Want to add depth to your fruits and vegetables? There’s a ferment for that

Katherine Harmon Courage

THE WASHINGTON POST – The proposition sounds a little dubious: Leave some vegetables in a jar on your counter. Just leave them there. For weeks. Then eat them. It’s perfectly safe, say the pickling enthusiasts. They’re great for you. You’ll love them! they say.

Not convinced? Science is here to explain why fermenting vegetables is not only perfectly safe but also surprisingly easy and rewarding. Spoiler: Microbes do most of the work.

In our hyper-Pasteurian, expiration date-driven era, it might be difficult to relinquish control over our food to these mysterious forces. But a small measure of understanding yields rich rewards: Crisp classic sauerkraut, warmly tart beets, bright preserved lemons and just about anything else you can dream up.

These classically preserved foods and so many others – from kimchi to kombucha – have been expanding their footprint on cooler shelves in supermarkets and even on some restaurant menus. In part, we have to thank for this the proliferation of new research on gut health and the outsize role beneficial microbes (which are bountiful in fermented foods) play in helping our gut, immune and overall health.

As the probiotic-driven food trend has accelerated, many chefs and consumers have also rediscovered a new world of flavour and texture that has long been missing from United States (US) tables. We might have a sepia-style image of sauerkraut fermenting in large wooden barrels in Northeastern Europe. Or a vague notion of preserved lemons pepping up a warm Middle Eastern grain salad. But this style of food preparation can incorporate just about any produce you might find at the market – or languishing in your crisper drawer – and unexpected seasonings, such as spiced fermented beets.

Pickled lemons and beets. PHOTO: THE WASHINGTON POST

Many of us grew up with shelf-stable pickles and krauts, which stay that way through a combination of vinegar and pasteurisation. These two processes are ruthlessly effective in killing off harmful microbes. But they also zap the helpful ones.

Produce is naturally covered in microbes. For thousands of years, people have relied upon these unseen life-forms that to create myriad delicious, nuanced non-vinegar ferments, often called “wild ferments.”

The process is quite simple: Salt, submerge, wait. And eat.

Why does this method work so reliably? Salt kills harmful microbes and encourages beneficial ones, such as those that produce lactic acid, which are similar to many found in the gut microbiome. Similarly, submerging the produce in liquid (whether added or extracted from the food itself) protects it from the less-desirables.

And, the process offers further safety measures. As fermentation gets underway, the ascendant bacteria begin to alter the overall environment. They consume some of the carbohydrates from the produce, creating carbon dioxide (which appears as bubbles) and, more important for our purposes, lactic acid (which lowers the pH).

“The process is self-protecting,” explained fermentation expert Sandor Katz, who is the author of The Art of Fermentation, among other books about the craft.

“Statistically, fermentation makes vegetables safer than they are raw,” he said.

“It’s pretty bomb-proof,” agreed co-founder of the fermented food company Ozuké Mara King. “As soon as you achieve something that is pretty sour, it is safe.”

Food regulations deem fermented food safe at or below a pH of 4.6. For comparison, a lemon has a pH of two to three. If you are sceptical about ballparking the sourness with a lemon-taste test, King suggests purchasing inexpensive paper pH test strips (remember those from high school chemistry class?) or investing in a pH meter.

As hands-off as the process seems, there are ways we can steer the bacteria to do their best work.

One method is through temperature. A warmer environment will encourage more bacteria to thrive more rapidly and will result in a faster ferment. A cooler environment will have the opposite effect (which is why we hold “finished” ferments in the fridge for longer-term keeping).

Generally, 65 to 70 degrees Fahrenheit is an effective range for most vegetable ferments. We can also nudge the fermentation duration forward or backward with salt concentration – less salt for a faster ferment; more salt for a slower one.

Time is the final and most powerful variable. Over time, the flavour and texture of the produce shift toward the acidic and soft, respectively. Which is why Katz recommends “tasting at intervals.”

Tasting also provides a reminder to keep tabs on ferments.

Although the microbes might be doing most of the work, it is important to ensure ferments remains submerged. An exposed piece of produce is inviting real estate for yeast and mould that need air to flourish.

But fear not if your ferments gain a bit of a surface growth – most frequently kahm yeast or a fuzzy mould. It’s fine. Really.

