Autumn Anaerobes

by Holly McKelvey

Autumn – there's only one thing for it: Sauerkraut. That's what you thought I was going to say, right? Right.

Because when the days are long, and the afternoons turn dusty warm, produce is at its peak.  The fruits and veggies at your local farmers market won’t taste this fresh and rich for another year.

So, it’s time to get elbow deep in jars of briney water and ferment some harvest goodies to enjoy all winter long.

Fermentation has been cropping up in human diets for thousands of years. It involves harnessing the power of bacteria, yeast, and other micro-organisms to break down carbohydrates (sugars and starches) found in your fruits and veggies. These carbs are converted into acids or alcohol: a perfect preservative medium for your food.

The preservative nature of fermentation, like modern pasteurization techniques, keeps bad bacteria out. Pasteurization does this by heating and killing 99.99% of the microscopic creatures present; fermentation does it by creating a bacteria-rich environment that is hospitable only to harmless bacteria - preventing bad micro-organisms from taking root.

The bacteria that grow in sauerkraut are called lactic acid bacteria (which I shall refer to henceforth as lactobacs), and they occur naturally on the surface of cabbage leaves and many other veggies. They thrive on the carbohydrates available in plant tissue, converting them into lactic acid: a tasty kind of acid, similar to vinegar, that lends a sour edge to ferments.

Lactobacs do best in water and away from air, which is why you see sauerkrauts and other fermented foods submerged under liquid inside sealed jars. Sealing up ferments this way not only keeps out molds and other micro-organisms that need oxygen to grow; it also allows the lactobacs to convert their surroundings into an acidic paradise, to the point that it becomes unlivable for virtually any other micro-organism.

Think of these bacteria as a mafia family: they do everything they can to make things comfortable for their own, and uncomfortable for everyone else.

In this case, "comfortable" means acidic: an environment that is predominantly lactic acid. Over the course of a fermenting sauerkraut's first few days and weeks, its pH drops from a slightly acidic 5.5 or 6 down to a very very acidic 4.5 or lower. The presence of other micro-organisms drops precipitously during this process until the only surviving bacteria are - you guessed it - lactobacs.

As population of lactobacs explodes, the production of lactic acid increases: heralding that pungent sour taste we expect from a well-developed kraut.

So these lactobacs create a vinegary haven for themselves and nothing else: but what makes up their liquid world? In many types of ferment, veggies are simply submerged in a briney solution of water and salt. In the case of sauerkraut, dry salt is added to shredded cabbage leaves. The salt draws out water from the leaves, creating a salty brine.

This brine, a combination of salt and the cabbage's own sweat, provides the medium for growth that its native lactobac populations need.

The salt plays other roles, too. It makes the sauerkraut environment even more unattractive to other bacteria and micro-organisms: they are limited now not only by lack of oxygen, but also by their inability to tolerate salt.

So now that you know what's happening under the microscope, dive in! Get that fresh summer cabbage at your local market, and start sauerkraut-ing. This baby will last you through the long winter months as you find yourself struggling to remember the elusive warmth of summertime, and it'll get you appreciating the microbiota that thrive invisibly around you, and make your food so darned tasty.

RECIPE

1. Take one head of cabbage: slice it, shred it, cut it into little itty bits. The smaller the pieces, the more surface area across which osmosis can occur.

2. Put the shredded cabbage in a large bowl; sprinkle about 2 Tbsp salt on it. Gently squeeze the cabbage, massaging the salt into it. Almost immediately, water will appear. Keep on massaging for about 15 minutes. If you are adding anything in (see below), add that halfway through this stage.

3. Put it in a jar! Make sure the cabbage is fully submerged; if there's not enough liquid, add some water. Cover it either with a cheesecloth or seal it in a crock jar from which pressure can escape (CO2 production is highest during the early stage).

4. Let it sit for about 2 weeks, tasting it periodically - when it tastes awesome, start eating! You can keep it at room temperature or refrigerated. Refrigeration will pretty much stop fermentation, so flavor will not change much; or if you leave it out, you can see how flavor develops over a longer period of time.

Bonus: Add stuff! Honestly, sauerkraut can become your personal gastronomical playground when it comes to adding spices, herbs, and other veggies. Try different amounts, different combos, different varieties of each ingredient. Here are a few of my faves.

                        CLASSIC SAUERKRAUT     CURRY KRAUT                GINGER KRAUT

                         1 head cabbage                  1 head cabbage                1 head cabbage

                         1 1/2 tbsp salt                   1 1/2 tbsp salt                    1 1/2 tbsp salt

                         1 tbsp caraway seeds        4-5 carrots                         4-5 carrot2

                         5 cloves of garlic               ~1 inch of ginger root        3 tsp curry powder                            

Holly McKelvey is a graduate student in Applied Ecology at the Université de Poitiers, France, working on bio-indicators in stream ecology. She can be reached at holly.mc.kelvey@etu.univ-poitiers.fr