kettle while brewing
« Reply #1 on: July 19, 2020, 10:58:14 am »
That just sounds like hot break to me.  Sometimes it will coagulate into little, flat pieces that look like egg drop soup.  Sometimes it looks more like short pieces of string.  You may also get a layer of tan or grayish foam in varying thicknesses.

Depending on your mashing technique and equipment, you can leave more or less of those proteins and polyphenols behind in the mash tun. 

If you haven't yet added hops, you can skim that slime/foam off the surface of the boil and discard it if you want.
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Offline akaRedbeard

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Re: Gray film developed in kettle while brewing
« Reply #2 on: July 19, 2020, 11:05:19 am »
Ok cool. I was hoping thats what it was but wanted to be sure. Thanks

Offline Andy Farke

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Re: Gray film developed in kettle while brewing
« Reply #3 on: July 19, 2020, 05:14:07 pm »
I've gotten compact gray debris (slime-like) in my mash tun before too...I figure it's just insoluble proteins from the grains.
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Offline BrewBama

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Gray film developed in kettle while brewing
« Reply #4 on: July 19, 2020, 06:38:04 pm »
To the OP:  FWIW: I like to skim the ‘stuff’ from the BK. Not sure it matters. Some say it doesn’t. ...but I like my results so I continue to do it. (I skim soups and stews also.)

I've gotten compact gray debris (slime-like) in my mash tun before too...I figure it's just insoluble proteins from the grains.

Possibly what you’re seeing is teig (which is an indicator of HSA according to the MBAA).

Bamforth states,"oxygen reacts with gel proteins to cross-link them and that causes this sticky gel formation called the 'teig'".

Teig can cause lauter problems because it forms an impenetrable layer so the wort flows around the grain bed if at all (stuck lauter).  You can cut the layer with a knife to help the liquid flow thru the grain vs around it.

The thought is reduce oxygen in the mash to reduce teig. I believe proper pH helps as well but I can’t find a reference so that’s just me saying that.

One way that I found helps is to underlet the mash with brewing liquor. I started underletting to reduce the hazard of lifting 5.5 gal of ~160*F strike liquor to pour it into a mash tun. I add the grain to the mash tun and pump the water thru the drain valve. It’s a lot safer to pump than lift.

A welcome byproduct of underletting is a lack of dough balls I’d get when I added grain to water.

Another nice side effect is no more teig. I understand that pumping water from below the grain bed helps reduce O2 in the mash.

Also to limit O2 pick up 1) I do not open the MLT during the mash. I tried a mash cap but it was a PITA and my MLT is nearly full anyway so I figure the MLT lid is the mash cap. 2) I recirculate during the entire mash and ensure the recirculation return is below the liquid level so I don’t pick up O2 that could be caused by splashing.

I nearly always had a teig layer but using these techniques has eliminated it altogether.

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« Last Edit: July 19, 2020, 08:07:15 pm by BrewBama »

Offline Bilsch

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Re: Gray film developed in kettle while brewing
« Reply #5 on: July 19, 2020, 07:20:04 pm »
Good thing is that while you cant remove the proteins from the mash, you can remove the oxygen. And with that, goes the teig. Cool huh?

Offline Andy Farke

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Re: Gray film developed in kettle while brewing
« Reply #6 on: July 19, 2020, 08:41:50 pm »
I've gotten compact gray debris (slime-like) in my mash tun before too...I figure it's just insoluble proteins from the grains.

Possibly what you’re seeing is teig (which is an indicator of HSA according to the MBAA).


Of *course* there has to be a German word for that stuff! :D Based on the descriptions, I suspect teig might be exactly what I'm seeing. It certainly gets compact. I only see the stuff every so often (every 10 brews?), so should probably take notes on the conditions/grain bill that are associated with it. I do a "faux underletting", in which I fill my mash tun with water, let it settle down to the target temperature, and then gently add the grains. I'm sure there is likely more aeration than simple underletting, but in terms of anecdata my technique certainly appears to have less agitation than when I add water to grains in the tun. If I ever get a pump for my brewhouse, I'll probably play more with underletting...
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Offline ynotbrusum

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Re: Gray film developed in kettle while brewing
« Reply #7 on: July 20, 2020, 05:47:59 am »
Teig can be on the bottom of a mash tun, also.
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Offline BrewBama

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Gray film developed in kettle while brewing
« Reply #8 on: July 20, 2020, 05:57:43 am »
You can only do what you can do. Sounds like you have a 10% ‘problem’ and I’m applying a 300% solution.

One way I have seen others underlet without a pump is to gravity feed brewing liquor under the grain bed via a hose from the drain valve of the hot liquor tank. That’s actually how I batch sparge.

Once I drain the MLT of the 1st runnings, I attach my hot liquor tank (a water cooler) to the return side of the recirculation circuit. It gravity feeds under the grain to fill the MLT. Then I recirculate normally and drain the MLT thru the pump to  complete the boil volume in the BK.


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« Last Edit: July 20, 2020, 06:00:56 am by BrewBama »

Fire Rooster

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Re: Gray film developed in kettle while brewing
« Reply #9 on: July 20, 2020, 06:28:43 am »
I use a 16 QT SS pot to mash/boil wort, use white wheat most times.
A very slow mild boil is used, the film on top is skimmed off with a small spoon.

"Many years ago" during the summer I would visit
my grandmother for a week.  Wheatena was usually
made for breakfast.  She said wheatena never
use to have a film on top when made years prior.
She said something changed, chemical, additive
,preservative, process, who knows.  She use to skim off
the film with a small spoon.
« Last Edit: July 20, 2020, 06:52:03 am by Fire Rooster »