Fermenting Basics

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What Is Fermenting?

Fermentation is the process of converting carbohydrates to alcohol or organic acids using microorganisms such as yeast or bacteria—usually under anaerobic conditions.

Fermenting is a natural occurrence, meaning that it can and does happen without humans doing anything. Sometimes grapes or berries will drop off the vine and ferment naturally on the ground. Then animals, usually birds, will eat the berries and stagger around, undoubtedly “feeling no pain”.

Since humans have been fermenting for thousands of years there are a few different definitions of fermentation, all of which are accepted as either scientific or traditional. But for our purposes here let’s stick to the definition I just gave you a few paragraphs up. With that definition in mind, I submit to you four different kinds of ferments.

Some people will argue that there are only two kinds with the third being a derivative of the second and that the fourth is not really a “kind” of ferment. And they would not be technically wrong. However dividing fermentation into these four categories will help you understand what’s going on with your ferment, and then more importantly how to troubleshoot.

4 Different Kinds of Ferments

  1. Lactic Acid Fermentation–(Lacto-Fermentation for short) is when bacteria called Lactobacillus produce lactic acid around and inside the food being fermented. This lowers the pH and creates an acidic environment where harmful bacteria cannot live. Yogurt and Sauerkraut are produced this way. This type of ferment also produces probiotics.
  2. Yeast Fermentations– Yeast converts glucose to ethyl alcohol and carbon dioxide (CO2). Wine and beer are made this way along with any other kind of alcoholic brewing. Then also bread made with commercial yeast is created this way (we’ll talk about sourdough in a minute).
  3. Acetic Fermentation–Happens after a yeast ferment. Bacteria in the air take the alcohol and turn it into vinegar. You’ve heard of wine turning to vinegar? This is what happens when wine is exposed to air for too long (or cider, or anything else with alcohol). Sometimes it’s intentional and sometimes it’s not.
  4. Mixed Ferments–Ferments that have both a yeast and a bacteria ferment going on at the same time. They usually require a S.C.O.B.Y. (symbiotic colony of bacteria and yeast) or starter. Kombucha, sourdough, kefir are all examples of this type of ferment.

What about mold?

Some people think using mold in cheese is a fifth ferment, but the mold is doing other things to the cheese–it’s not converting carbohydrates to alcohol or organic acids. So it’s not really a ferment. Some foods do have a combination of mold growth and another type of fermentation. Clearly, you can see how all this could get murky.

Benefits Of Fermenting

  • Produce Alcohol–There are a lot of reasons producing alcohol is beneficial from religious ceremonies to medical reasons (think tincture) to party reasons. I won’t go into a lot of details here. However, I want to point out that throughout history people have made wine to drink when water wasn’t so safe. I’m not suggesting you ever replace water with alcohol, but I think it’s important to understand how the fermenting process makes a safer drink if conditions are bad.
  • Preserve Food–Food will last longer because in the case of lacto-fermentation the good bacteria crowd out the bad bacteria and create an environment where the bad bacteria can’t survive. In the case of yeast fermentation alcohol preserves grapes and helps preserve herbal remedies.
  • Health Benefits–Fermenting foods make food more digestible. Since the food is pre-digested it makes nutrients more bio-available. Also, live cultures help many parts of bodies. You’ve probably heard about the benefits of probiotics. In addition, anti-nutrients are removed through fermentation – these are things that interfere with our bodies absorbing the nutrients in our food.
  • Save Fuel–Often fermented foods can be cooked faster or don’t need to be cooked at all. Also, refrigeration is not necessary. Even though it can be used as a tool to slow the fermentation down, it’s not necessary. There is a great energy saving aspect of fermenting.
  • Makes Food Less Toxic–For example, raw olives are bitter tasting and slightly toxic. Then some nuts have to be soaked before they can be harvested.
  • Taste–Fermenting food gives foods a new dimension of taste. You can easily taste this in cheese, meat, chocolate and yes, fermented coffee.


Fermented food does not last forever because it has organisms that are alive. How long they last depends on the type of food, the pH and the environment in which the food is kept.

Each culture has developed its own fermented traditions, so what might taste good to someone, who has grown up on a certain kind of fermented food, might not ever taste good to you. For example, in the arctic they bury fish so that it will ferment. If you’re from the tropics and go to the arctic that fermented food might not taste good to you. And furthermore, you might not be able to tolerate it. It might be nauseating to you and even if you get past the smell you might not have the acquired the correct microbial ecology to tolerate it. So it could make you sick.

Of course, using common sense is helpful, if it smells bad it probably is, but don’t get strong smell and rotten smells mixed up. Signs of mold, massive discoloration and other obvious signs of spoilage need to taken seriously.

How To Get Started?

You can go with easy or something that motivates you.


If you want easy try making some sauerkraut. Cabbage is one of the easiest things to ferment.

Go With Something That Motivates You

Pick something that you really love and learn how to ferment it. Do you love yogurt? Learn to make that. Do you love kombucha? Learn to brew that! Do you love making your own spirits? Then start there. We have an entire homebrewing eCourse where we teach you how to make cider, beer, wine and more.


Minimum Required: Jar (Mason jar), weight, recipe, and ingredients.

Minimum Required: fermentation jug, airlock, tube to siphon, recipe and ingredients.

Cheese Making (soft cheese)
Minimum Required: a few pots, some cheesecloth, recipe, and ingredients.

From Natural Yeast
Minimum Required: flour, water, yeast, and salt

From Commercial Yeast
Minimum Required: sourdough starter, flour, water, and salt.

Kombucha–S.C.O.B.Y., tea, sugar, water, and a little leftover kombucha.

Common Questions:

Is that mold?
Maybe? Typically if it’s green and at all fuzzy it’s mold. Mold can be other colors so it’s this is a general rule, not an absolute rule.

Do you have to have an airlock?
It depends on what you’re fermenting. If you’re pickling then–yes, if you’re brewing alcohol homebrewing then–yes, if you’re making kombucha or sourdough then–no

Do you need a starter?
It depends on what you’re brewing. If you’re making kombucha, yogurt and sourdough then–yes. If you’re making sauerkraut or old fashioned pickles then–no

Final Thoughts

Fermenting is making a comeback but has rivaled canning for some time. Canning, Dehydrating and Fermenting all have their place in home preserving.