For Fermentation, We Love E-Jen Containers

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three sizes of fermentation containers on a marble countertop
Serious Eats / Grace Kelly

Sweet pickles, sour pickles, sauerkraut, kimchi—I love fermented foods. Any vegetable long-cured in salt or vinegar and aromatics so that it’s tangy and snappy, i.e. the perfect accompaniment to rich meats and strong martinis, is the right condiment for me. But, as a food writer and home cook who prides herself on her skills in the kitchen, I was crestfallen when I started working on a cookbook with my friend Scott Clark and my first attempts to recreate his kimchi failed. Two times, I ended up with a layer of black, spoiled stuff on top with a gallon of cabbage and other vegetables, seasonings, and salted shrimp beneath it that showed no discernable bubbling. The lactobacillus—the beneficial bacteria that create the lactic acid that ferments the kimchi—had no signs of life.

I should have followed my pal’s advice all along. Clark, chef-owner Dad’s Luncheonette in Half Moon Bay, makes his kimchi in what he likes to call his “kimchi briefcase,” a snap-locked fermentation container by the Korean company E-Jen. A modern, plastic version of a traditional Korean earthenware crock, or onggi, the E-Jen container I bought worked like a charm, taking no effort at all to create the perfect environment that leads to successful lacto-fermentation.

The key to E-Jen’s foolproof fermenting is its inner airlock. Dubbed by E-Jen a “vacuum intercept board,” this adjustable inside plunger completely covers the fermenting foods, ensuring that no oxygen gets inside. That’s essential for lacto-fermentation. As Dr. Julia Skinner, author of Our Fermented Lives, explains, “When fresh vegetables are packed into a jar with brine, the naturally-occuring bacteria on the vegetables begin to ferment the vegetables, eating the starches they contain and, as they do so, softening the veggies and acidifying the brine. The combination of salt and this acidity makes the brine inhospitable to pathogenic microbes. Lactofermentation is anaerobic, which means it happens without oxygen, so keeping your veggies completely submerged helps ensure you’re only getting the microbes you want in the mix.”

kimchi in a fermentation container
Serious Eats / Grace Kelly

Knowing I needed to push the vegetables down into the brine to keep out as much oxygen and unhelpful bacteria as I could, I had been dutiful with my original setup. I had bought the round, glass fermentation weights and the bulky fermentation lids that you’re supposed to use when your fermentation vessel is an over-sized Ball jar. But the weights didn’t completely cover the surface of the kimchi, and the lid wasn’t a perfect fit. Plenty of experts will tell you can use whatever vessels you have around. In truth, it’s hard to get it right when you’re retro-fitting Ball jars. Because of this, I couldn’t achieve a perfectly anaerobic environment. 

This is because all fermentation vessels contain head space between the lid and the fermenting food inside. Oxygen exists in that space, as can harmful microbes. In order to ferment successfully, you must protect your foods from anything in the head space that might ruin your fermentation. In some Korean homes, like her mother’s house, says caterer Sung Kim, cabbage leaves, sometimes aided by a weight laid on top, are placed over the kimchi in order to completely cover the ingredients and keep them submerged in the brine. At the end of the fermentation, you simply remove and compost those leaves. 

a fermentation container on the shelf of a fridge
Serious Eats / Grace Kelly

The E-Jen, I found, encased the kimchi just as effectively, without my having to go to any extra steps. The E-Jen’s removable inner plate features an air nozzle at its center and a silicon vacuum seal around its edges. To use the plate, I pushed the air nozzle into place, pressed the plate down snuggly over the kimchi, and pulled the air nozzle out to expel the air and create an airlock. Then I replaced the nozzle again, and the plate kept it protected from oxygen and sunk below the surface of the brine. Forget the extra weights and lids. “The E-Jen is an all-in-one package,” Clark says. “It has the airlock already on there. There’s no need for buying all this extra stuff.”

Fill the box, press on the airlock, snap the exterior lid into place, and the fermentation is good to go. Easy. The airlock wasn’t a barrier to the frequent tasting I wanted to do to figure out when my kimchi was fermented to my liking. I had purchased a larger E-Jen, and those models, sized 1.9 to 4.4 gallons, include a detachable inner cap in the “vacuum intercept board” that I could remove temporarily to access my kimchi. Some models are also equipped with handles for easy carrying. After one week in a cool, dark cabinet, my kimchi came out tangy and spicy and fragrant, ready to pop in the fridge for use on rice dishes, in stews and soups, and piled onto sandwiches.

I needed that success. After a couple of failures, I had almost given up on kimchi. That, according to Samantha Paone, owner and culinary director of Golden State Pickle Works, would have been a shame. A fermentation booster, she says, “I tell people when they come to me for guidance: Keep trying, don’t give up. The more you practice something, the better you become so please don’t get discouraged.”

