How much salt to use for the perfect lacto fermentation salt ratio is a common question. Let’s go over how much salt to use when fermenting vegetables, and how to measure the perfect fermenting brine ratio.
The Perfect Lacto Fermentation Salt Ratio
Particular concentrations of salt pave the way for creating a happy home for lactic acid-producing bacteria. Mainly, Leuconostoc and Lactobacillus bacteria thrive in fermented vegetables.
When trying to determine the perfect lacto fermentation salt ratio, it isn’t about how salty or not salty you like your fermented vegetables. We have to focus on how salty certain microbes like it.
All the microbes needed for the fermentation process are already present on your vegetables, even after you wash them. Once you provide the proper salt concentration, bacterial succession can occur, and lactic acid can be adequately produced.
How to Measure the Perfect Fermenting Brine Ratio
To use a precise and accurate salt concentration, you must use units of mass to measure your salt.
There are two mathematical ways to create an exact percent salt concentration, and the desired salt concentration varies by type of vegetable.
You can see recommended salt concentrations in our blog, The Complete Guide to Safely Using Salt in Vegetable Fermentation.
Let’s look at 2.5% as an example
To create an exact 2.5% total salt concentration, place a bowl on a scale and tare/zero the scale. Add 2.5 grams of salt to the bowl, then add your produce and any water into that same bowl up to 100 grams. That’s a 2.5% total salt concentration.
What we do is slightly different and easily applied to variable amounts.
How We Measure the Perfect Fermenting Brine Ratio
We weigh all our produce and water, multiply that weight by 2.5%, and add the number we get in grams of salt.
This results in an approximate 2.5% salt concentration that is perfectly safe and optimal for fermentation. Also, this mathematical method can work with any total salt concentration.
lacto fermentation salt ratio example:
If we have 100 grams of produce and water, we multiply by 2.5%. 100 x 0.025 = 2.5. So we add 2.5 grams of salt. This ends up being a 2.44% total salt concentration.
To calculate the total percent salt concentration of the entire mixture, you divide the grams of salt by the total grams of the whole mixture: 2.5 grams of salt / 102.5 grams (of salt + water + produce) = 0.02439.
Move the decimal to make it a percent, and you get 2.44%
And guess what? With this method, we end up with 2.44% salt, no matter the weight of vegetables or water… if we add 2.5% salt, the resulting total salt concentration will always be 2.44%
lacto fermentation salt ratio example 2:
If we have 756 grams of cabbage and water, we multiply that by 2.5%. That equals 18.9. So we add 18.9 grams of salt.
18.9 / (756+18.9) = 0.02439
Yep. That’s 2.44%
You will only get a consistent salt concentration throughout different fermentation batches by weighing the produce and water, doing math, and then weighing out your salt.
Lacto Fermentation Salt Ratio
You might be wondering why we use the weight of water and the weight of vegetables to determine the perfect salt ratio for fermentation. All vegetables are at least 93-98% water, so you must account for the water inside the vegetables. Because of osmosis and concentration gradients, the total salt concentration includes the water in the vegetables.
Between batches and throughout the seasons, the weight of the vegetables you are fermenting will vary, because the water density of the vegetables will vary. For instance, a summer cabbage is much lighter than a winter cabbage because summer cabbages aren’t as water-dense.
Measuring Salt in Vegetable Fermentation
You may also be wondering why we should use weight to measure ingredients. Simply put, the same volume of different salts, contains different amounts of NaCl.
Depending on what brand, style, and type of salt you are using, the amount of NaCl in a volume measurement, such as a tablespoon, varies greatly.
Unrefined sea salt can be found in many different “grains,” such as flake, large grain, small grain, etc. A teaspoon of flake salt has a mass of about 1 gram. A teaspoon of small-grain Himalayan salt has a mass of about 3 grams.
If you add a teaspoon of flake salt to 100 grams of vegetables and water, you get a 0.99% salt concentration. If you add a teaspoon of Himalayan salt to 100 grams of vegetables and water, you get a 2.9% salt concentration. That’s a huge difference, and the 0.99% salt concentration is completely unsafe and probably won’t select for probiotic microbes.
Other Fermentation Factors
Accurate salt concentration, adequate time for the fermentation, and proper temperature are necessary for a healthy population of microbes to develop in vegetable fermentation.
The temperature for vegetable fermentation should be between 70-80 degrees F. However, anywhere between 60 and 90° F is acceptable. The cooler the temp, the slower the fermentation. The hotter the temp, the faster.
Once the temperature is established, the two main factors that need to be tailored to the microbes are salt concentration and length of time for the fermentation.
Suppose all of these things are accounted for appropriately. In that case, the pH of the fermentation will drop, lactic acid will build up, the microbial population will consist only of probiotic bacteria, and the vegetable matter will be preserved.
Get Started Fermenting At Home
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Frias, Juana & Martinez-Villaluenga, Cristina & Peñas, Elena. (2016). Fermented Foods in Health and Disease Prevention.