The Science of Brining Vegetables

In the recipe development world, it often seems like there’s no problem that brining can’t solve. Dry, chalky chicken? Bland, overcooked salmon? Unevenly cooked, wrinkly beans? Brining makes all your problems go away.

Beyond beans, brining is known to work for some specific types of vegetables. Salting eggplant before cooking, for instance, is a long practiced method, and salting cabbage, cucumbers, and other water-rich vegetables is commonly employed for salads, pickles, and more. For the most part, brining is meant to drive water out of these items, concentrating flavor and firming up their otherwise floppy texture—or conversely, softening some vegetables to tenderize them.

But is that where vegetable brining ends? Is there a place for brining other vegetables, like the more waxy, dry, and starchy options—things like broccoli, cauliflower, carrots, winter squash, green beans, or potatoes? I’d wager that most people don’t brine these items before throwing them in the oven or on the grill. But should they be brined? I got to testing to find out.

Defining "Brine"

By the strictest definition, a brine is a solution of salt and water. In modern cooking parlance, brining has expanded to mean simply treating foods with salt for a period of time—either with a “wet” brine (saltwater solution) or a “dry” brine (just salt). Dry brines manage to act as brines by drawing water out of the ingredient and then dissolving into it, forming a wet brine with the ingredient's natural moisture. (Brines can also include sugar, but for the purposes of this discussion—and simplicity—let’s just stick to salt.)  

Which Vegetables Are Good for Brining?

A Question of Water Content

For meats and fish, the benefits of brining are clear: Salt not only penetrates the tissue and seasons it, but it also enhances texture by dissolving proteins (like myosin), preventing them from contracting as much during cooking. Limited contraction means the meat holds on to more water, so it tastes juicier and more tender.  

But vegetables don’t have any of the filamentous (fibrous) proteins that make meat, well, meat. There’s no dissolving of proteins or tenderizing going on here. Instead, vegetables contain polysaccharides like cellulose and pectin, sugars, and many other starches, among other components. Most importantly, vegetables have cell walls which are semi-permeable to salt and water. 

Salt tends to move away from areas of high concentration to areas of low concentration across a cell membrane in a process known as diffusion. And together with osmosis—the movement of water from areas of lower (salt) concentration to areas of higher concentration—these processes are crucial for preparing vegetables like cucumbers for pickling, or cabbage for sauerkraut or kimchi. Osmosis drives water out of the plants’ cell membranes, while salt diffuses across those membranes and seasons the vegetables deeply. 

That’s all well and good if you’re a high-water content vegetable without much of a tough exterior. But what about the rest? Consider the following table:

Most people don’t usually brine these vegetables. Why? Maybe because they are perceived as “drier.” Certainly vegetables like sweet potatoes, potatoes, or carrots have a lower relative water content. On the flip side, broccoli and cauliflower are over 90 percent water. Meanwhile, eggplant is about 90 percent water. So what makes eggplant a worthier candidate for salting or brining than, say, broccoli?    

The truth is, I don’t know the reason. But clearly, water percentage is not the only part of this story.

A Question of "Waxy" Skins and Peels

If water content isn't a good predictor of a vegetable's affinity for brining, is it possible it has to do with the nature of the vegetable's peel and flesh? Are "waxy" vegetables less appropriate for brining?

When we say “waxy” vegetables, we refer to vegetables that don’t seem permeable to water. But the truth is that most vegetables—even the ones we typically do brine, like eggplant and cucumbers—have a skin (or epidermis) and a layer of epicuticular wax, a naturally occurring, water-repelling substance on the outermost layers of vegetables and fruits that prevents water loss and potential harm from pathogens. This feature is most apparent with foods like carrots or winter squash, but it's present in most vegetables. You can also see epicuticular wax at work in the leaves of uncut kale, as water beads up and runs off them in the rain or under the faucet.

For the most part, we peel or cut vegetables to access the flesh beneath. And in order to brine, peeling, cutting, or physically breaking the plant’s cells (think smashing cucumbers, or thinly slicing and then massaging cabbage) are essential steps for success. It seems that even here, there are no easy rules about a vegetable's peel that might provide a hint as to whether it's good to brine or not, since peeling and cutting are routine parts of prep in many vegetable brining situations.

