Notes from Byron Burch's Brewing Quality Beers:
Malts, along with sugars, provide sugars for yeast to convert into alcohol.
Malts also provide some of the body, or "full mouth feel" of beers.
Sugars serve primarily to raise the alcohol level while doing little for flavor or mouth-feel.
If you prefer full-bodied, richly flavored beers, you will most likely prefer those with a high malt content, without too much sugar (aside from priming sugar, for bottling).
Most home brewers use the term "malt" in reference to malted barley.
The grain is allowed to partially sprout in the malting process. It is then kiln-dried - at lower temperatures for light color, at higher temperatures for dark color. Malting begins the process of turning starches in the grain into fermentable sugars. The "mashing" procedure completes the process - the grain is crushed, water is added, and the mixture is steeped at specified temperatures for specific amounts of time.
As an alternative to malting grains yourself, concentrated extracts of barley malt are available in syrup or powdered form. These have been concentrated after the malts have been mashed. The syrups are often called "malt extracts" and the powdered form, "dry malts."
Some recipes call for adding malt or other grains to provide added color or complex flavors. This first step will be "Simple Infusion Mashing," (I'll address this process in another post) unless you're using black grains (such as Chocolate Malt, Black Patent Malt or Roasted Barley), which are added directly to the boiling kettle halfway through the boil.
Pale Malted Barley - British vs. American
British pale malt is darker, giving beer a golden color.
Domestic pale malt is "properly" called Lager Malt.
Lager Malt is extremely light in color, crisp and dry in flavor. Advanced brewers use this as the base malt for making light, delicately flavored lagers.
Either Lager or Pale Malt can be used in small amounts to add body and flavor to any type of beer, or to slightly raise the Specific Gravity of a wort.
Mild Ale Malt -
has a bit more color than pale malt, and can be substituted for pale malt when making brown ales.
Munich Malt -
aromatic malt that gives beer a gold to amber cast, depending upon amount used; may be substituted for Pale, Lager, or Crystal Malt in many recipes
Wheat Malt -
in small amounts, will give beer a light, clean taste; good for head retention
Crystal (caramel) Malt -
kiln-dried at higher temperature, giving it a darker color and caramelized flavor; used in small amounts for adding color and flavor to amber, brown and dark beers
Black Patent Malt -
very dark and strong flavored; used in dark beers and stouts; all the starch has been burned out in the kiln, so it is added to the boiling pot whole; when experimenting with this malt, start with a small amount, increasing the amount in successive batches until you find a palatable amount; can yield good results, but can easily be overdone.
Roasted Barley -
similar to Black Patent, but roasted without being malted first; used in Irish Stouts
Chocolate Malt -
slightly lighter roast than Black Patent or Roasted Barley; smooth flavor suitable for porters
Dextrine Malt (cara-pils, or cara-crystal) -
contributes mostly unfermentable dextrins to a mash; increases full mouth feel, smoothness, sense of sweetness; neither a sugar nor a starch
To experiment with dextrin powder, use 1-2 oz per 5 gallons with lighter, more delicate beers, and up to 8 oz in heavy, dark beers.
Dextrin powder is added during the boiling of the wort.