I have recently been browsing a wonderful book called The Art of Fermentation: An In-Depth Exploration of Essential Concepts and Processes From Around the World, by Sandor Ellix Katz. It is a beautifully written book, and Katz’s expertise and passion for the subject are easy to see. One of the things I like about it is the relaxed, exploratory attitude he has towards the subject– for example there are no exact recipes, but rather general descriptions of the processes, with lots of detailed explanations and many possible variations. It is the “art” of fermentation, not the science, and it reflects the amazing variety of fermented foods around the world.
What is fermentation? Katz describes it as “The transformation of food by various bacteria, fungi, and the enzymes they produce.” Some of the most recognizable ones in the US are alchohol, vinegar, pickles, sauerkraut, kimchi, yogurt, certain cheeses, and salami. One of the primary functions of fermentation is to preserve foods, and another is to increase health benefits.
Fermented foods have been highly valued in traditional cuisines throughout history and in every culture. Fermented foods that still have live bacteria are known as probiotics, and they are very important for our digestive health, immune function, and more. The importance of our microbiomes (the friendly bacteria that live on and in us) is a huge area of research right now, and we are only beginning to understand how very important they are. One amazing fact is that the bacteria cells living in our body outnumber our own cells about 10 to 1. (The bacterial cells are much smaller.)
The health benefits don’t only come from probiotic content, however. The fermentation of foods is essentially their “pre-digestion” by bacteria and fungi. As Katz explains, this breaks down compounds to make them easier for us to digest, and makes minerals and nutrients more available to our bodies. Fermentation can also break down substances that would otherwise be toxic. It can also actually increase the nutrients in foods; for example, it can increase levels of B vitamins and create helpful enzymes and other compounds.
Katz’s book is an incredible resource, with wide-ranging information from around the world, and instructions for making fermented foods from wine to grain porridges to cheeses to pickled fish… and that’s only scratching the surface.
In finding a place to start fermenting, sauerkraut is a familiar food that is also very straightforward to make. The basic steps are to chop, salt, squeeze out the water, then pack the cabbage into a container so that it is submerged under its juices. The final step is to let sit for some length of time– it can be as little as three days, or it can be a month or longer, depending on preference. Here are some more specific instructions:
Start by pulling an outer leaf or two off the cabbage and setting it aside. You can use the leaf as a “lid” to help hold everything in place as it ferments (though it is optional).
Next, chop the cabbage. As Katz expains, it doesn’t really matter what size the pieces are, but the smaller the pieces are, the more surface area there is, and the easier it will be to squeeze the water out of the leaves.
The next step is to lightly salt the cabbage. Katz suggests salting to taste, though other recipes suggest specific amounts such as 1-2 tablespoons of coarse salt for a large cabbage.
After salting, the cabbage needs to be squeezed and pressed until water is released. You can simply use your hands to squish and bruise the leaves until they are wilted and water pools at the bottom. It took less than 10 minutes for me to squeeze this batch. If you have a large cabbage you might want to do it in smaller batches.
Now it’s time to add seasonings! For a classic version, you can simply add around a tablespoon of caraway seeds. Pepper can be added to taste. Try a couple of cloves of chopped garlic, or add diced jalapeno for a spicier version. The possibilities are endless… I split this batch into two and decided to try grated turmeric in one, and simply ground pepper in the other.
As Katz explains, spices act as mold inhibitors, so they are functional as well as delicious– they help keep mold from growing on the surface. They are also functional for our health; for example, turmeric has medicinal properties such as being antiviral and an antioxidant. The turmeric does add a slightly bitter taste.
Once the kraut is seasoned, it’s time to place it in a container such as a jar. (Don’t use a plastic container.) Press the cabbage firmly into the jar so that it is fully submerged. Fermentation is an anaerobic process, meaning that it it happens without the presence of oxygen. This is why it needs to be under water.
Here is where you can wedge the reserved cabbage leaf on top. If things are still sticking out of the liquid you can top it off with a little extra water. It helps to put some sort of weight on top, like a shot glass, to help hold everything under the water. Only fill the jar up to 3/4 full, because it will bubble and expand as it ferments.
Finally, I place the lid on the jar, but don’t seal it, so that gases can escape. I put a paper bag over the jars to protect them from light, and try to keep them at a reasonable room temperature. You can taste the sauerkraut periodically, starting at around one week. I typically do two weeks, but a you can also do a month or more. The salt level and the temperature also affect the fermentation rate, so in the summer it will ferment more quickly. Once you’re satisfied with it, it will keep in the fridge… potentially for years… but hopefully you’ll eat it sooner!