Brewing Beer Essay Research Paper BREWING BEER

Brewing Beer Essay, Research Paper

BREWING BEER

People have been enjoying beer for centuries. Brewing beer started about 6000 years ago in ancient Mesopotamia. Back then, people brewed beer and baked bread similarly. These days, beer brewing has become a science.

Brewing beer is a complex biochemical process, part of which is fermentation. Fermentation of sugars and grains into ethyl alcohol is among the oldest known chemical processes used by man. There are four major ingredients used in brewing beer; water, malted barley, hops, and yeast. Sugar for the fermentation process is provided by the breakdown of starches in the hops and malted barley. Upon action by the enzymes present in the malted grains, the long chain starch molecules are broken down into simpler sugars which are fermentable and give beer its alcohol content. Longer chain sugars, called polysaccharides, are also formed. These sugars primarily give beer its body and sweetness.

The process begins with the preparation of the malted barley. Malted barley is a barley that has been allowed to germinate to a degree. Before the plant begins to rely on chlorophyll, the barley is dried and the rootlets are removed from the partially germinated seeds. During germination, the seed produces diastase enzymes that can convert starch into usable sugars. Trace elements necessary for the life cycle of yeast, such as Zinc and Calcium are also found in malted barley.

The malted barely is crushed to a suitable size for brewing, usually by using rollers. The purpose of this is to make the pieces small enough for the hot water to extract their flavor when it is added to make the wort. The wort is the mash, or mixture of assorted grains and water, that goes into the beer after it has been added to hot water and started to boil. Over grinding can make the barley very difficult to get out of the wort. Grinding or cracking the barley causes trace amounts of barley to enter the air and the process needs to be isolated from the vats used for fermentation.

The malted barley is mixed in appropriate proportions with hot water to begin preparation of the wort. Beer is made up of 90%-95% water.

The chemistry of the water used can effect both the flavor and the brewing efficiency of the beer. Excessive chlorine can greatly effect the other ingredients in the beer and can result in a harsh aroma and flavor. Boiling or filtration is often used to remove unwanted chlorine. The water used is usually hard. Hard water is water with a high content of minerals. A soft water can result in a milder flavor and aroma. Water hardeners such as table salt (NaCL) and gypsum (CaSO4) are sometimes added to soft water. Bacteria from the water can spoil the wort. This is usually removed through boiling.

The mixture of crushed malted barley and water is called the mash. The mash is put into a boiler and brought to a boil for around thirty minutes. The enzymes in the malted barley are reactivated by hydration and starch-to-sugar convergence is continued from germination.

The starch in the barley contains roughly 20% amylose and 80% amylopectin starches, which are very similar, but differ in molecular size and shape. Each contains up to a million glucose molecules tied together in a long chain creating a single starch molecule. Upon action by the enzymes present in the malted grains, malted barley and hops, diastase and amylase (also known as alpha amylase and beta amylase), the long chain starch molecules are broken down into simpler sugars, such as maltose (C12H22O11), glucose (C6H12O6), and maltobiose. These sugars are fermentable and give beer its alcohol content. Longer chain sugars, called polysaccharides, are also formed. These sugars primarily give beer its body and sweetness.

The grains are now extracted from the liquid. The end transparent liquid is a complex solution of sugars. Hops are now added to the boil. Hops are the cones or flowers of the female hop vine. The cones contain a resin called alpha acid that gives beer its bitterness flavor. Hops help to inhibit bacteria in beer, maintain flavor stability, and to retain the head of the beer. There are two main types of hops. Noble hops are low in bitterness and have a pleasant aroma and flavor. High-alpha hops have high bitterness but a less pleasant aroma. Today, the bitterness for each type of hops is rated by alpha acid units(AAU). It is calculated by the alpha acid percentage in the hops multiplied by the weight of the hops in ounces.

Continued boiling is necessary to extracts the hops’ bittering qualities. During this time the bittering resins dissolve into the mixture. Unwanted proteins coagulate and precipitate out the from the wort. The wort is now cooled and moved to fermenters.

Fermentation is the all important step of brewing. The initial stage of fermentation is an aerobic process, therefore it utilizes the free oxygen in the mixture. Yeasts derive energy from oxygen during its respiration stage. Oxygen is most important at this initial stage of the brewing process called the yeast’s respiration stage. If oxygen is not present during respiration, fermentation will not continue. The correct amount and type of yeast is added to the wort. During fermentation, yeast goes through its life cycle from beginning to end. It is in this stage that the beer gets its alcohol content and its flavor.