Advice on cold steeping dark grains

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Monkhouse

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I want to do this Gordon Strong impy stout recipe but haven’t got the mash tun capacity to do add the dark grains at vorlauf so wanted to cold steep them separately for 24hrs, after which I would be adding this cold steeped wort to the boil at about 10 min left before flameout. The light grains and base malt will be an overnight mash. My worry is though that if I’m cold steeping the dark grains then I won’t get any fermentable sugars from these and so won’t be able to hit my OG target.
Any suggestions? I know Foxy is well clued up on cold steeping so hoping he will come along and comment but if anyone else knows about this please comment!
Cheers
Dave
 

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You don't get fermentable sugars from the dark grains. These days I do hot seeping for brews with significant quantities of dark grains simultaneously with the mash. Works well but you do have to be careful with your volumes.
 
You don't get fermentable sugars from the dark grains. These days I do hot seeping for brews with significant quantities of dark grains simultaneously with the mash. Works well but you do have to be careful with your volumes.
Yeah but you must get some sugars from some of the grains added at vorlauf in that recipe, otherwise it’s just 8.6kg of light grains to produce 25litres of 9.9%abv beer and that just wouldn’t happen especially with an fg of 1.025. You wouldn’t get an OG of 1.098 with 8.6kg of basemalts. This is what’s confusing me
 
Yeah but you must get some sugars from some of the grains added at vorlauf in that recipe,

You're absolutely correct, you do get sugars from dark malts. There was an argument about it recently.

https://www.thehomebrewforum.co.uk/...st-malts-outside-the-mash.104895/post-1275699

There is also some experimentation done on the sugars you extract from middle and dark roasted malts showing that they are (contrary to strong opinions online) indeed fermentable - about 50% or so from memory, but here is the thread.

https://www.homebrewtalk.com/threads/testing-fermentability-of-crystal-malt.208361/

I think the above thread also did an experiment showing that if you add the dark grains to the mash, it will increase the fermentability of the sugars in crystal malts etc (which makes sense because the beta amylase don't just magically ignore dextrins because they came from pre-roasted grains)
 
With low temperature and pH it shouldn't. I'm pretty sure others have overnight mashed stouts and porters without issue.

If the concern is about converting or reducing sugars you've extracted from the cold steep, then the steeped liquor needs to see enzymes in the mash.

If the recipe calls for grains at vorlauf, another option is to add the steeped liqour then. If capacity is an issue, you could draw of some first runnings to make space.
 
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With low temperature and pH it shouldn't. I'm pretty sure others have overnight mashed stouts and porters without issue.

If the concern is about converting or reducing sugars you've extracted from the cold steep, then the steeped liquor needs to see enzymes in the mash.

If the recipe calls for grains at vorlauf, another option is to add the steeped liqour then. If capacity is an issue, you could draw of some first runnings to make space.
So adding the cold steeped liquor to the main mash as strike water at 65c would have the same impact in terms of getting the fermentable sugars as adding the dark grains straight to the mash but without the astringency?
 
No, it'd be the same mashing normally with dark grains, but without the extra volume of the grain.

Part of (or perhaps the main) reason Gordon Strong adds at vorlauf is for simplicity of pH management. It's debatable that whether mashing dark grains separately actually extracts less astringency, or just extracts less of everything, ie has the same effect as using less grain in the mash. His observation of less astringency is the outcome of his mash regime, rather than the reason for it.
 
So adding the cold steeped liquor to the main mash as strike water at 65c would have the same impact in terms of getting the fermentable sugars as adding the dark grains straight to the mash but without the astringency?
Yes…probably…

Astringency comes from the husks of the grain which you will already have removed if you’re only adding the steeped liquor.

If what you’re trying to eliminate is bitterness from roasting you may see less improvement than you would like because your steeped liquor will go through a full boil. I probably likened this previously to coffee stewed on a hot plate. I get this might be subjective but stewed coffee always tastes harsh and bitter to me.

An interesting refinement might be to take some wort from the mash (with its enzymes so before mash-out) and add it to the steeped liquor. Hold it at mash temps while you’re doing other stuff and add it toward the end of the boil. This could see you getting maximum fermentability from the dark grains and avoiding roast bitterness.

Do bear in mind you can use debittered grain (has had it’s husk removed) such as Carafa Special III to avoid astringency.
 
Astringency comes from the husks of the grain which you will already have removed if you’re only adding the steeped liquor.
A fair point.

Although, temperature tends to speed up extraction, I kind of expect a 24hr cold steep would extract tannins too, much in the same way as tannin extraction from tea doesn't stop when a brew goes cold. I feel it's all tied together, less tannin extraction also returns less sugar, colour and flavour extraction. Given those husks are on the outside of the part of the grain.
 
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A fair point.

Although, temperature tends to speed up extraction, I kind of expect a 24hr cold steep would extract tannins too, much in the same way as tannin extraction from tea doesn't stop when a brew goes cold.
Maybe so, I’ve never seen or looked for any references to inform that debate I’m afraid. For me at least, any extraction that might occur through cold-steeping is below my taste threshold - though to be honest I don’t remember picking up any astringency even when doing a full mash with dark grain 🤷‍♂️

I mostly cold-steep to avoid excessive roast bitterness.
 

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