There is a very wide variety of grains, cereals and extracts that can be used for the brewing process. Barley itself has favorable attributes for brewing, such as susceptibility to mold and fungus, plus its high percentage of convertible sugars, and that is why that it is the most widely used grain around the world.
Barley is not alone, however, in the brewing process. Wheat is a popular front runner as far as use around the world. You may have noticed that Budweiser uses rice as one of its ingredients. They claim its adds crispness to the finish. In Africa sorghum is used. Other comparable ingredients that are readily available include maize and oatmeal. These cereals have different properties that can be used to provide cheaper sources of extract, add color, and can also prolong the shelf life of the packaged product.
Style and Preparation
Grains and cereals come in a few different forms; Raw, crushed, flaked, and of course as an extract. When deciding between the different preparation types of the grains, it's important to understand what they provide for the character of the beer. For example, brewing with raw grains is done on a massive scale, however the starch modification during the brew process is radically different than with using the malted varieties. Furthermore a great deal of attention and detail go towards the malting process which acts as a huge filter for ensuring that the finest ingredients make it into the home brewers hands
The use of raw grains is generally done on commercial scales in order to cut out the middle man, the maltster. Although many of the large breweries will malt their barley on the premises, along with have their own power plants. Unprocessed barley is cheaper than barley, and therefore in a lot of cases is used in some capacity with the malted grains to make the final beer. The malting process, in essence, prepares the grain so that it is ready and eager for the brewing process. Without the modifications steps the grains are a little more volatile and a little tougher to control the flavor and alcohol production. Generally microbiological enzymes such as beta glucanese, alpha amylase, or neutral protease are added to help with the modification processes.
For the homebrew, working with raw grains is not needed. The enzymes are difficult to perfect, and the available malts on the market provide enough high quality options to keep you brewing new masterpieces every time.
Malted grains are those that have gone through the steeping and germination process. From a home brewing perspective, there is a lot to be gained by working with the malted grains. First, the maltster has already done the quality comparisons for the raw grains, and hopefully selected the finest. From the time the barley is harvested to the time it makes it to the steep tank there are many things that can damage the grains including improper moisture, pest invasion, and mold and fungus. Every step of the process has favorable conditions that help to protect the grains, as well as ensure stability for the shipping or storage.
Steeping the Grains
Steeping is the first step in the malting process. This step prepares the grains for germination by soaking in water. The grains are placed into steep tanks, which are conical cylinders, where a constant temperature can be maintained. The grains quickly soak up the water through the micropyle or through cracks in the husk. The water is drained after 18-24 hours, providing air-rest for the grains. After several hours, the tanks is filled again for another cycle. This continues until the grains have an acceptable moisture content.
The Germination Process
The germination process uses a combination of air and water to both aerate the grains and at the same time maintain a constant moisture level. This is done by spreading the grains across a pourous surface that allows air to flow. The air is humidifed before it makes it to the grains, and over time the grains produce an embryonic shoot. When the shoots of the grains get to a certain length, the germination process is considered complete. This is done in approximately 3-5 days.
Kilning the Grains
Kilning is the last step that removes most of the moisture and brings out the color and the flavor of the grains. Prior to this point, depending on the beer, the grains will have varying germination levels. Ale malts for example will have a higher modification than lager malts. During kilning these different types of malts also vary in the time and temperature that are used. Kilning is achieved by passing warm air through the grains at a relative humidity within the kiln. As the rate of dissipation of the water from the grains changes over time, so does the temperature and humidity of the water over time. As the lower grains in the bed begin dry more rapidly, the heat is increased and the air flow is reduced. This repeats, until the final stages which vary for the different malts in order to achieve the proper color and ending moisture levels at around 2-5%.
Liquid and Dry Malt Extracts
The Malt Extracts then take this a step further, and is similar to the actual brewing process. The maltsers grains are milled or ground up, mixed with water, and heated up. The resulting wort is filtered and is then ready for the evaporation process. The evaporator extracts the moisture using heat and ends when the desired moisture level is achieved. These extracts are commonly used in commercial foods as well as beers.