Five Vegetable Fermentation Mistakes You Are Making

by Kaitlynn Fenley

It’s so easy to get fermentation right! But there is a lot of fermentation misinformation on the internet. So let’s go over the five main vegetable fermentation mistakes you might be making. If you avoid these mistakes, you’ll have safe, probiotic delicious ferments every time.

Most of us have heard by now that properly fermented vegetables are the best source of natural probiotics for gut health.

But how do you make fermented vegetables properly? Can we ensure our fermented foods only contain good bacteria? How do you know the recipe author developed the fermentation recipe you’re using with basic food safety in mind? How do you optimize fermentation for ideal health benefits?

These are such important questions, especially if you want what is best for your gut microbiome health! 

It’s so easy to get fermentation right… But there is a lot of fermentation misinformation on the internet.

There’s pretty much two ways to “get fermentation right”. The first is cultural and traditional time-tested recipes.

If you want to make traditional fermentation recipes from other cultures, find a teacher from that culture who provides these recipes (there are so many) and follow EVERY step, method, temperature, time, and ingredient. Cultural and traditional recipes are time-tested and made in specific ways for a reason.

The second is original new recipes developed with food science, microbiology, and consistency in mind. Recipes that use exact measurements, mass units, and optimal methods so everyone around the world who makes the recipe has good results. 

So let’s go over the five main vegetable fermentation mistakes you might be making. If you avoid these mistakes, you’ll have safe, probiotic delicious ferments every time.

using my hands to place a fermentation weight into the jar of sauerkraut.

Here are the five most common vegetable fermentation mistakes

These mistakes can lead to bad flavors, inconsistent results, and unsafe fermentation projects.

  1. Not weighing your ingredients
  2. Using the wrong salt concentration
  3. Not keeping everything submerged
  4. Not fermenting for a long enough time
  5. Adding unnecessary ingredients 

How to avoid the most common vegetable fermentation mistakes:

Weigh Your Ingredients

Do you have trouble achieving consistency across batches of fermented vegetables? It’s probably because you aren’t measuring your ingredients properly. For fermentation, all ingredients need to be measured in mass units, like grams.

When we talk about fermenting vegetables, we specifically refer to a microbial process called lactic acid fermentation. This particular fermentation occurs when certain bacteria produce lactic acid by fermenting plant compounds for energy. All it takes is the addition of a precise salt concentration to vegetables, and you can turn plain old produce into flavor-rich superfoods. The only way we can achieve an exact salt concentration is to measure ingredients in mass units.

You can read all about using weight measurements in fermentation recipes here.

Use the Correct Salt Concentration

Not using the proper salt concentration is a major cause of concern. Salt concentration controls microbial growth before lactic acid bacteria can produce acid to preserve the vegetables. Basically, salt roots for Leuconostoc bacteria to start thriving while discouraging yeasts from thriving. This leads to a quick and safe drop in pH. 

A SPECIFIC salt concentration is VITAL and extremely effective in controlling dangerous fungi, gram-negative bacteria, and the toxins they can produce in the first few days of fermentation. This is because specific salt concentrations encourage the growth of desirable, beneficial microorganisms that rapidly and steadily decrease the pH and preserve the vegetables. These bacteria include Leuconostoc spp. and Lactobacillus spp

If you’re looking for guidance on calculating and measuring salt concentrations you can reference The Complete Guide to Safely Using Salt in Vegetable Fermentation.

Keep Everything Submerged

Certain microbes love oxygen, certain microbes love anaerobic environments. Oxygen levels directly influence which microbes thrive. Everything has to stay submerged in the liquid while fermenting.

Fungi will find a way to grow if all ingredients are not submerged in the liquid during fermentation. Fungi do undesirable things in vegetable fermentation. Some fungi produce toxins, and some can metabolize acids, increasing the pH and negating the preservation effects of lactic acid fermentation. 

You can learn more about keeping fermented vegetables anaerobic here: How to Keep Fermented Foods Anaerobic

Allow For a Long Enough Fermentation Time

Too short of a fermentation time robs you of so many beneficial postbiotic compounds. When given enough time, Lactobacillus spp. produce bioactive peptides and polyphenols that are wonderful for health. Lactobacillus only start to thrive, metabolize, and produce their byproducts AFTER about 7-14 days of fermentation (this timeline can change with temperature, unique methods, and additional ingredients like that of cultural and traditional fermentation recipes). So, being patient with fermentation projects is the way to go. Anything after seven days is probably okay to taste test, but I like my ferments right around 21-28 days for maximum health benefits. If a moderate temperature is maintained (60-85° F), I suggest refrigerating at 28 days for optimal sensory qualities and health benefits. Hotter temperatures can encourage fermentation to proceed much faster, so if fermenting is above 85° F, you may find your fermented vegetables done at 12-14 days.

