The grains (barley, wheat, rice, corn, oats, rye, etc.) are much the same as those that are used to make many breakfast cereals. The barley and wheat must undergo a malting process before they can be used to make beer (the others do not). The malting process simulates grain germination, which metabolizes the natural grain sugars (called maltose), which is what the yeast feeds on during fermentation.
The hops provide beer with piquant aroma, a variety of flavors, and a delicate-to-intense bitterness that balances the sweetness of the malt.
During fermentation, yeast consumes the sugars derived from the malted grain and excretes ethyl alcohol and carbon dioxide in return.
Considering that beer consists of up to 95% water, the quality of the water is of great importance. Depending on its source, water can have varying levels of mineral content, and this minerality can have a significant effect on the taste of the beer.
What are the three parameters by which all beer styles are measured?
All beer styles are measured and categorized by their color, bitterness level, and alcohol content.
Beer color can range from pale straw to opaque black, depending on the style. This color can be measured on the Standard Reference Method (SRM) scale, anywhere between 1 and 40.