What Is Alcoholic Fermentation? The Science Behind It

What Is Alcoholic Fermentation? The Science Behind It

Ever wondered how your favorite alcohol is made or how our ancestors made their favorite hard beverages before modern science? Both of those questions have a simple answer: fermentation.

If you’re looking for a more in-depth answer, we have that, too. Like yeast breaking down sugar, we’re breaking down the science behind fermentation and how this process became a staple in the beverage industry.

The Science Behind the Sips

Fermentation is a process that chemically changes animal or plant matter. The change occurs thanks to yeasts, bacteria, and molds that use the organic material as fuel. These organisms break down the organic material into smaller, simpler compounds, like gasses, acids, and of course, alcohol.

When it comes to fermenting your favorite hard beverages, most brewers use yeasts to feast on plant sugars (like glucose and fructose, creating the alcohol we’re familiar with. Also called ethanol or ethyl alcohol, this alcohol left behind from yeasts can dissolve in water, making it a popular ingredient for other types of products, including cosmetics and gasoline.

The Different Types of Fermentation

There are several different types of fermentation. There’s lactic acid fermentation, which is used to make foods like pickles, kimchi, and sauerkraut. There’s also acetic acid fermentation, which is used for various kinds of vinegar. However, the ethanol or alcohol fermentation process is the one we’re concerned with.

The Science Behind Alcoholic Fermentation

Science class alert! This is your warning to skip ahead if you don’t want to get into all the scientific mumbo-jumbo behind fermentation.

That alcohol fermentation process begins with hungry yeast cells feasting on sugar and breaking it down into pyruvate molecules. (The scientific name for that step is glycolysis.)

As the yeast breaks down the sugars, the glucose molecules turn into pyruvic acid molecules. (For the scientists in the room, those sugars also produce ATP, NADH, and NAD, a.k.a molecules that are crucial to human metabolism.) Those new pyruvic acid molecules then break down one more time into carbon dioxide and the ethanol that gives hard drinks their buzz.

Humans might need oxygen to breathe, but when it comes to making your favorite hard beverages, oxygen is not a part of the equation. Fermentation is an anaerobic process, meaning that it happens in the absence of oxygen. Add oxygen to the mix, and you won’t end up with that perfect brew you were hoping for. For that reason, anaerobic conditions are crucial to fermentation.

At the end of the day, although the ethanol fermentation process might sound super complex, it is simply a chemical reaction that transforms sugar into alcohol and carbon dioxide without the presence of oxygen. This reaction results in the tasty byproducts that the modern world knows and loves.


For lower alcohol by volume drinks, the yeast fermentation alone is enough to get the right amount of buzz. For drinks with a higher ABV, brewers need to use another ethanol production process called distillation.

Why is that? Well, we already know how much yeasts love sugar and carbohydrates, but if they eat too much and create too much alcohol in the process, the chemical reaction will actually kill the yeasts. ABV can reach between 5% and 21% before the yeasts rest in peace.

Distillation is the process where different parts of a brew are separated. When creating spirits, the alcohol content is extracted from the rest of the brew, leaving only the hard stuff.

This is done by boiling a mixture of alcohol and water. Since water has a much higher boiling point than alcohol, the alcohol is boiled first, transforming it into a gas. Once separated from water, the temperature is lowered, bringing it back to a liquid for an end product of almost pure alcohol.

Fermentation Through the Ages

Even before humans started intentionally making fermented products, there’s evidence that our early primate ancestors ate naturally fermented fruit that had fallen to the ground. Yeasts, bacteria, and molds would work their magic on the natural sugars in fruit and convert them into alcohol, likely causing the first buzz in history. This early exposure in our evolutionary line helped humans eventually develop the gene that lets us process alcohol. Now that’s an evolution revolution.

Fermentation for the Ancients

Alcoholic fermentation is nothing new; in fact, the earliest known instance of humans purposefully fermenting a beverage was in 7000 BCE. Thanks to residue left in ancient Chinese clay pots, archeologists identified a brew of fermented rice, honey, millet, and grapes as the first recorded alcoholic beverage. It’s possible that fermented drinks were brewed even before that, just without recorded evidence.

