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Water-to-grist ratio and grain absorption

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frankvw

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Because many home brewers in this area (including yours truly) brew with borehole water from a dolomite layer which is so hard it can be described as liquid pebbles and has a high pH as well, I have tried to observe the recommendation of not using more than 2 quarts of water (2L) per pound of grain (450 gr.) when steeping malts. I've tasted extracted tannins more times than I care to remember.

But after doing a small scale test with Crystal 60 (Caramunich III) I have my doubts. Due to grain absorption (which for Caramunich III may be higher than average, I don't know) this leaves me with very little wort. Of course I could sparge, but then I'd risk tanning extraction again. Which I could avoid by acidifying my sparge water, but then why not do that with the strike water and simply use more water.

So. What is your preferred water-to-grist ratio when steeping grains, and why?
 
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frankvw

frankvw

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Steeping at 65C. But I would like to avoid sparging and keep things as simple as possible. I'm actually trying to make partial mash beer kits for novice brewers, and simplicity is key there. :)
 

IslandLizard

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If you're steeping with 1.5 to 2 quarts (liters) per pound of grist, you do need to sparge, or you'd lose a lot of the "good stuff" trapped in the wet grist, easily as much as 25-35%.

Acidification of your hard steeping water, and perhaps the wort before the boil, is the answer.
Do you have a way to measure pH quite accurately?

For partial mash, using base grain with diastatic power to convert grain starches to sugars, pH is even more important. As is a sparge.
 
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frankvw

frankvw

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Obviously the water to grist ratio is going to be a tradeoff between extraction efficiency and tannin extraction. Less water = less efficiency = less tannins. So yeah, sparging does seem to be the best bet.
 

IslandLizard

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As long as you keep the grist pH during steeping (or sparging) under 6.0 (5.8 is advised) tannin extraction is minimal, pretty much regardless of temp. For example, decoctions are boiled for 10-20 minutes, sometimes longer or multiple times, but due to the pH being below 5.8 (usually mash pH is kept between 5.2 and 5.4), there's no risk of tannin extraction.

http://beersmith.com/blog/2017/02/28/extract-beer-brewing-tip-dont-steep-grains-with-too-much-water/

Grain, especially crystal and roasted malts will acidify the water they're in, but if there's a lot of buffering due to high mineral content and/or alkalinity in the water, it won't drop it low enough. That's where using a small amount of acid can help, even when your alkalinity is high. You still need to deal with the high mineral load, which can be beneficial for some beer styles (most darker beers, Stouts), not so for others (most lighter beers, Pilsners). An RO filter can help remove much of those minerals, or perhaps you can buy RO or distilled water at a decent price. Here in the US we can get RO water for $0.39-0.60 a gallon. RO filtering systems can be had for as low as $100-150. I understand YMMV where you are.

Take a look at the stickies in the Brew Science forum and learn about controlling your brewing water.
 
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frankvw

frankvw

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Thank you, @IslandLizard, that does help. Now if only everyone could agree on safe limits: one reference claims that 4L/kg is the maximum ratio you should use, another puts it at 8L/kg.

I suppose I'll have to experiment and see how far I can take it.

Tnx!
 

IslandLizard

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Thank you, @IslandLizard, that does help. Now if only everyone could agree on safe limits: one reference claims that 4L/kg is the maximum ratio you should use, another puts it at 8L/kg.

I suppose I'll have to experiment and see how far I can take it.

Tnx!
Do those references hand us any clues as to why they set those ratio maxima?

Mash ratios of 1.5 (1.5 qts of water per pound of grist) are very common. BIAB brewers who do not sparge are closer to 3.0. Now their mash is lot thinner than twice that of a 1.5 ratio. This is due to grain absorption, which is a constant, around 0.13 gallon per pound of grist. IOW, it takes a pint (half a quart) to merely wet (saturate) each pound of grain to the consistency of a very thick porridge. After that, any extra water makes the grist looser, thinner, more stirrable, which helps with extraction and conversion, up to a certain point, where it gets too diluted and enzyme activity isn't as efficient.

In that light, a ratio of 4 l/kg is around 2 quarts/pound. 8 l/kg pushes that to 4 qts/lb, quite a bit thinner than many full volume BIAB mashes. It may be OK for steeping, perhaps a bit thin for some mashes.

When steeping malts, the amount of grist used is much lower than in a mash, there's no base malt present. As long as the pH remains under 5.8, not sure if there are any detriments from steeping in much larger volumes of water. One will get better extraction in a roomy water volume without having to resort to sparging, there are diminishing returns.

Many homebrew books and recipes tell us to steep the (steeping) grains in 2-4 gallons of water for 20-30 minutes, not in 6 or more gallons. Aside from it may have something to do with partial boils, it surely helps keeping pH lower without having to delve into water chemistry, pH testing, and mineral corrections.
 
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