THE CHEMISTRY AND BEER HISTORY

Beer has played an important role in chemistry and biology both from a historical and from a technical point of view. Although many mistakenly attribute the discovery that beer yeast is a living organism to Louis Pasteur (1822–1895), it was reported nearly simultaneously by Charles Cagniard-Latour and Friedrich Traugott Kützing in 1837, and Theodor Schwann in 1839.

This observation was strongly attacked by the leading chemists of the time, including Justus von Liebig (1803–1873). The mocking, dismissive tone of their attack seems more characteristic of political talk radio of our own time than scientific discourse.

Liebig was eventually driven back from the position that yeast are not living, but to his death he opposed the idea that they are responsible and necessary for alcoholic fermentation. This bitter and fruitful scientific controversy over the nature of fermentation continued between Liebig and Pasteur, ushering in the modern age of biology.

Liebig held that fermentation was a nonliving process in which the decaying matter contributed its energy to the breakdown of sugar. Pasteur held that fermentation was a part of the life processes of the microorganisms that were involved with it. The results and arguments of both men were hijacked by followers of the doctrines of vitalism and mechanism.

The vitalists believed that the processes of life could never be explained by the laws that govern ordinary matter. The mechanists believed that living systems follow the same laws as nonliving systems.

Now, 150 years later, we can say that Pasteur was right that all the fermentations that he, Liebig, and anyone else observed were caused by microorganisms. Liebig was right that fermentation is an ordinary chemical process that could, under the right conditions, occur without the participation of living cells.

Eduard Buchner (1860–1917) proved this in 1897. Buchner ground up yeast in the presence of abrasives and squeezed out fluid through a cloth. When sugar was added to this fluid, carbon dioxide and alcohol were produced, exactly the same reaction as occurs in live yeast cells.

Buchner won the Nobel Prize in chemistry in 1907, the first awarded for a biochemical discovery. In retrospect it is clear that Liebig and Pasteur did not allow themselves to be governed by doctrines like vitalism and mechanism. Pasteur was the first person to apply the principles of microbiology, a field he helped found, to the brewing of beer.

Many advances in chemistry were driven by the needs of the beer industry. These include measurement of temperature and of specific gravity. The Carlsberg Laboratory, set up in Copenhagen in 1875 (one year before Thomas Edison’s laboratory in Menlo Park) as an arm of the Carlsberg brewery, was the site of several important discoveries.

Emil Christian Hansen (1842–1908) was the first to raise up pure cultures of yeast (or any microorganism) on an industrial scale. The first reliable method of protein analysis was put forward by Johan Kjeldahl (1849–1900). The concept of pH, which is central to water chemistry, was introduced by S. P. L. Sorensen  (1868–1939). The Guinness brewery in Dublin gave us the statistical method called Student’s t-test, invented by William Sealy Gossett (1876–1937).

CHEMICAL BALANCING EQUATION BASIC INFORMATION AND TUTORIALS

Basic chemical equation balancing.

If you carry out a chemical reaction and carefully sum up the masses of all the reactants, and then you compare the sum to the sum of the masses of all the products, you see that they’re the same.

In fact, a law in chemistry, the law of conservation of mass, states, “In an ordinary chemical reaction, matter is neither created nor destroyed.” This means that you neither gain nor lose any atoms during the reaction.

They may be combined differently, but they’re still there.

A chemical equation represents the reaction, and that chemical equation needs to obey the law of conservation of mass. You use that chemical equation to calculate how much of each element you need and how much of each element will be produced.

You need to have the same number of each kind of element on both sides of the equation. The equation should balance.

Before you start balancing an equation, you need to know the reactants and the products for that reaction. You can’t change the compounds, and you can’t change the subscripts, because that would change the compounds.

So the only thing you can do to balance the equation is put in coefficients, whole numbers in front of the compounds or elements in the equation.

Coefficients tell you how many atoms or molecules you have. For example, if you write 2 H2O, it means you have two water molecules:
2 H2O = H2O + H2O

Each water molecule is composed of two hydrogen atoms and one oxygen atom. So with 2 H2O, you have a total of four hydrogen atoms and two oxygen atoms. In this section, I show you how to balance equations using a method called balancing by inspection (or as I call it, “fiddling with coefficients”).

You take each atom in turn and balance it by inserting appropriate coefficients on one side or the other. You can balance most simple reactions in this fashion, but one class of reactions is so complex that this method doesn’t work well for them: redox reactions.