Beer & Wine Wine

What Is Alcoholic Fermentation?

In a nutshell, it’s how grapes and grains become booze.

Fermenting grains to become beer
Fermenting grains to become beer. Image:

Getty Images / Urbancow

Whether wine, beer or spirits are more your jam, these boozy beverages have one thing in common: All of them contain alcohol, which means that they all have undergone the process of fermentation. Fermentation is a pretty commonly used term in the alcohol industry, and although the overarching concept is relatively simple to grasp, many imbibers aren’t fully aware of the intricacies of this essential booze-creating process. 

Alcoholic fermentation, also referred to as ethanol fermentation, is a biological process by which sugar is converted into alcohol and carbon dioxide. Yeasts are responsible for this process, and oxygen is not necessary, which means that alcoholic fermentation is an anaerobic process. Byproducts of the fermentation process include heat, carbon dioxide, water and alcohol. In this case, we’re focusing on the latter.

Humans have been using the process of ethanol fermentation for millennia. The ancient Greeks were known for their mead production, which was produced by fermenting honey and water. In the meantime, though, honey has taken a back seat to other foodstuffs, most commonly grains (for beer and spirits) and grapes (for wine). Additional base products include other fruits, such as berries, apples and so on, rice (for sake) and beyond. 

Fermenting grapes to make wine
Fermenting grapes to make wine.

Getty Images / Michael Major

The Difference Between Native Yeasts and Cultivated Yeasts

This is a hot topic among booze creators, particularly within the natural wine community. Native yeasts (also known as wild yeasts or ambient yeasts) are naturally present on fruit skins and in cellars. When a booze producer chooses to let their juice ferment with native yeasts, this means that they’re simply relying on the naturally occurring yeasts found on the raw materials and in the cellar where the fermentation is taking place. When fermentation is done naturally, it tends to take much longer, which isn’t necessarily a bad thing.

When a producer chooses to use cultivated yeasts, this means that a specific strain of yeast is sought out, purchased and added to the raw materials to kick-start fermentation. Yeasts (as with seasonings) come in all different flavors and makeups. Purists will argue that using cultivated yeasts takes away from the authenticity of a raw material, though the fermentation process will generally take much less time and the result is often more predictable and consistent. For these reasons, this is usually the route taken by those producing alcohol in large quantities. 

The Difference Between Fermentation and Distillation

Alcoholic fermentation is the process of using yeasts to convert sugars into alcohol. Distillation is a process used to higher-ABV beverages from already-fermented base products. (For example, the distillation of beer wort creates whiskey, while the distillation of wine produces brandy.) All alcoholic beverages undergo fermentation, thought not all fermented beverages are distilled. 

Fermenting grains that will eventually become spirits
Fermenting grains that will eventually become spirits.

Getty Images / mapodile

Other Types of Fermentation

Fermentation refers to any process in which microorganisms (i.e., bacteria and/or yeast) produce a desirable change in a food. In the context of food and drinks, you’ve probably heard of a few other types of fermentation aside from alcoholic and ethanol, including acetic acid fermentation and lacto-fermentation. 

Acetic acid fermentation is the type of fermentation that produces kombucha, kefir and ginger beer. It uses water, fruit and sugar, and generally involves a starter culture such as a SCOBY (symbiotic combination of bacteria and yeast). 

Lacto-fermentation uses lactic-acid-producing bacteria, primarily from the lactobacillus genus, to break down the sugars in food to create lactic acid, carbon dioxide and sometimes alcohol. The process generally involves combining water, salt and sugar (typically in the form of a vegetable or fruit) in an anaerobic environment. It’s how sauerkraut, kimchi and traditional dill pickles are made. In recent years, more adventurous bartenders have begun experimenting with this type of fermentation to produce complexly flavored ingredients (and brine) to use in their cocktails.