Investigating the intricacies of beer brewing

A field of Barley, the main component of beer that is fermentable.

The Brewing Process

Every beer, no matter how diverse, is made from the same process. The four basic ingredients in beer are water, malt, hops, and brewing yeast. These components initiate chemical processes that can be systematically altered to achieve a brew of consistent and predictable quality. Prior to brewing, the barley used needs to be prepared by steeping it in water and allowing it to grow for several days. The barley is then dried using a kiln. A mill is used to break down the barley to facilitate the reaction between the enzymes and starch molecules. These grains are heated in water until enzymes break down the starches into a sugar solution called a wort. The hops are subsequently added to the brew kettle to add bitterness and flavor to the beer. This mixture is cooled to a temperature where the yeast can be added to a fermentation tank. Here, the beer is left to ferment in which the sugars are converted into alcohol. Finally, the fermented beer is transferred to a maturing tank where it remains for a certain amount of time before being filtered and bottled. The amount of time spent in the maturing tank depends on the type of beer being created along with the temperature and pressure of the tank. In general, most beers are in the maturing tank for 2-4 weeks prior to being ready for consumption. 

Malting

Prior to the barley grains being heated in water, it gets malted. This process called malting involves toasting the grain to create flavor compounds depending on the kind of beer you are trying to make. For example, malting can produce burnt almond, smokey, and caramel flavors. Equally important to this process is temperature. When the malted grains are heated in water, it is imperative to control the temperature since this ultimately affects the taste of your beer. Specific enzymes that break down the starches function in low heat, whereas other enzymes are only activated at elevated temperatures. These different enzymes are responsible for giving a particular beer its unique taste.

Compounds Contributing to Beer's Flavor

India pale ales (IPAs) contain alpha acids and beta acids that provide IPAs their unique flavor. The primary alpha acid in beer is called humulone, which has a soft bitter flavor that makes beer taste hoppy. Beta acids, like lupulone, take longer to contribute their flavor to beer; therefore, these acids are mostly found in aged brews and are important in producing beer's aroma.

Chemical structure of humulone, an alpha acid that contributes to beer's bitterness.

Chemical structure of lupulone, a beta acid that mainly provides beer with its unique aroma.

When hops and worts react with each other, essential oils are created that are crucial in providing unique flavors to beer. Some of these oils are myrcene, terpene, and humulene which are found in pine trees, citrus, and hops, respectively. There are 22 different essential oils known to contribute to the aroma and flavor of a beer.

Like mentioned before, yeast ferments beer by eating up the sugars and converting them into alcohol and carbon dioxide. Some beers, like stouts, have carbon dioxide replaced with nitrogen gas in order to provide a creamier, thicker taste. Nitrogen gas is much less soluble in water than carbon dioxide, which translates to fewer bubbles in the beer. Nitro beer is a relatively new innovation that has about 70% nitrogen gas and 30% carbon dioxide. The popular beer, Guinness, is typically credited as developing this notion of infusing beer with nitrogen gas.