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> Partial (Mini) Mashing, Submitted by Jim Yeager
Jimvy
post Apr 5 2006, 10:06 AM
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Partial (Mini) Mashing
By Jim Yeager


So you’re an extract brewer and you’ve heard the arguments for going all-grain but just can’t convince yourself to do it. Either you don’t have the time or the space or just don’t care to. But, you’d still like to be able to make some of the beers you hear others talk about….that rye pale ale or an oatmeal stout. Any options? You guessed it….partial mash is the answer.

What is partial mashing exactly? Well, quite simply, it’s getting a portion of your wort sugars from mashing and a portion from extract. Generally, all-grainers will tell you, “If you’re going to partial mash, why not mash the whole thing?” But if you have limited space, or are still using your stove, partial mashing is actually a very good option to gain access to some styles not generally available to an extract brewer. Additionally, the use of extract for part of your sugars alleviates some of the concerns over efficiency.

Background

Before we get into the process of the partial mash, a little background information is useful in understanding what mashing does and how it’s different from “steeping” grains. The kilning process does some different things to malt. Grains that are generally used for steeping fall into two categories: crystal malts and roasted malts. Crystal malts are kilned at a high temp while they are still moist. The result is that some starches are converted to sugars and then caramelized. Roasted grains are kilned at an even higher temp which destroys some enzymes. By steeping these grains, you will be able to gain some of the sugars available as well as the roasted characteristics of the darker malts.

Most of your other malts have starches that need to be converted into sugars thru a mashing process. In order to convert, enzymes are required. Base malts already contain these enzymes in differing amounts. If a base malt has a high degree of these enzymes (diastatic power is a measure of strength of starch-reducing enzymes in the malt), it can not only convert it’s own starches to sugars, but it can help convert other grains’ starches, those that may not have enough enzymes to convert themselves.
By contrast, there are grains that are in somewhat in the middle. They don’t really have anything in them already that can be gained from the steeping process, nor do they have enough enzymes to convert their own starches. These are the grains that we’ll focus on for partial mashing, as converting them will help you make some new styles of beer. Examples are flaked oats, flaked barley, flaked corn, and rye.

In deciding which grains to use when partial mashing, we need to consider two things. First, while steeping will work for crystal and roasted grains, we won’t get as much out of them as we would if we mashed. And second, we have to ensure we have enough diastatic power in our grain bill to ensure conversion.

Below is a chart from John Palmer’s How to Brew on malt yields. Pay special attention to the last two columns….this is where we see which malts can be steeped and the extraction difference between steeping and mashing.

Typical Malt Yields in Points/Pound/Gallon


The Process

We’ve got some of the background now, so we’ll get into the process and swing back to recipe design in a bit.

How you go about a partial mash is largely up to you and what equipment you have available. You can use the same equipment as an all-grain brewer or you can scale it back to what you have in your kitchen. I’m going to describe what I view as the simplest approach.

What additional equipment you need:
- a 2nd large pot that is oven safe
- another pot/pan for sparge water
- strainer or colander
- thermometer (if you don’t already have one)

The process of brewing is basically the same as you typically do with extract brewing, except we’re going to add something to the front end—the partial mash. You can use 1 to 1.5 quarts of water per pound of grain, but for our example, let’s take the middle-ground and say 1.25/qt/lb. Put the water in your oven safe pot and bring it up to about 168F. Once there, turn off the heat and stir in your grains. Once they’re stirred in, check your mash temperature. You should hit around 153F…a few degrees one way or the other won’t make a huge difference.

Next, put the kettle of grains in the oven set on about 160-165F and let them sit for 45-60 minutes (if your oven doesn’t go that low, one alternative is to set it at 200F and then turn it off during the mash). While you’re waiting, heat up the sparge water to 170F…figure 1.5 quarts per pound of grain used in the mash.

(IMG:http://webpages.charter.net/jim.yeager/Shared%20Beer%20Photos/partialmashoven.jpg)

When the mash is complete and the sparge water is ready, set the colander inside your other brewpot and gently pour the mash thru it. Put the grain back in the original pot and then fill it with your sparge water (effectively creating another mash). Let this sit about 10 mins and then poor thru the colander again. Discard the mashed grain.

Congrats! You’re done with your mini-mash!! At this point, top up with water to get to what you typically boil and add your extract/hops as you normally do.

Recipe Considerations

As I mentioned above, there are two major things to consider when coming up with your partial mash recipe. First is the “efficiency” of steeping versus mashing and second is the amount of diastatic power in the mash. For the first, you can use the table above to help choose but I view this as a secondary choice, as we’d probably mash all the specialties if we didn’t have the limiting factor of diastatic power. As for how much diastatic power our mash has, unfortunately, there isn’t a quick and easy rule. Personally, I would suggest trying to keep your grains requiring conversion to no more than 30-40% of your total mash. I’ve heard of some folks going as high as 60%, but they also changed their base to 6-row for the additional diastatic power it has over 2-row.


Mash Tun Alternative

If you would rather not use the oven, another alternative is to use a small cooler. You can take just about any cooler and with a few adjustments, set it up for mashing. What you need is:

- a #5 stopper (in place of the drain)
- a short 3/8s piece of copper tube (connected to the braid)
- braided hose for the inside of the tun
- a nylon valve to control the out flow while sparging

If you don’t want to build it yourself, you can find pre-made coolers for mashing like this one for a reasonable amount:

(IMG:http://www.heartshomebrew.com/html/images/mash.jpg)

Partial Mash Cooler


Advanced Topics

Even when doing a partial mash, the things all-grainers worry about become important, though to a lesser degree. I would view the following topics as “optional” for most folks, but for some, it may have a larger impact on efficiency. My advice is to jump right in and start partial mashing. Get some experience under your belt first and then, if you want to fine-tune your brewing a bit, dig in to these topics.

pH in the Mash – For mashing, you want your pH of the mash to be about 5.0 to 5.5 so that the enzymes converting starch to sugar are able to do their job. To start, you can get a water report from your water supplier and it should give you a range of the pH. If it’s in the 6-7 range, chances are you don’t need any adjustments. The reason why is that the grain you use in your mash usually brings down the pH. Darker grains are more acidic than lighter grains, so use of roasted and crystal malts will bring down the pH more than base malts. If your pH is much higher than this, I suggest using a product by Five Star Chemicals called 5.2 pH Stabilizer. It’s designed to adjust your pH to 5.2 regardless whether your water is higher or lower than that. It takes the guess work out of it.


pH of the Sparge – You really only worry about your sparge pH in how it relates to your mash. You don’t want your mash pH to climb to over 6.0 during the sparging process, as this will lead to tannin extraction. What we want to do is ensure our sparge water isn’t over 6.0 pH so that the mash pH doesn’t climb faster than it has to. The best way to do this is to use an acid, such as lactic. For batch sparges though, you could use the pH Stabalizer for both if you desire. Lactic is cheaper, but in the small amounts you’ll be working with, it may not be a major factor.

Minerals—I’m not going to spend a lot of time going thru all the minerals and their impact, but there are a couple of minerals you really need to have in your water in order for your mash to be successful. First off calcium is the most important, as it enables a lot of enzyme and protein reactions. The appropriate brewing range = 50-150 ppm. Magnesium is also very important, though to a lesser degree. It acts as a yeast nutrient in small amounts. The appropriate brewing range is 10-30ppm.
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