Amount of Salt to Use for Fermentation

Reader Contribution by Sandor Katz
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I want to start fermenting my harvests. How much salt should I use to make sure my fermented vegetables are safe to eat? And what’s the best container to use for fermentation projects?

Traditionally, vegetables have been fermented with lots of salt. In addition to pulling water from vegetables, salt hardens pectins in vegetables, both rendering them crunchier and discouraging the growth of bacteria other than lactobacilli. By inhibiting competing bacteria, salt enables the vegetables to ferment and keep for longer periods of time. Because preservation has historically been one of the important motivations for fermentation, ferments have tended to be quite salty. But for health-conscious people interested primarily in flavor and nutrition, less salt can be better. Salt lightly, to taste. Adding salt is easier than taking it away, but if you oversalt, you can dilute by adding water or more vegetables. As a starting point, try 3 tablespoons of salt per 5 pounds of vegetables. More salt will slow the fermentation process; less (or none) will speed it up. Ferments with less salt may be more prone to surface molds. You can leave out the salt or use various mineral-rich substitutes, such as celery juice (my favorite salt-free variation) or seaweed. Just be sure the vegetables are submerged in the liquid.

Some people promote the idea that salt-free sauerkrauts contain more beneficial organisms than salted krauts. I don’t believe that. The most specific beneficial bacteria we’re after, lactobacilli, are salt-tolerant and abundantly present even in salty krauts. Arguably, salt-free ferments are more biodiverse, but this diversity often results in mushy textures. Though fermenting vegetables without salt is possible, a little salt results in far superior flavor and texture — and just as much beneficial bacteria.

Heavy ceramic cylindrical crocks are the ideal fermentation vessels, though they can be expensive and hard to find. Glass containers work well, especially those with a cylindrical shape or a wide mouth. Crockpots with ceramic interiors make effective fermentation vessels, and you can often find them in thrift stores. In a pinch, you can use plastic, but even food-grade plastics leach toxic chemicals.

The reason a cylindrical shape is desirable is for ease of weighting down the fermenting vegetables to keep them submerged rather than floating to the top. I generally use a plate that just fits inside the vessel, weighed down by a full jug of water, and I drape a cloth over the top of the vessel to keep flies out. I call this the “open-crock” method. Containers in other shapes can work with improvisation, or you can manually press the vegetables to submerge them in the liquid.

Whatever type of vessel you use, pack the vegetables into it with some force (unless they’re whole) to break down cell walls and release juices. I use a blunt wooden tamping tool. You can improvise with a piece of wood or your fist, or you can manually massage and squeeze the vegetables. After the vegetables are weighted down, the salt will continue to pull moisture from the vegetables for many hours. If, by the following day, the vegetables aren’t submerged, add a little water.

“Ferment until ripe,” many recipes advise, but ultimately you’ll have to decide when your fermented vegetables are ripe. Sour flavor — from lactic acid — develops over time. Longer fermentation translates to tangier flavor. This happens more quickly in warm temperatures than in cool ones. If you start your ferment at harvest time, in autumn, as temperatures are dropping, it can ferment for six months or longer. This is one way people survived before refrigeration. Many people, however, prefer the flavor of a mild ferment to that of a strongly acidic one. When you’re first experimenting, taste your ferments early and often. Serve some after three days, then three days later, and again three days after that. Familiarize yourself with the spectrum of flavors that fermentation can create and see what you like.

Adapted from The Revolution Will Not Be Microwaved; printed with permission from Chelsea Green Publishing.