I knew from Clark that an E-Jen would work, but I had been reluctant to order one because they are made of plastic. After all, experts like Paone say, “Producing a plastic box for this specific age-old technique is unnecessary when there are so many fermentation-friendly vessels stacked up in the corners of our homes,” including Ball jars and crocks. But my Ball jars had failed me. 

Plastic can have its problems. “Plastic is not a good conductor of temperature, so it tends to accelerate the fermentation process, which could potentially contribute to faster spoilage, especially if the environment is too warm,” says Kim. But I found that this wasn’t an issue in the cool spot where I kept the box. And, unlike a clear glass Ball jar, the brown plastic E-Jen also kept out light, which can otherwise affect fermentation.

Skinner dislikes plastic because of the way it can hold smells. Clark has an easy solution for that: Keep one E-Jen to always use for kimchi, keep another for sauerkraut, and so on. So now I have two E-Jens, a small one for sauerkraut and a bigger one for the batches of kimchi I’ve regularly started to make. They’re inexpensive enough that it wasn’t a hardship for me to buy two. However, if you must use your E-Jen for more than one type of ferment, Clark has a trick for removing old odors: “Rub butter on the inside of the vessel, then use Dawn dish detergent to wash it,” he says. “It’s the same thing for spaghetti sauce in a Tupperware. Rub it with butter and then hot dish soap, and that pulls all the smells because they’re transferring to all that grease and being removed when you scrub the butter out.” 

Even if you’re using one E-Jen exclusively for one purpose, you want to make sure it’s cleaned and dried correctly so that no bad bacteria grows inside of it, waiting to ruin your next batch of kimchi. To that end, the E-Jen is dishwasher safe. If you’re washing it by hand, use hot, soapy water, and dry it thoroughly after machine- or hand-washing. Remove the silicon vacuum seal from around the airlock plate first, so you can wash and dry it separately. 

It can be a bit tricky to fit the silicon seal back in. Make sure it is tucked completely into the groove on the airlock plate, all the way around. For cleaning purposes, Skinner has good advice for dealing with crevices. “I find, with airlocks, it can be helpful to have a pipe cleaner or bottle brush to help clean out the inside,” she says. And, if you take a bit of time before you use your E-Jen again, wash and dry it just before re-use to ensure it’s sanitary.

Beyond kraut and kimchi, the E-Jen works for other fermented foods like soy sauce and hot sauce, and because it can handle hot temperatures up to 140°F and is refrigerator-safe, you can protect marinating meats as well as leftovers of all kinds from oxygen in an E-Jen. It even does the same in your pantry for cereals and other dry goods. 

Key Specs

  • Materials: Plastic
  • Dimensions: 7.09 x 6.1 x 4.29 inches – 13.5 x 9.5 x 11 inches
  • Weight: 15.2 oz – 4.34 lbs
  • Capacity: .45 – 4.4 gallons
  • Care: Dishwasher-safe
  • Price at time of publish: $17


How does lacto-fermentation work?

As Samantha Paone explains, “We ferment vegetables using salt as the preservative. Either we massage vegetables or place vegetables into a salt brine, and let that sit at room temperature. Over a couple of days, bacteria starts to grow. This bacteria produces a lactic acid that turns the vegetable into a pickle, all the while producing lactobacillus bacteria. Our salt content in the ferment invites the good bacteria (lactobacillus) to thrive, while not allowing the bad bacteria (E. coli and salmonella) to live. After some time, depending on environment and temperature, the acidity raises, pH lowers, and the vegetables are preserved and alive with probiotic bacteria.”

What are the benefits and drawbacks of an E-Jen container?

Unlike other vessels you might use, such as big Ball jars, E-Jen containers are made specifically for the purpose of lacto-fermentation. They contain an inner vacuum plate that seals the fermenting food off from oxygen and any harmful bacteria that exist in the head space between the plate and the lid. The design is pretty foolproof. The drawback is that the E-Jen is made of plastic, so they’re not as insulating as ceramic crocks. The plastic can also hold the strong odors of fermentation, even after washing. There are ways to overcome these obstacles, though.

How do you clean an E-jen container?

Use a dishwasher or hot, soapy water. Pull the silicon vacuum seal out of its groove in the airlock plate, and wash it separately, running a pipe cleaner through the groove to clean it, too. Dry the E-Jen thoroughly. It’s best to keep one specifically for kimchi, as the strong odor of the fermentation will affect the smell of the plastic. 

What size E-jen container should I buy?

That depends on how big a batch of kimchi you want to make. The smallest E-Jen holds .45 gallons, or a little less than two quarts. It might take time to eat that much, but your kimchi will last in the fridge. It won’t stop fermenting altogether, but the cold inhibits fermentation quite a bit, so it will keep for at least three months. The problem with the smallest E-Jen is that you really have to pack in the ingredients, risking spillover. You can give yourself more maneuvering room with a medium-sized E-Jen, like the 1.3-gallon size.

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