Fermentation has two critical pieces: An organism, and its food. In the making of beer, the organism is (usually) yeast, and the food is (mostly) sugar derived from grain.
There are several ways for the home brewer to get sugar from grain. In All Grain brewing, the brewer fills a vessel like a cooler with a given number of pounds of grain, then steeps it in a particular volume of water at a given temperature for a set period of time. There are many variations on this step, which is called “mashing.”
“But wait!” You may be saying. “If I steep barley in water, I get something like cooked rice! How are brewers getting sugar from grain?”
Great question! A grain like barley, wheat, rice, corn, and so on, is a seed. Its purpose is to fall to the ground, wait for appropriate conditions, and then absorb a ton of water (relatively speaking) in order to shatter itself open and send a rootlet down into the dirt and a shootlet up into the sky.
That process requires a lot of energy, so various enzymes activate throughout the germination process. They convert the carbohydrate energy stored in the seed into sugars that the germinal plant can access. From the annual plant’s point of view, it’s an adaptation that lets it send its offspring into a future it won’t see.
When a home brewer mashes in an All Grain batch, they steep (mostly) malted grains, that is, grains that have been germinated to the point where their sugars – and the enzymes that convert starch to sugar – are most available, then dried in a kiln. Very few home brewers undertake this step, as it requires days of babying the grains, precise temperatures, and a lot of space. Riverbend Malt House, in Asheville NC, has a really informative website if you’d like to learn more about malting.
Many commercial malters continue to process the malted grains after kilning. They grind them, mash them in to extract the sugar from grain, and then evaporate them to produce liquid malt extract, the syrups that many home brewers use in their brew kettles, and dry malt extract, which is the powdered form of the grain sugars.
So home brewers have a choice – purchase malted grains for mashing, or purchase malt extract that can go straight into the boiling kettle. Both can produce delicious and award winning beers, though All Grain brewers are rightly proud of their extended craftsmanship. Don’t let anybody push you around though. Plenty of great beers are made in kitchens using cans or bags of extract, and for those lacking the space, time, or interest to brew All Grain batches, extracts are ideal.