The why you shouldn’t bother part is easy so let’s start there.
Save yourself a bunch of time and hassle – just buy the pre-gelatinized “flaked” grains at the homebrew shop. Run them through your mill with the rest of your grain and be done with it. Yes, they cost more, but this isn’t Anheiuser-Busch-In-Bev-Whatever-Company-They-Buy-Next, Inc. You’re using a few pounds, not a few tons.
But maybe you’re working with some crazy ingredient that isn’t available at the home brew store and you want to be sure you’ll get all of those gravity points. Or you’re like me and just want to experience it – and decide for yourself whether its worth the trouble or not. If that’s you – here’s the how to do it part.
So what the heck is a Cereal Mash anyway? Basically, a Cereal Mash is used to break down the starches in un-malted grains (or other adjuncts) to make them more easily accessible to the enzymes in the main mash. Typically you would use it for grain bills that include a large amount of corn or rice – but it could be done with any un malted grain or other starch source.
One more note before we get started. You still need the enzymes in the main mash to do the actual conversion of the starches to sugars – this process only “unlocks” them. Since the cereal grains are un-malted they can’t convert themselves – and we’re going to kill any enzymes with heat anyway – so this won’t work for an extract+steeping grains recipe.
There’s a pretty good description of the process in John Palmer’s How to Brew (p. 173) but the first time I tried it a few things weren’t completely obvious – so here’s my version.
The only extra equipment you might need is a pot large enough to hold your adjunct and the mash water – about 3 quarts per pound of grain. Once the cereal mash is complete you can just add it directly to your main mash and continue your brew session as you would normally. This means you’re probably going to be juggling 2 mashes at once – although you could do them serially (hah! get it?). Either way you will need to account for the temperature of the cereal mash when you add it into the main mash.
That out of the way – on with the show.
- Crush your adjunct. It makes things go a little faster. Rice or corn you can mill down to the size of grits or polenta. Other grains just run through your grain mill.
- Mill about .5 lb (~.25kg) of malted barley and add to your ground adjunct. The enzymes will help to break down the starches more effectively. This part isn’t strictly required – you could just go straight to step 4. Give it a try both ways and see what works best for you.
- Infuse your crushed cereal (adjunct+grain) with about 3 quarts of water per pound of cereal. Since we’re “direct firing” the pot the mash can scorch easily. The extra liquid helps with that. From this point on you need to stir almost constantly -also to prevent scorching. The temperatures are kind of up to you. If you like step mashing – feel free do it here as well – start at 105ºF-122ºF-145ºF-158ºF (or a standard 40-50-60-70 if working in ºC). Otherwise just mash in at 155ºF for non rice or corn grains and 165ºF if your adjunct is rice or corn. Rest about 15 minutes at each step.
- After your temperature rests are done slowly raise the mash to a boil. Don’t forget to stir – lots! If you made the enzymes help along the way the mash should start to break down after about 15-20 minutes. It will change from looking like a bunch of grain in water to a more uniform goo that will coat the back of a spoon. If you had lazy (or no) enzymes or didn’t crush your adjunct very fine then it could take longer – just keep boiling you’ll get there.
Those starches won’t stand a chance now! Add the cereal mash to your main mash tun and aim for the first rest as specified in your recipe. If you reach the prescribed pre-boil gravity then you did a good job and have extracted the sugars you needed from your adjunct.
If you’re looking for a recipe to test your new cereal destruction skills on – try this American Lager.
Photo courtesy of lalala_.