| The Double Luck Brewing Process: |
| Mashing |
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Mashing |
The mashing process is used to convert the starch remaining in the malt into sugar. The organic chemistry involved in this process is far beyond the scope of this material. We will simply state that under properly controlled conditions of temperature and acidity (pH), the natural enzymes still present within the malt will convert the starch into sugar. While the following is vastly over simplified, it can be stated that two types of sugar are produced - simple sugars and complex sugars. Simple sugars are molecules with short chains of organic structure. Simple sugars are excellent as food for most living organisms, such as yeast, because the are easily digested. Simple sugars are fermentable, and so will be converted into alcohol during the fermentation process. On the other hand, complex sugars are molecules having long chains of organic structure, and are not easily digested. These sugars are not fermentable, and will remain in the beer after fermentation is complete. These non-fermentable sugars will provide flavor, sweetness, and mouth feel to the finished beer.
Striking the right balance in the relative amounts of simple and complex sugars is an important factor in the final outcome of the beer. We can exercise a certain amount of control over the types of sugar that are produced during the mash. While lower temperatures promote the production of simple sugars, higher temperatures will favor the production of complex ones. The amount of water used is also a factor, because thicker mashes promote the production of complex sugars. Other factors effecting this balance are the acidity of the mash, and the length of time that the enzymes are active.
There are essentially two techniques that can be used for the mashing process. The simplest, called infusion mashing is one in which the temperature is raised by the addition (infusion) of hot water. A simplified form of this technique, in which the temperature is raised only once, is called a single infusion mash. This is the most common mashing technique used by homebrewers, and will be described in this material. Another mashing technique, called decoction mashing is one in which the temperature is raised by removing some grain from the mash, heating it directly, and remixing it with the original mash.
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We start the process by preparing the water to be used. It may need to be treated with brewing salts, such as gypsum, so that the appropriate amount of water "hardness" is achieved. Different styles of beer have slightly different requirements; ales are best brewed with harder water, while lagers and stouts are better when softer water is used. We prepare the mash tun by adding approximately one quart of hot brewing water (at approximately 180°F) for each pound of grain to be mashed. This water is somewhat hotter than the target mash temperature, because some of the heat will be absorbed into the mash tun and the grain.
When we add the grain (probably at room temperature) to the hot water, the temperature of the mixture will be
lower than that of the water.
We want the temperature of the grain and water mixture to settle into the proper mash temperature (typically
around 150-156°F).
We need to calculate the correct temperature of the water so that the proper mash temperature is reached when
the grains are added.
This is the called the strike temperature, and is easily
calculated using the volume of brewing water, the weight and original temperature of the grain, and the desired
mash temperature.
Brewing software products, such as a program called ProMash, are available
to make this and other calculations trivial.
Some brewers insist on crunching the numbers in their head so that they can demonstrate knowledge of the
principles involved.
I am reminded of a story I heard some years ago in which a mother expressed concern to his teacher because
little Johnny was having trouble with long division using Roman numerals.
We recognize that this is silly because advances in arithmetic (Arabic numbers) made Roman numerals obsolete.
Advances in technology (calculators) made long hand division obsolete.
So why should one concern himself with obsolete concepts now that computers are widely available to take care
of such trivial details?
I guess when that comet strikes the earth and ends civilization as we know it, those of us that have smugly
relied on advanced technologies like this will no longer be able to homebrew.
We simply let the water in the mash tun settle and cool until it reaches the appropriate strike temperature.
When it does, we start adding the crushed grains, a little at a time so that all kernels are exposed to the
water, and no dry pockets are formed.
If we did our calculation correctly, the final temperature should match our target mash temperature.
If not, we can add a little hot or cold water (or use our recirculation system) to perform minor adjustments.
At this time, the acidity of the mixture is checked to ensure that it is at the proper value (typically about
5.2pH).
If the pH is too high, it can be adjusted by adding more gypsum.
(Gypsum is not itself an acid, but in combination with some of the substances in the grains, it promotes
ionization that results in increased acidity.)
If the pH is too low, then I suppose we could add caustic lye or some other nasty chemical.
Fortunately, this has never occurred in any of the beers I have brewed!
The mash is now left alone so that the enzymes can do their thing, converting the starch within the grains into sugars. We normally run the mash for 90 minutes, although all of the starch has probably been converted much sooner than this. The purist can perform a starch test by adding a drop of iodine to a small sample of grain taken from the mash tun. In the presence of starch, iodine will turn purple in color. When no starch is detected, the mash is complete.
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Once starch conversion has been completed, we raise the temperature of the liquid and grains to about 165°F and hold it for a few minutes in order to deactivate the enzymes. When this is done, it fixes the relative amounts of the simple and complex sugars in the brew.
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