Using a boiler to step mash

[Dr Jacoby]

I had an idea over the weekend and wanted to run it by people here to see if it makes sense.

I was conducting a simple two step mash (I doughed in at 55C for a protein rest and added water to raise the temp to 64C for the main mash rest - I was looking for a highly fermentable wort). But as I was draining the first runnings I thought, why not raise the temp in the boiler to 70C and hold for 20 minutes to allow some dextrins to be formed for a bit of body.

Ok, let me anticipate some objections.

First, won't the enzymes necessary for conversion be left behind in the grains? How will conversion take place without them? Most enzymes are active in the liquid portion of the mash, so there should be no shortage in the first runnings to allow extra conversion to take place. Think of a decoction mash where the advice is always to remove the thickest part of the mash so that you don't denature the enzymes in the liquid portion. Most of the enzymes in the mash end up in the liquid, not stuck in the grain. 

Second, there will be no conversion of the sugar left behind in the grain once the first runnings are drained. True, but so what? Most of the sugar will drain out with the first runnings and as I just mentioned above, there should be more than enough enzymes in this liquid to allow for further conversion at the higher temp. This is sure to have a big effect.

Third, if you drain the first runnings without first mashing out at a higher temp, won't you get poor efficiency? Yes, there will be relatively poor efficiency on the first runnings but you can compensate for this by using a higher temp infusion for the sparge. Overall the efficiency shouldn't suffer all that much.

Maybe there are other more serious objections but I can't think of any. So I was thinking I might try the following procedure:

1. Dough in as normal to hit the first desired temp (say 55C).
2. Raise the temp for main mash rest (as say 63C).
3. When rest is complete (say after 40 minutes), drain first runnings and raise the temp to 70C in the boiler and hold for 20 minutes for an alpha amylase rest (dextrin rest).
4. In the meantime, heat up sparge water, add to grain and allow to sit until dextrin rest is complete.
5. Drain second runnings and get the boil underway.

And there you have it. A three step mash with no special equipment. Can anyone see a problem with this?

[DEMPSEY]

As I understand mash science the little amy boys with their choppers can only chop what the big amy boys chop first. So if it is not hot enough then the big amy boys will work slowly and only chop a few big chunks of dextrins. These big dextrins will quickly be chopped up by the little amy boys into maltose'ses zz iss . This will leave behind alot of giant starch trees still waiting for conversion.

[UpsidedownA (Andrew)]

I can't see any problems with it. Basically you're solving the mash tun capacity problem by using the boiler. As long as you do rest it at 70 you shouldn't have a problem with unconverted starch.

[Dr Jacoby]

Basically you're solving the mash tun capacity problem by using the boiler.

Mash tun capacity is not really the problem though. I could easily accomodate a second infusion of water to raise the temp to 70C, but this would thin the mash to such an extent that the enzymes would not work efficiently.

The real problem is the fact that I cannot heat the mash liquor in my cooler box. The boiler offers a solution of sorts to this problem. It's not ideal but I think it does give me more flexibility.

[mr hoppy]

I did a step mash in a gas boiler for a wit recently. I put the grains in a muslin bag and once I'd finished mashing I removed the bag from the pot leaving the first runnings behind, like a BIAB. I then put the bag of grain in the picnic box tun and sparged from here back into the boiler, basically using it as a lauter tun. Probably not the route for a huge grain bill but for the wit it worked quite well.

[Hop Bomb]

Is your boiler gas or electric? I was thinking of upgrading my cooler mash tun to a keggle mash tun with false bottom before the end of the year to allow for step mashes. My only concern is using flame to heat the mash. Would the mash closer to the bottom be hotter than the top? Or does it heat evenly with convection?

[Dr Jacoby]

My boiler is electric. I definitely wouldn't use it to heat grain directly. If you were to install a false bottom and situate the element below this, I suppose you could heat the mash that way. I'd be worried that the liquor below the false bottom would be heated too aggresively. You'd have to stir the mash quite a lot to help even out the temperature.

The other option is to heat the vessel with gas. This would probably be a safer way to do it in the sense that it would be les likely to scorch the liquor but again you'd need to stir it a lot.

It's for these reasons that people build HERMS and RIMS systems to help regulate the temperature without the risk of scorching.

[DEMPSEY]

I have done 1 brew with my new HERMS system and the HERMS work perfectly. Because I am pumping the wort liquid around through a pipe which is in a bath of temp controlled water,you can easily control the mash temp.

[UpsidedownA (Andrew)]

Basically you're solving the mash tun capacity problem by using the boiler.

Mash tun capacity is not really the problem though. I could easily accomodate a second infusion of water to raise the temp to 70C, but this would thin the mash to such an extent that the enzymes would not work efficiently.

The real problem is the fact that I cannot heat the mash liquor in my cooler box. The boiler offers a solution of sorts to this problem. It's not ideal but I think it does give me more flexibility.

Sorry, why is a thin mash a problem? You haven't changed the number of enzymes and you haven't changed how much starch they have to convert. So why should thickness have an impact (assuming the mash is at the right temperature - I think I've heard a thicker mash to some extent protects enzymes from hotter temperatures). I suppose a thinner mash might have a different pH other things being equal.

Is that the problem? A thinner mash takes the mash pH out of the optimum range? You could counter that by adding more calcium.

[mr hoppy]

Forgot to mention my brew pot / mash tun is aluminum - with a SS pot you'd probably want a heat diffuser.