Alcohol - part 1

So today, I'm going to be discussing something near and dear to many of our hearts (and livers): alcohol. Specifically today, I will be discussing the process by which alcohol is most commonly made and I will go into some of the history of it. Reaction is entirely dependent upon this little reaction here:

Now this just looks like a bunch of nonsense for many people, I realize. We've got some letters and numbers and somehow glucose (sugar) plus enzymes (yeast) gives us ethanol (alcohol) and carbon dioxide (the stuff you breathe out and plants use). So let's simplify this a bit. Basically yeast are little tiny, very robust lifeforms and they are incredibly ancient. They're classified as fungi (yep, like mushrooms) and are unicellular organisms and humans have been using them for thousands (if not tens of thousands) of years to make bread and alcohol. Yeast eat carbohydrates (so things like sugar) and they make alcohol and carbon dioxide from it. So yes, alcohol is basically yeast poop, but that doesn't mean it can't be delicious.

Now that we've discussed the basics of how fermentation occurs, let's get into the nitty-gritty about how people utilize this process to create drinks like beer and wine. In chemical engineering and process design, there are essentially two main kinds of reactors (with some exceptions). These are batch and flow reactors. A batch reactor is a reactor where you add all your components, seal the vessel and then wait for the reaction to occur. You may altar the heat over time, but essentially no mass is going in or out during that time period. A flow reactor is different because mass is moving in and out of the reactor at any interval in time. The first step in creating alcoholic beverages relies on batch reactors and if we wanted to make our drinks even stronger we would use a flow process to distill our drinks (see my next post on distillation and an instructional post on making wine). Now in any brewery or winery, they're going to start with some kind of plant matter or fruit. Beer uses hops, barley, and other grains. Wine uses grapes and occasionally some other flavors. This plant matter provides the starting material we need for making alcohol because it has the one thing yeast love to eat: sugar. So we take our carbohydrate-rich plant matter and we dump it into a big tank. Great, Now what? We can't just add yeast and have alcohol so generally, we add water to act as a house so the yeast can reproduce and move around to find the sugars and convert them into alcohol. So one we've added all our raw ingredients (fruit, grains, or any other flavorings we want, and yeast), we close up the vessel (often large stainless steel containers for beer and wooden casks for wine). We have to be safe though, yeast produce carbon dioxide when they eat sugar and carbon dioxide is a gas. This increase in pressure can cause an explosion if not properly vented. In the production of alcohol beverages, an air-lock is used. This is a device that lets out air produced inside, but prevents air from the outside from getting in and ruining the batch. Now we wait anywhere from a few months to a couple decades before we open up the vessel. Inside we'll find our alcoholic beverage if everything went as planned and we can enjoy our drinks.

So what happened to those yeasts? Well basically, they ate so much sugar and produced so much alcohol, that they basically died or went dormant because there either wasn't enough food left or their environment had too much alcohol in it (usually maxing out around 15% by volume). This alcohol is also what helps keep other bacteria and fungi from growing and ruining the drink and thus this is why alcohol was historically and still is a great way to preserve beverages. Take for example, Irish cream, a cream based alcohol drink. The presence of alcohol can prevent the dairy inside from spoiling near indefinitely where normally the cream would go bad in a week or two on it's own even with refrigeration. Some breweries and wineries choose to filter out the dead yeast from their drinks, but other ones choose to leave them in, but no worries, they're completely safe to consume and some wine and beer aficionados like the taste the yeast presence generates. Now what if we want to drink something stronger? You know, you're rums, vodkas, tequilas, and irish creams? Then we have to do something called distillation, so stop by next time and I'll explain how that happens! Until then, keep enjoying your drinks!