Michael Mosher - Brewing Science: A Multidisciplinary Approach

Department of Chemistry and Biochemistry, University of Northern Colorado, Greeley, CO, USA

Department of Physics and Physical Science, University of Nebraska at Kearney, Kearney, NE, USA

The scientific method is a process of thinking about problems. The method is outlined in Fig.. Brewers, or anyone for that matter, that use this process methodically arrive at the answer to a problem or develop a law or theory based on observations. This is the same way of thinking about the world around us that scientists use everyday. An example helps guide us to understanding the scientific method.

A brewer starts with an observation. For example, suppose they notice that a recently brewed batch of beer tastes a little like buttered popcorn. The brewer would then develop an educated guess, called a hypothesis, which would attempt to explain the origin or cause of the off-flavor. For example, the brewer may hypothesize that the temperature of the water used in the process was too hot. Then, the brewer would perform an experiment to try to eliminate that flavor, in this case by reducing the temperature in the next batch of beer. After making more observations (tasting the beer, running laboratory analysis of flavor components, etc.), the brewer would then compare those results to the original hypothesis. If the observations did not fit the original hypothesis, the brewer would modify the hypothesis and return to the brewery to perform another experiment. Then, they would modify or recreate the hypothesis and test it out in the brewery. This cyclical process would continue until the hypothesis did not need modification after repeated experiments. The brewer would have found the answer to the observation and know what to do if that situation ever arose again. When the hypothesis is proved in such a manner, it can be called a law or a theory.

A law is a tested and proven hypothesis that explains the initial problem. Laws do not explain why the problem occurs, but simply what happens if another thing is done. In our previous example, the brewer may eventually discover that if the serving tap for the beer was cleaned immediately before use, the off-flavor would disappear and arrive at a law: Cleaning the beer tap removes the buttered popcorn flavor in the beer.

A theory, on the other hand, is a tested and proven hypothesis that explains why something happens. Theories are the most definitive statements that can be made. They are not just statements that identify the outcome of a particular step in the brewery. They predict the outcome by providing a detailed explanation of why that outcome occurs at any level of observation. To a brewer, and any scientist, a theory is the best statement that one can have about a process. In our example, the brewer may develop a theory that explains that bacteria in the tap line cause the off-flavor.

We will use this method as we explore issues surrounding brewing science. We will learn the existing theories about the science and use the scientific method to suggest additional directions that the brewer could use to advance their understanding of the process. Let us start by examining beer and brewing from its origins to the present day.

The first recorded recipe

The first beers were most likely made in Mesopotamia, the cradle of civilization, well before the eighteenth century BC. We know this because references to beer parlors were noted in the Code of Hammurabi. This code of laws was written around 1772 BC by the sixth Babylonian king, Hammurabi. The code explained the laws for the operation of their civilization; the phrase we know as an eye for an eye comes from these laws. Beer was noted in many places within the laws as well, hinting that beer predated this time enough to have pervaded society by 1772 BC.