What’s the process, why does happen, and what’s the difference between it happening “naturally” vs in a fermenter?
In: Biology
Fermentation is the breakdown of sugars into carbon dioxide and alcohol.
What happens in our bodies is a type of this breakdown. But we do it using oxygen.
Microbial fermentation used for alcohol production is done in a oxygen free environment.
This is how they produce energy.
Same process occurs in both. It’s just that artificial is made cleaner so that they can extract alcohol better.
To get energy out of sugar, we use oxygen.
Sugar + Oxygen –> Carbon Dioxide + Water + A lot of energy
However, some microbes can break down sugar partway even without oxygen. This releases less energy because you can’t form the very strong bonds with oxygen, so it leaves something organic (carbon containing molecules) behind.
The two main pathways we use in food are alcoholic fermentation which is done by fungi called yeast and obviously results in alcoholic drinks, and lactic acid fermentation which is the result of bacteria and produces things like yogurt, saurkraut, kimchi, traditional pickles, etc. (your muscles will also use lactic acid fermentation as a last resort if they start running low on oxygen).
Sugar —> Alcohol + Carbon Dioxide + A little bit of energy
OR
Sugar —> Lactic Acid + Carbon Dioxide + A little bit of energy
However, there are tons of different fermentation pathways that different microbes use, depending on the kind of environment they live in. For instance, yeast produce alcohol as a waste product, they can’t get any more energy out of it. But other microbes can, acetobacter can take the alcohol produced by the yeast, and turn it into acetic acid, the main ingredient in vinegar, and this is the traditional way of making it. Interestingly, this process might not be considered fermentation because it uses oxygen.
Alcohol + Oxygen —> Acetic Acid (vinegar) + Water + A little bit of energy
Other microbes can even break that down to single-carbon molecules like methane (CH4), or hydrogen gas.
“Natural” fermentation just involves leaving something out and letting whatever kind of ambient microbes move in and eat it. Specific fermenters are usually inoculated with a specific target microbe that is known to perform the right kind of fermentation, and produce good tasting results if its being used in food. This may involve sterilizng the product to keep other microbes out, maintaining ideal temperature, PH, etc. for the best growth of the target microbe, and carefully choosing which strain to use.
Microbes eat sugar and poop alcohol. “Naturally” is just normal microbes find sugar.
“Fermenter” we select the microbes and add the sugar.
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