This probably won’t come as a surprise, but I’m a bit of a science nerd. I think this is why the job description of “registered dietitian” fits me perfectly: nutrition is just edible science.

Cooking is a giant chemistry experiment (for example, here’s why roasted broccoli tastes so good). Fermentation is a lesson in biology. It’s the latter we’re exploring today. We’re exploring this both because I love to ferment things, but also because a couple of weeks ago we came home with a literal trunkload of vegetables from our visit to Miller Farms’ Fall Festival. I just hate to waste food, but there was no way we could eat everything. Thus, I turned to the wisdom of my ancestors and their brilliant preservation techniques and retrieved my fermentation jar from the pantry.

Food Safety

Disclaimer: If you’re new to the art of fermentation, I recommend reading up a bit about the process online here or here, or by purchasing a pickling book. Science Friday also has a great interview with the author of The Art of Fermentation that explains a little more about the process and answers a few questions. It’s unlikely you’ll get food poisoning from fermenting your own vegetables, but good to know what to watch for just in case.

A couple of quick food-safety tips:

• Always follow the recipe: salt, vinegar, and sugar all help prevent bad bacteria from spoiling your food. Reducing or changing these quantities could mean bad news bears for your fermentation. If you really need a low-sodium diet, better stay away from these recipes.

• Don’t use plastic or metal. Plastic is easily scratched and bacteria loooove to hang out in these crevices, which can also ruin your delicious fermentation. Contaminants or chemicals from metal containers can sometimes leach into your fermentation. Glass or ceramic containers are much better options and are much more easily sanitized (just make sure your ceramic container doesn’t contain traces of metal).

• Wash. your. hands. And equipment. Thoroughly. With boiling water (your equipment, not your hands). Not sure it’s clean enough? Clean it again. At best, contaminated equipment will make your fermented products taste gross. At worst, you’re growing a science experiment you never wanted.

• Use common sense: If you notice your fermented food has an off-odor or you see signs of a bulging lid in your canned food, DO NOT EAT IT! Generally, fermenting food is really safe, but it’s not foolproof. Do your research and when in doubt throw it out!

Fermentation

Fermentation is the process by which bacteria or yeast transform one food into another food. In addition, the bacteria that ferment your food are also really healthy for your gut — ever heard of probiotics? The trick to keeping away harmful bacteria and only allowing the good ones to work is to add salt to your food before fermenting.

It might be a little hard to wrap your mind around fermentation (essentially the art of letting your food spoil), as we’ve been trained to use anti-bacterial hand soap and live in a world without germs (as if that were possible). In reality, we eat fermented food all the time. These are a few common examples:

• Some types of cheese (blue cheese, cheddar, and feta, to name a few)

• Beer, wine, and liquor

• Yogurt and kefir

• Sourdough bread

• Vinegar

• Kombucha

Let’s Ferment

I’m pumped to share this recipe for super easy home-fermented sauerkraut. If this is your first time fermenting, it’s a good recipe to start with because you literally only need 3 ingredients: cabbage, salt, and water. Homemade sauerkraut is fermented using natural yeast from the environment, so you don’t even need to add any to start with! So cool.

Start with a giant head of cabbage — about five pounds. Peel off any limp or damaged outer leaves and wash thoroughly. Cut cabbage in half, slicing through the stem, then cut “V” shape around stem and discard. Keep the layers of the cabbage stacked together as you cut. Lay flat side down and cut into very thin strips. Turn cabbage a quarter-turn and cut strips into thirds.

Add cabbage to a large, clean bowl and toss with five tablespoons of non-iodized pickling salt to coat evenly. Pack the salted cabbage tightly into a ceramic crock or glass gallon jar, then fill to almost the top with water. Leave about 1 inch of space at the top to place a plastic baggie half-filled with water. Place this baggie inside the rim of the jar to push down the cabbage so it’s completely submerged. Don’t put a lid on your jar — remember, you want oxygen to be able to get in so that the fermentation process is aerobic.

Now, let nature do its thang. Set your pre-sauerkraut in a cool, dark place. And wait.

Check the sauerkraut in 24 hours to make sure that all of the cabbage is still submerged. If not, mix up a brine made of one cup of water plus one tablespoon of salt. Add enough brine to cover the cabbage. You should notice tiny bubbles coming up to the surface — this means that the natural yeasts are doing their job and transforming your cabbage into sauerkraut! If a scum appears at the top, don’t fear. This is perfectly harmless, and you can just scoop it out with a spoon.

Check on the sauerkraut every few days. It should be fully fermented in about one to two weeks at room temperature, or about three to four weeks in a cool basement. You’ll know its finished because you won’t see any more bubbles rising to the surface and the kraut will be a pale, gold color.

And there you are! Your very own homemade probiotic goodness. Store your kraut in the refrigerator for up to a month. Eat your cabbage raw if possible, as heat will kill all of those healthy bacteria. Just gobble up all of this sour, salty goodness as soon as you can!

Enjoy!

Fermented Sauerkraut

Ingredients

• 5 lbs cabbage (1 large head or 2 small)

• 5 Tbsp. pickling salt (non-iodized)

• Water to fill the jar

Instructions:

1. Peel off limp or damaged outer leaves from cabbage and wash thoroughly. Cut cabbage in half, slicing through the stem, then cut “V” shape around stem and discard. Keep the layers of the cabbage stacked together as you cut. Lay flat side down and cut into very thin strips. Turn cabbage a quarter-turn and cut strips into thirds.

2. Add cabbage to a large, clean bowl (glass or ceramic) and toss with salt to coat evenly. Pack cabbage tightly into a ceramic crock or glass gallon jar, then fill with water. Leave about 1 inch of space at the top to place a plastic baggie half-filled with water. Place this baggie inside the rim of the jar to push down the cabbage so it’s completely submerged. Don’t put a lid on the jar.

3. Set your pre-sauerkraut in a cool, dark place.

4. Check the sauerkraut in 24 hours to make sure that all of the cabbage is still submerged. If not, add enough brine to cover the cabbage (brine should be made of one cup of water plus one tablespoon of salt).

5. Check on the sauerkraut every few days. It should be fully fermented in about one to two weeks at room temperature, or about three to four weeks if in a cool basement. It is finished no more bubbles rise to the surface and the kraut is a pale, gold color. Store sauerkraut in the refrigerator up to a month.