Food preservation methods: Fermentation

Note (Dec. 2014): We wrote this years ago, when we were just beginning to dabble in fermentation but knew little about beneficial microbes and benefits of fermented foods. We were a bit nervous about giving bad advice, so advised cooking the kraut just in case…which in retrospect is a more microbe-phobic mindset than we currently subscribe to. For those interested in fermentation, we strongly recommend Sandor Katz’s excellent books, Wild Fermentation and The Art of Fermentation.

We’ve had questions from new CSA members regarding home food preservation techniques and any relevant items that might make good holiday gifts. We’re thrilled that folks are thinking ahead to preserving next year’s bounty, as that’s the key to getting the most out of a CSA and building the economic sustainability of local foods in general. This series will present some of our experiences and advice, along with ideas for kitchen items that we’ve found to be useful investments as serious practitioners of home food preservation.

Fermentation is a historic food preservation method that has increasingly fallen out of favor since the advent of freezing and canning, but one that remains useful for some vegetables in particular. Cabbage, for example, can be fermented into sauerkraut, a perfectly normal food that nonetheless is almost entirely purchased instead of homemade. Even our hard-core traditionalist German cookbook assumes the home cook buys, instead of makes, sauerkraut. Yet there are distinct benefits to fermenting vegetables yourself.

One useful book on the subject, Keeping Food Fresh (a fascinating collection of traditional Old World recipes and methods for food preservation; the new edition has been renamed Preserving Food Without Freezing or Canning), includes this worthwhile point:

Inevitably, food is altered in the preservation process. However, unlike sterilization (canning) or freezing, many traditional methods do not necessarily mean a loss in flavor or nutritional value. Lactic fermentation, for example, enhances digestion and also increases the enzyme and sometimes the vitamin content, compared with the unfermented food. In other processes, the act of preserving often enhances the flavor of a food rather than its nutritional value.

From another angle, Harold McGee’s eminently scientific tome On Food and Cooking states that:

(the microbes involved in fermentation) leave most of the plant material intact, including its vitamin C (protected from oxidation by the carbon dioxide they generate); they often add significant amounts of B vitamins; and they generate new volatile substances that enrich the food’s aroma.

We’ve found that home-fermented sauerkraut is a tasty and stable way to preserve cabbage (which you can’t really freeze or can), that doesn’t degrade the product, and was well worth our trying over the last few years. We’ve also experimented with fermented pickles and kimchi.

The simplest method, which I drew from Keeping Food Fresh, is to pack shredded cabbage into jars, layered with salt and spices, and let the natural fermentation take hold in a controlled setting. I am intentionally not giving a recipe here, as fermentation (like any other home kitchen experiment) can go wrong if not done right, and folks wanting to try this should rely on a more authoritative source for specifics. But here’s how it looks when I do it:

I shred multiple cabbages using a food processor. For this batch, I did about 20lb of cabbage, 5 ~4lb heads of our excellent fall Napa. I cut out the cores but use the rest, washing it well. For rough reference, this resulted in 4 half-gallon jars packed tightly.

Then I pack the shredded cabbage into quart or half-gallon jars (latter shown here), adding a dose of salt every few inches, along with a few juniper berries per jar. A wooden rolling pin makes an excellent tool for repeatedly mashing down the cabbage into a tightly packed mass, which also helps release some juices. When I’ve packed all I can to the base of the rim, I pour some boiling water into the top, and screw on a good-quality canning lid and ring, a good use for once-used canning lids. You don’t want these to seal entirely, so you don’t water-bath them. The not-quite-seal you get with hand-tightening allows just enough air exchange to allow for controlled fermentation without spoilage. These just sit on the counter or another storage area, and do their thing; weeks or months later, we crack a jar to a loud HISSSS and most of the time a nice, tangy, excellent kraut. We cook it before serving just in case, but usually it’s quite obvious when it’s gone bad (this has rarely happened).
We’ve also tried fermenting cabbages in large open crocks, with less success. For this to work you need to keep all the vegetable submerged in a brine, weighted down, and this has been hard to do with the materials we have on hand. We’ve wasted a distressing amount of cabbage which has just gone moldy. So this fall we ordered a modern German Fermenting Crock (picture below from the linked site) on the strong recommendation of a trusted friend. This new version of the old-school crocks has a special water seal that helps keep the process under control, and seems quite well thought-out. Our trial run is underway, and we’ll report on the results when applicable. We prepared this batch in late November when cabbage was abundant and we were still overwhelmed with other produce. The recommended fermentation time is 4 to 8 weeks, meaning that we’ll have abundant kraut just about the time that our freshly harvested greens take their winter break.
There are many other items, and ways, to ferment. We’ve tried cucumber pickles before, with mixed results. One batch worked okay, but we didn’t prefer the flavor compared to “normal” vinegar pickles, though this may just be what our taste buds are used to. Both we and a good friend have experimented with fermenting kimchi, with very tasty results. The kimchi recipe that we used needed only three days of fermentation at room temperature, yielding very quick results (but arguably not achieving much in the way of food preservation since we ate it in within the time frame the the ingredients could have stored on their own). On the other hand, it was a good way to experiment with fermentation. The quick-fermenting kimchi recipe that we used is from Nourishing Traditions, a cookbook that we saw referenced frequently when we did some online reading on the topic of fermentation; Daniel Boone Regional Library has a copy or two.
Whey is an optional but recommended ingredient for many fermented recipes, because it helps jump start the microbial activity. We use whey from our cultured cheeses such as feta or cheddar (but only if we started by pasteurizing the milk), or we drain yogurt in cheesecloth and collect the whey from that. We don’t use whey from ricotta, because it’s not cultured, and we don’t use whey if it is from an unpasteurized batch of cheese that will be aged (just to be on the safe side).
Books on fermenting are full of interesting and oddball ideas for home cooks to explore as desired. But the core point is that fermentation is a very useful and unique method of food preservation, one that doesn’t require as much work or equipment or energy as many other methods, and which can even improve the food in question (something rarely said of freezing in particular). So it’s worth trying if you’re feeling adventurous or just like the idea of making real sauerkraut for once.

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