Fermenting vegetables for a proper amount of time also influences biogenic amine (histamine) content. If Lactobacillus spp. are given enough time to thrive and then metabolize, a lot of these species have the ability to degrade and decrease biogenic amines in all types of fermented foods. You can read more about the vegetable fermentation timeline here.

Keep It Vegan If You Have Gut Issues

Just like eating many different vegetables influences the composition of your microbiome, fermenting different foods with different ingredients changes the structure of the microbial fermentation community. Vegetables & fruits with ample sugars encourage yeasts to thrive, leading to excess alcohol production and possible acid metabolism by yeats. This metabolism can negate the preservative effects of fermentation.

Including animal products in fermentation, like whey and fish paste, can lead to microbial-produced biogenic amines. This can cause histamine reactions for some people when consumed.  I stick to vegan fermented vegetables only, and if I use fruit in fermented vegetables the fruit does not make up more than 1/4 of the ingredients. You can read more about biogenic amines in fermented foods here.

A note on traditional and cultural fermentation recipes

Some traditional fermented foods, like baechu Korean kimchi and Dưa Chua Vietnamese fermented vegetables have a swift fermentation time. This is thanks to specific ingredients and traditional methods.

Dưa Chua for instance is made by drying vegetables in the sun then submerging them in a brine that includes salt and sugar. Dưa Chua is usually fermented for about 4 days at 80-95° F.

Baechu Korean kimchi is made by soaking nappa cabbage in a high salinity brine for 12 hours before it is rinsed and rubbed with a paste made of salted shrimp, fish paste, gochugaru, sugar, ginger, garlic, and scallions. Then it is packed into a fermentation crock and enjoyed after only three to seven days of fermentation.

In both of these examples, the ingredients, methods, and temperature are very important factors in the fermentation time and quality of the finished product. If you want to make traditional fermentation recipes from other cultures, find a teacher from that culture who provides recipes (there are so many) and follow EVERY step, method, temperature, time, and ingredient. It is only right to respect the complexity of carefully developed traditional techniques.

Are You Interested In Making Fermented Foods At Home?

Try out these recipes:

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Leave a Comment


Huda January 26, 2021 - 2:46 pm

Hello..I made from fermented vegetable juice as a salad dressing, after fermentation I added a little raw apple cider vinegar and olive oil to it, but the mixture separated and did not mix
Is there a way to make it more homogeneous?
And what is the correct way to ferment lemon?

Kaitlynn Fenley January 26, 2021 - 5:24 pm

Salad dressings made like that will never fully mix… Since oil and water separate. You can put it in a bottle and shake it before using it.

I’ll see if I can put a salted preserved lemon recipe on our blog!

Daniel August 5, 2021 - 7:36 pm

Your blog is amazing!

I read an article* about pesticide residue in vegetables. It said that the fermentation processes leads to a reduction in pesticides levels and formation of new pesticides by-products. And the presence of pesticides may decrease the growth rate of fermentative microbiota. Also said that by washing the vegetables also reduce the levels of pesticides.

I live in Buenos Aires and it is sometimes difficult to purchase organic vegetables, is it possible to make a good fermentation with non organic foods by using some washing method ?



Kaitlynn Fenley August 11, 2021 - 3:07 pm

It is possible to make fermented foods with conventional produce and have good results. But pesticide and fungicide residues can harm the vegetable microbiome making fermentation difficult. Washing methods will not remedy this problem, because the problem is missing microbes. The best route to take is to ferment vegetables on the “clean 15” EWG list, like cabbage, and stay away from conventionally grown vegetables on the EWG dirty dozen list. If there is a farmers market or and small farm that locally grows produce you can buy from, these are good options even if its not “certified organic”

Jay July 23, 2022 - 10:31 am

we grow a good many collards in our organic garden and I was wondering about fermenting them. Have you had any experience with Collards ? Also squash’s, zucchini, etc. Thanks!!!

Kaitlynn Fenley July 24, 2022 - 2:24 pm

I’ve mixed collards in with cabbage to make sauerkraut and it was really good!