When I introduce fermentation to my students, I always ask them what the word "fermentation" brings to mind. As with almost every question that I ask my students, answers vary wildly. For some students, it brings to mind gross rotting things that smell bad; for others, they picture wine, beer, or other alcoholic beverages; and, for a surprisingly large number of students, it makes them think of the game Minecraft (apparently there is an in-game item called fermented spider eyes). In reality, fermentation is a beautifully-designed process that is used in many different products both in the ancient world and in modern society.
At its heart, fermentation is a chemical process that is performed by many living things (including humans!). So, to understand it, you need to know a little bit about living things and a little bit about chemistry. Fear not, though! I am here to lead you through the science of this fascinating process.
Read on as we explore the science of fermentation.
A Little Bit about Living Things...
The first basic thing you need to know about living things is that all living things require energy in order to do just about anything. However, not every type of life goes about acquiring this energy in the same way. In general, there are three different ways organisms have been designed to get this energy.
So, the main idea here is that fermentation exists as a means for many forms of life to obtain energy from some food source. And remember that all living things are just trying to stay alive, and for many things, that involves fermenting things.
A Little Bit about Chemistry...
Ah, chemistry, how many students dislike you and find you uninteresting and/or intimidating? Sadly, far to many. For to understand anything about why anything happens on earth we need to know at least a little bit about you.
It is interesting to note that if you zoom in far enough, all of us and everything around us are all just a bunch of chemicals that are being held together in various shapes (physically-speaking of course). All living things, including us, are largely made up of water contained within bags of carbon. The air around us, though invisible to our eyes, is made up of many chemicals - mostly nitrogen and oxygen gas. The earth, soil, and rocks under our feet are also various sorts of chemicals. How these different chemicals interact with one another is what chemistry is all about.
The most important chemical when talking about energy in food is glucose (a type of sugar). Glucose is the chemical that plants (and other photosynthetic life) store the sun's energy in. Then, at some later time, living things can break up that glucose and take some of the energy out of it. They literally cut the glucose in half (just in case you wanted to know, each half of the glucose is now called pyruvate). When that happens, a little energy is released and is used to charge up the cell's batteries - a molecule called ATP.
This is where it gets a little tricky. Another chemical is needed to break glucose in half. It is called NAD+. Its actual function is to take electrons from glucose which allows it to split. Once it takes those electrons, it is called NADH. It is important to remember that NADH is the same as NAD+ but with some extra electrons - it is akin to just you (NAD+) and you holding a ball (NADH). However, the cell only has a certain number of these NAD+/NADH. So, in order for a cell to continue cutting up glucose and getting energy from it, it needs to regenerate NAD+.
Now this is where fermentation comes in. Fermentation helps NADH become NAD+ again so that more glucose can be cut in half and release energy. As will be covered in a later post, there are two main ways this can be done, so there are two different types of fermentation: alcoholic and lactic acid.
When utilizing fermentation in our foods, we don't really care about the NAD+/NADH directly; what we actually care about is what is made as a byproduct. These fermentation byproducts are: carbon dioxide gas, ethanol (alcohol), and lactic acid.
And we will look at these in the next "Science of:" posts.
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Simple Life Homestead