Brewing Course – Round Two
Round two of brewing at Erfurt’s finest microbrewery occurred on a beautiful Sunday. Once again, our goal was to create a fantastic, yet simple, porter. With a crew of six students, the class began with the task of milling the grain.
As this Sunday course had a dual purpose – brewing beer and baking bread – this would be a good point to discuss the theory of malting and milling.
Malting
Just like wheat grain is the base ingredient for bread (though other grains are also used), barley is the base ingredient for beer (though other grains are also used). The main difference is that for efficient alcohol conversion, the barley must be malted prior to use.
Malting is the process in which the barley grain is tricked into germinating and then expertly heated to stop a plant from growing. The act of germinating requires a lot of energy that is all stored in the endosperm in the form of starch. The heat and moisture used by the malters triggers enzymes in the grain to release this store of energy. When the growth has reached its optimal point, the malter ends the growth with heat. The accessible starch is now available to the brewer.
In the mash, the brewer will then convert these starches to fermentable sugars through the amylase rest periods. Know that unmalted grains are also often used as adjuncts, which are not intended to add fermentable sugars, but rather unfermentable flavors. The amylase rests during the mash process also further break down cell walls while converting the starches to sugar. This process determines the flavor and potential alcohol content that the grains will contribute to the final beer.
The heating of the grain to stop further germination (and starch consumption) also plays an important role in color and flavor. A lightly kilned grain will be perfect for a crisp, light, clear pilsner; a heavily kilned grain will toast some of the sugars, caramelizing them – this will give the final beer a darker color with hints of chocolate and coffee. This latter group was used sparingly in the porter brewed; a little bit goes a long way in brewing.
Milling the Grain
The malted grain, while loaded with starch, still contains a pretty impervious hull (or bran). In order to gain access to that energy, the grain is milled. The finer the grain is milled, the better the hydration of the starches contained (leading to better efficiency). However, a very finely milled grain will also lead to the forming of a dough (similar to bread), from which the wort cannot drain. This is referred to as a stuck mash.
To avoid a stuck mash, the hull plays an important role in ensuring a strong drain bed. Furthermore, some brewers include rice hulls to further promote efficient draining of the wort from the grist bed.
The milled grains are then processed through the chosen mash process (single infusion process, a multiple infusion process, or a full-out decoction process). This is then sparged through batch- or fly-process. All of these techniques are worthy of exploration in later posts.
Brewing 100 Liters of Beer
The process for brewing large batches is the same amount of work as small batches – it is only the equipment that is different. Working with large quantities of grain, good amounts of hops, and great volumes of water requires big devices. It also requires use of a huge fermentation vessel.
