I'd like to try a mini-mash in my next batch of beer. How do I do that, and what equipment do I need? Is a mini mash different from a partial mash?

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If you're an extract brewer who steeps some specialty grains with your batch, you're pretty much there. Almost all extract recipes use some specialty grains anyway, so the switch should be easy to do. Going with a mini-mash is an easy way to add some gravity points to your extract recipe. It also allows you to work with some grain types that don't steep well.

Partial mashes come in different varieties, depending on the amount of grain you're set-up can handle. Once you get comfortable with a small-size mini-mash, you can step up to a larger partial mash. For competition purposes, the AHA defines an extract batch as one that gets up to half of the fermentables from grain. Hence, you can see that a partial mash can get pretty big. Ultimately, you'll find that it isn't much work to make the jump to all-grain brewing.

Let's start first with the smallest mini-mash. Suppose for a 5-gallon batch of beer, you have a half-pound of crystal malt, which you plan to steep. When you get your ingredients, buy a half-pound of pale malt along with the malt extract and hops. Pretty much all you have to do is throw the pale malt in with the crystal when you steep it. The only difference is that for best results, you want to try to keep the temperature and water volumes under tighter control. The reason for this is that the enzymes in the pale malt, which are needed to convert starch into sugar, work in a narrow range. In the example above (½ pound crystal and ½ pound pale malt) measure out 1½ quarts of water. Heat it in a 3 quart sauce pan up to about 160°F. Shut off the heat, and dump in the grain. Then check the temperature again. You want it to be between 150°F and 155°F. If it is a bit too cold, turn the heat on to low, and stir until it gets within range. Don't overheat it, or else the enzymes will decompose. Cover the pot and let it sit for at least half and hour, and preferably a full hour. As the final time approaches, heat up another 2 quarts of water to 170°F.

Then it is time to sparge the grains. Pour the mash through a kitchen strainer so that the steeped liquid collects in your brew pot. Then carefully pour the hot water over the grains and collect that in your brew pot too. What, you've been doing that anyway? Hey, I told you it was easy. At this point, the mini-mash is done, and you proceed like a regular extract brew session. One further thing you should do, though: At the end of the brew session, see if the starting gravity of your batch is higher than you would get from just the extract alone. If it is, you know the enzymes did their job. Each pound of grain should raise the gravity by about 5 points in a 5-gallon batch. If you gravity isn't any higher, it probably means you missed the temperature target.

Note that there is more than one way to do this. Some people prefer to use a grain bag. In this case, use the same volumes as described above. But rather than putting the grains in the pot, you out them in the bag, and the bag into the pot. When it comes time to sparge, simply pull out the bag, let it drain a moment, and then put it into the second pot of water. Let it soak a minute or two and then pull it out again.
If you want to scale the process up, you might want to invest in a mini-mash-tun. I made my first one by drilling holes in the bottom of a coffee can. You can make a much more elegant one by buying an E-Z masher screen from the shop and put it into a 2 gallon beverage dispenser. That would let you work with up to 5 pounds of grain. When you make this step, you need to make sure the tun is insulated, since you can't put the plastic container on the stove. You'll have to be a bit more careful with the initial water temperature, which you'll find is good practice for all-grain brewing.