Fermentation 3/12/19

By Richard E. Bleil

“Zymergy” is the name of the science of fermentation. I know this because my mother bought me a collegiate dictionary back when they were selling collegiate dictionaries. It was on sale, because the copyright year was misprinted. Anyway, the very last entry in the dictionary was “Zymergy”, the science of fermentation.

Today, our president “tweeted” a comment from his favorite “news” show, claiming that global warming is “fake news”, and that carbon dioxide is “a basic building block of life”. Well, that may well be true, but too much of a good thing is still bad.

This got me to thinking about drinking. Heavily. And the fermentation process.

Animals like to get drunk too. When fruit rots, fermentation is a natural process in which microbes convert sugar to ethanol, the active ingredient in alcoholic beverages. This ethanol is the waste byproduct of the microbes, much as humans produce waste byproducts when we consume food. The difference is that, thanks to the development of the Romans, we can safely flush our waste byproducts away. The microbes live in theirs, and much like our waste byproducts are toxic to us, ethanol is toxic to the microbes. We would die if we tried to live in a septic tank, and the ethanol produced by the microbes eventually kills the microbes.

One of my favorite seasonal treats are the apple cider products that become so prevalent and affordable in the fall. I will frequently buy containers of apple cider, but, living alone, I don’t always get to them as quickly as I should. One year, I had forgotten about one such container, and sure enough, the container was pressurized and bloated by the time I got to it. Yep, it had fermented (one of the byproducts of which is carbon dioxide, hence the bloating). And, yes, I did drink it, but even for a lightweight like me, it had no noticeable side effects. I didn’t even get any work done.

The problem is that the alcohol kills the microbes at an alcohol content too low for us humans to be content. (See what I did there?) This lead to a variety of ways to increase the alcoholic content of our beverages. Earlier I had written a blog about how colonists used to increase alcoholic content by freezing out water and where the term “proof” arose. Today, of course, distillation is commonly practiced to create the highest alcoholic content beverages. Distillation simply means the beverage is heated, the alcohol (and other components) boil off, the vapors of which are captured and recondensed by cooling into a higher purity liquid. Whiskey, rum, gin, brandy and vodka are examples of distilled alcoholic beverages.

What a lot of people do not know about is called an “azeotrope”. When you boil your solution, you will always boil a little bit of the solvent (water) off with the solute (ethanol). Eventually, you reach a point where you can no longer purify a substance because the amount of water will always boil off in the same ratio. This is called an “azeotrope”, and for ethanol occurs at about 95% ethanol (190 proof). There is a well-known alcoholic beverage that is sold as 190 proof, and this is why it has that extra 5% water. The water can be separated further through the use of expensive and messy chemical techniques (such as the addition of a desiccant) which then has to be separated in and of itself, but using distillation alone, 190 proof is the strongest possible.

Alcoholic beverages are fermented at ideal conditions to keep the microbes alive as long and as productive as possible. Undistilled beverages, such as beer and wine, are typically at the percent alcohol they are because this is the best the microbes can do. For many years I assumed that the difference between red and white wines was if they used different kinds of grapes, but actually it depends on the “mash”. Red wine mash includes the grape skins and seeds, whereas white wines separate out these components. “Sparkling” wines capture the carbon dioxide from the fermentation process, or undergo a secondary fermentation to create the carbonated mix.

There is kind of a combination of the two, distilled and undistilled. Fortified wines, for example, are undistilled, but are “fortified” with added ethanol. Port, Sherry and Vermouth are examples of such drinks.

In France, by law, the wine is named for the region in which the grape is grown. Whether or not this custom is respected here in America is hit or miss, but it is why there are excellent sparkling white wines from France that are far less than Champagne yet barely distinguishable, if at all. Champagne comes from the Champagne region of France, and there are sparkling white wines from France grown literally across the street from the legal definition of that region, and thus cannot be legally called “Champagne”. There is no such thing as “American Champaign”, since the Champagne region is in France, but you will find some American companies producing excellent sparkling white wines respecting that naming convention, which is something that I do appreciate. Brandy ad Cognac are another example. I’ve never been able to distinguish (although I admit my palate is not refined) between Brandy and Cognac. It turns out they are produced with the same grape and very similar processes, but Brandy is made in America and Cognac comes from the Cognac region of France.


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