Реферат: How To Make Beer Essay Research Paper

How To Make Beer Essay, Research Paper

The first and most important step in brewing is cleanliness. The first step in the actual brewing process is malting. Malting is what is done to the barley to prepare it for brewing. The steps of the malting process release the starches that are contained in the barley, while minimizing haze and off-flavors. Grain is allowed to soak in 60. F. water to increase the moisture content of the grain to about 40-45%. The grain is usually spread out on the floor of the germination room, or some other container. These grains are kept at a temperature of about 60. F. The germination is complete when the sprout has grown to about 3/4 the length of the grain and the hard part of the grain, or the shell, has turned soft. The goal for germination is for the starches within the grain to break down into shorter lengths. At this shorter length stage, the grain is called green malt. Kilning is the next stage after the grains have sprouted. Kilning is the process of drying the grain in the kiln where the temperature is slowly raised during the 30-35 hour period. After kilning, the result is finished malt, with soluble starches and developed enzymes. These grains each have a different and distinct flavor depending on how long they are cooked in the kiln. After the malting, the grain is ready for milling. Milling is the cracking, and crushing of the grain. This procedure is controlled carefully so as to break the grain while keeping the husk as large and as intact as possible. Milling allows the grain to absorb the water it will be mixed with later as the water will extract sugars from the malt. The malt will now be mixed with warm water in the mash tun. This vessel holds the grain and water mixture for a period of time. Two important things will take place in this step. One is to break down proteins to the more soluble and usable amino acids, providing food for the yeast and foam for a nice head on the beer. The second thing is to break down the starch to simple sugars so yeast can convert them to alcohol and carbon dioxide. Mash filtration consists of filtering the converted mash by gravity or pressure in a lauter tub or mash filter to separate the insoluble matter in the malt from the soluble sugars and nitrogen compounds. The sugar liquid recovered is called wort, pronounced wert, or sweet wort. Boiling the wort is best but is also the most expensive method, Microbreweries generally use this method. The sweet wort is boiled and treated with hops in the brew kettle in a planned schedule, usually somewhere between 30 and 90 minutes. The boiling has many effects: all bacteria are killed, it produces color and flavor compounds, the so-called browning compounds, from the malt and sugars. Boiling the wort extracts bitter and aromatic flavor compounds from the hops, and volatilizes most of the harsh hydrocarbons. It sterilizes the wort and stops all enzyme action. The boiled wort is strained to remove the hops and then transferred to a holding tank called the hot wort tank. The insoluble matter, called trub, is centrifugal separated in the whirl pool tank. The wort is now passed through a heat exchanger that rapidly cools the liquid. Cooling is necessary in order to add the yeast. Yeast is unable to ferment or grow at high temperatures, so cooling the wort to about 70.F is needed. Here is where hydrometer readings are taken to record the amount of sugar in the wort by measuring the density of the liquid. This is called the specific gravity. The specific gravity is used in determining the alcohol content of the finished beer. The more sugar there is, the more dense the liquid. The higher the specific gravity, the more sugars there are available for fermentation, producing more alcohol. It is here in the fermentation tank that the yeast changes the sugars into alcohol over a period of days or weeks, depending on the style of beer being brewed. Ferment is taken from the Latin “to boil”. Watching the yeast in active fermentation, one can understand the reason the word is used. Fermentation begins with pitching, or adding the yeast to the cooled wort. Pitching can only be done when the wort is at the proper temperature, around 70.-80.F. Fermentation temperatures also can vary depending upon the type of yeast used. Fermentation temperatures for ales are 55.-65.F., while for lagers 40.-55.F. is used.There are different types aging techniques. Of these are Rhu, Lagering, Secondary Fermentation or Krauesening. Rhu, which means, rest, is usually a short period of two to seven days in which the beer is cooled and the yeast that did not settle in the fermentation vessel now will settle. This results in a reduction in yeasty flavors in the beer and makes filtration easier. Lagering, from the German, means, to store. This is a longer period, seven to fourteen days, during which the temperature falls more slowly, reducing yeasty and sulfur flavors. The beer also clarifies and mellows. Secondary Fermentation usually takes ten to fourteen days and involves transferring beer out of the fermentation vessels before its yeast has completely fermented the sugars, and allowing the rest of the fermentation to continue cool and slow. Krauesening is a delicate process in which fermented beer, after being transferred to another vessel, is mixed with young beer that has just started to ferment. (Jackson) Beer will naturally tend to turn cloudy when it is cooled to temperatures near freezing. To prevent this, an extract of the papaya, papain is often used to prevent this. The beer is then either filtered, centrifuged, or both to remove any yeast and insoluble matter. Diatomaceous earth, siliceous skeletons of ancient marine organisms, or cotton pulp is used as a filtration medium. Some beers are filtered twice. Beer must be either pasteurized or sterile filtered to protect it from the continued growth of any stray yeast. The beer is now ready to be filled into bottles or kegs.