“Remove it as best you can, and don’t worry if some dissipates into your brine,” Katz said. The salt and acidity will protect the rest of the ferment. (Watch for a bright, colourful mould. That could be hazardous. But in the decades of his work and travels, Katz has never seen a dangerous mould on fermenting vegetables.)

Despite what our 21st Century instincts might say, in the compendium of food preparation methods, lactic-acid fermentation is among the most forgiving. It’s also healthful – and enthralling.

“I love the alchemical magic of the process,” Katz said. And the science, too.


Active: Five minutes | Total: Five minutes, plus fermenting time. Four to eight servings (makes four preserved lemons).

Bright and briny, these preserved lemons make a flavourful addition to cooked grains, roasted chicken, stew or soups.

Make ahead: The lemons need to be prepared at least three weeks before you will use them.

Storage notes: Store the lemons refrigerated in a jar with a lid, ideally submerged, for six months and up to one year.


Five small, organic and preferably unwaxed lemons (about one pound)

Five teaspoons kosher salt, divided, or more as needed

One cup water, or more as needed


Make a deep “x” incision in four of the lemons, leaving about a quarter-inch intact at the bottom of each fruit, so it almost opens like a flower. Pack about one teaspoon salt into each lemon, getting it between the sections.

Pack the salted lemons into a wide-mouth jar just large enough to hold the lemons, squishing them down with clean hands to yield as much liquid as possible. Juice the remaining lemon; you will need about a quarter cup of juice. Dissolve one teaspoon of salt in one cup of water; then add the juice. Pour the brine over the lemons until they are completely submerged, then weigh the lemons down with a heavy stone or water-filled plastic bag. (If you don’t have enough liquid to cover the lemons in the jar, you can mix one teaspoon of salt per one cup of water, and add as needed.)

Cover and place in a moderately cool location, about 65 to 70 degrees. (If using a lid, be sure to “burp” the jar regularly – preferably before it shows signs of bulging. Or use cheesecloth or an airlock fermenting lid, which will allow microbe-created gas to escape while keeping outside air from entering. If using cheesecloth, you do not need to cover with lid.)

Taste the lemons after three weeks, and weekly thereafter, to determine readiness. They will remain a saturated yellow and will taste bright, salty and sour – including the peel.

Ingredients are too variable for a meaningful nutritional analysis.


Active: 10 minutes | Total: 10 minutes, plus fermenting time. Eight to 16 servings (makes four cups).

These striking, ruby-red beets retain their beautiful hue and add crunch and flavour to whatever you are eating. Try tossing them into a winter salad of endive, sliced apples and chopped almonds.

Note: If you don’t have enough liquid to cover the beets in the jar, dissolve one and a half teaspoons of salt in one cup of water, and add as needed.

Make ahead: The beets should be made at least two weeks ahead of consumption.

Storage notes: Store refrigerated in a jar with a lid for up to two months. Keeping the beets submerged will help them stay good longer.


One pound beets, trimmed and scrubbed

One and a half teaspoons kosher salt, or more as needed

One cup water, or more as needed

One cinnamon stick (or other equivalent seasoning, such as cardamom seeds)

Extra-virgin olive oil, for serving

Freshly cracked black pepper, for serving


Slice the beets into a quarter-inch-thick rounds. If the beets are wider than the jar, cut the slices into half-moons.

Dissolve the salt into water at a ratio of one and a half teaspoon salt to one cup water – scaling up, if necessary.

Pack a wide-mouth jar with half of the beet slices. Add the cinnamon stick, followed by the remaining beet slices to the jar. Pour the salt water over the beets until fully covered. If any of the beets are floating, weigh them down with a heavy stone or water-filled plastic bag.

Cover and place in a moderately cool location, about 65 to 70 degrees for about two weeks. If using a lid, be sure to “burp” the jar regularly – ideally before it shows any signs of bulging. Due to the high sugar content of beets, they ferment quickly and can cause a mess if excess pressure builds up in the jar. Alternately, use cheesecloth or an airlock fermenting lid, which allows carbon dioxide from the microbes to escape but does not allow outside air to enter. If using cheesecloth, you do not need to cover with a lid.

After two weeks, taste the beets weekly to determine readiness – a shorter ferment will yield earthy, crunchy beets, whereas more time will make them softer and more warmly spiced. Red beets will retain much of their vibrant colour.

Serve, drizzled with mild olive oil and a twist of fresh-cracked black pepper.

Ingredients are too variable for a meaningful nutritional analysis.