Science of Brewing


As a brewer prepares to brew beer, they have to take into consideration the numerous factors involved.  One of the bigger factors in the early stages of beer brewing is the nitrogen level.  According to Karl Ockert, “free amino nitrogen (FAN)” levels determine “yeast growth, high diacetyl levels, [and] high beer pH” (Ockert 9).  The typical nitrogen level is between 15 mg/100 ml and 35 mg/100 ml, and this can be controlled through the choice of malt (Ockert 10).  Due to modern day technology, breweries can actually check the levels to make sure everything is correct. The large breweries must check the chemical balance often so every batch tastes the same, while small scale breweries don’t have to worry as much about performing checks since the taste doesn’t need to be exactly the same. Large-scale breweries also perform checks more often because they usually have enough spare resources to check FAN levels for a cheaper price.

Another factor in brewing is the oxygen level in wort, the basic ingredient for beer.  Wort is the result of the mixing grains and water, then heating the mixture up until enzymes break down the starches into sugars.  After wort is cooled, dissolved oxygen (DO) acts as a catalyst for fermentation and more yeast production.  In doing so, DO indirectly affects the taste of beer.  Dissolving too much oxygen in wort can be detrimental to beer because yeast production will get out of hand and cause the beer to have bad taste.  Brewers can control or experiment with beer taste just from the oxygen level in beer, ranging from “0 [ppm] to more than 40 ppm” (19).

One last factor in beer brewing is the amount of organic acids available in the beer.  These organic acids contribute to the pH of beer, which plays a factor in controlling beer hazing, how fast maturation happens, or how easily beer can be contaminated by bacteria.  It also plays a part in beer flavor, as a low pH level usually means the beer flavor won’t last as long (24).  There are some ways to control beer pH to a favorable level.  These ways include “lowering brewing water alkalinity, lowering wort pH, using low protein malts,” and more (25).

In the older days of beer brewing, brewers didn’t have the technology to monitor the FAN, DO, and pH levels.  It was because of the lack of technology that they expected they would occasionally brew some faulty beer.  However, modern day technology allows the brewer to monitor the FAN, DO, and pH levels.  With this technology, the brewer is able to alter the way beer tastes, looks, or even how long a beer can last for.

In order to prepare the ingredients for beer brewing, certain precautions need to be considered.  One of these precautions is building a fermenting cellar fit for yeast fermentation. These cellars must allow for easy access for cleaning to prevent mold and bacteria from growing and ruining yeast.  Modern day cleaning supplies makes this task relatively easy to accomplish, so brewers only have to worry about constructing the cellar out of material that can handle the constant cleaning (67).

Another preparation is the refrigeration of lager.  Modern day brewing is fairly simple with the use of a refrigerator.  However, the older days required the storage of lager during the cold, winter days.  One method was to build the cellar underground and use ice to help cool the cellars.  The cold air would sink and the warm air would rise out of the cellar (74).