Fermentation quickly spread across the globe, with each culture brewing its own unique beverages with the native plants that grew in its climate. For example, Egyptians and Mesopotamians made beer from the local grains that grew in the region. Greeks and Romans took advantage of the grape-friendly climate they lived in and used grapes to create a famous wine-making culture. In the region that is present-day Japan, locals used rice crops to brew sake.

Because ancient cultures were limited to the native plants that grew in their home regions, drinks using non-native ingredients became a luxurious rarity. Trading these goods was difficult, as they would spoil quickly, sometimes too quickly to be delivered on a trade route.

For trading purposes, spirits became the more popular option. Distilled spirits resulted in a much stronger drink that didn’t spoil as quickly. Because alcohol killed harmful microbes and microorganisms, it was also used as an effective way to keep water fresh for sailors and merchants during long trade excursions. Enter the era of rum-loving pirates.

Modern Fermentation

As technology developed, humans found more efficient ways to brew their favorite beverages, eventually leading to the innovations we use today. Breweries and distilleries can make bigger and faster batches and transport them more efficiently than before, so you can find brews from all over the world at your local store — just without the pirates.

If you’ve fallen in love with fermentation, you can actually make a career in studying it. Alcoholic fermentation is such a large industry that there’s even a name for the scientific study of fermentation: zymology.

Zymologists study the ways fermentation can be used for medicinal purposes and the best ways to produce fermented foods and beverages. They also dive deep into the biochemical reactions and ingredients that make up the process — from the best kind of brewer’s yeast (saccharomyces cerevisiae) to the best enzymes (a.k.a. alcohol dehydrogenases) — to result in the best end product. Of course, if you’re like most of us, you’ll probably just stick to sipping and leave the science to the professionals.

Hard beverages have come a long way since their earliest days. Ancient brewers would probably be proud of how far fermented drinks have come — and extremely jealous that they didn’t get to try all the new drinks we’ve invented. Today, we have countless creative hard drinks, such as hard seltzers, lemonades, and our favorite, hard kombucha.

Hard Kombucha — Fermented to a Tea

Kombucha, whether regular or hard, uses fermentation to transform tea, sugar, and yeast into its tangy form. To make it the 21+ variety, it’s fermented for longer to allow the ABV to develop.

At Flying Embers, we take the ancient process of fermentation and enhance it with modern science. The process starts with our USDA-certified organic ingredients that make up the base of each brew. We take pride in verifying our ingredients as organic to ensure you’re getting a drink that fits perfectly with your lifestyle.

We start with organic black tea steeped with an adaptogen blend of ginger, turmeric, and ginseng. Next in the mix is our organic cane sugar that our champagne yeasts love to feast on. We prefer to use cane sugar over another popular sugar source, honey, for a vegan-friendly brew.

Every brew starts with our base ingredients, and then we add plant botanicals and superfruits to produce our unique flavors like Grapefruit Thyme and Mango Coconut. We don’t use any sugar to flavor our drinks, making our final product sugar-free. All the organic sugarcane is eaten up by the yeast strains, leaving none in our drinks when fermentation is over.

On top of being organic and sugarless, we keep our ingredients vegan, gluten-free, and keto-friendly, because we care about what we’re drinking, and we know you do as well.

The mixture of ingredients ferments anywhere from 18 to 30 days at 30 degrees celsius. Because we like to be deliciously boozy , our booch undergoes two rounds of fermentation. The first round is anaerobic, and this is the stage where our yeasts work their magic and transform sugars into alcohol. The second round is aerobic, where our booch produces those signature acids that give it that classic tangy taste.

Without the work of our ancestors, fermentation specialists, and yeasts, we wouldn’t have the fermented beverages we know and love today. The next time you enjoy beer, wine, or our hard kombucha, why not raise a toast to fermentation?


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Ethanol Uses, Benefits, and Chemical Safety Facts | Chemical Safety Facts

Alcoholic Fermentation - An Overview | ScienceDirect Topics

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What Is Distillation? Principles and Uses | ThoughtCo

Fermentation - an overview | ScienceDirect Topics

Ability to Consume Alcohol May Have Shaped Primate Evolution | Science | AAAS

Rod Phillips: A Brief History of Alcohol | TED Talk