The Testing: Brining Every Vegetable in Sight

Here’s my hypothesis: Under the right conditions, you can brine any vegetable in a solution of salt and water; given enough time and a high enough salt concentration, you will observe some positive difference in seasoning and/or texture.

To test, I submerged various vegetables in a 5% salt solution for varying lengths of time. For vegetables with a defined skin, I peeled or cut them to expose the inner flesh and maximize any chances of salt transfer. I then drained the vegetables and cooked them, either by roasting, broiling, or some other heat treatment. I weighed each sample before and after brining to measure any water loss (or gain?), and evaluated everything for taste and texture.

I repeated this testing for 8% and 10% brines.

Here are the results, highlighting a few vegetables:

Green Beans

Green beans have a leathery exterior that seems to repel water. Because of this, I opted to trim the ends of each bean to facilitate easier transport of water/salt into the beans. (I even halved some crosswise to compare any differences, though it didn’t seem to matter in the end.) After brining, I drained the green beans, tossed them in a measured amount of oil, and broiled them for exactly seven minutes.

Across the board, the beans tasted saltier as brining time increased. Interestingly, longer-brined beans tended to cook faster and wilt more than shorter-brined beans. Why? You’ll notice that as brining time increased, the beans seemed to lose water weight. Water is what keeps plant cells crisp (turgid), and the cooking process drives water out of those cells. I suspect that longer-brined green beans had less water prior to cooking, so wilting happened more quickly.

The verdict: Were brined beans objectively better than un-brined beans? Across all salt concentrations, on the extreme end (12 hours), I’d say no; the beans just got too salty and became too wilty. But around one to four hours—especially at the eight percent concentration—the level of seasoning was ideal, and compared to longer-brined beans, they didn’t wilt so dramatically, retaining a bit of their color and structure through broiling. I’d say that’s a win for brining—especially for high-heat applications where you might want to retain some crisp-tender bite.

Russet Potatoes

Here I left potatoes unpeeled, cut them into 2-inch chunks, then brined them. After brining, I coated the potatoes in oil and air fried them at 400°F for 30 minutes.

Brined cut potatoes took on plenty of salt as time elapsed, with a sweet spot between 30 minutes and four hours. Like green beans, the 12-hour brined samples were aggressively salty. And again, the potatoes appeared to lose water weight over time—as much as 10 percent after 12 hours.

Texturally, brined potatoes had a creamier texture as time elapsed. By comparison, unbrined potatoes were fluffier and more starchy. But how much of that difference comes from salt? After all, soaking potatoes in water is a common practice intended to give foods like french fries a creamier cooked texture. To nip this in the bud, I ran an additional test comparing potatoes brined for 12 hours versus potatoes soaked in water only for 12 hours. As expected, the resulting textures were nearly identical—so the salt is primarily adding seasoning, while the water alters the texture.

The verdict: If you want creamier, more evenly seasoned potatoes, then brining is beneficial. I suggest a 5% to 8% brine for at least 30 minutes and up to four hours for optimal results.

Broccoli and Cauliflower Crowns

Cruciferous vegetables are a tricky case for brining. While the stems are waxy and seemingly impervious to water, the florets are porous, presumably trapping some brine between the buds. That means that at minimum, we might expect brined florets (of any duration) to be more seasoned than unbrined florets; it also raises the question of whether this type of vegetable can be brined evenly, or whether the process results in florets that are seasoned differently from the stem sections.

First, I ran this test with whole crowns, only trimming away the thickest bottom stems, then submerging the crowns in brine. I repeated the tests with separated florets as well. After brining, I coated the vegetables in oil and roasted each sample at 400°F and evaluated.

Across all cases, I didn’t see much moisture loss. I attribute this to the fact that I wasn’t really peeling or exposing much of the flesh beneath the protective periderm. Alternatively, it’s possible that water was trapped in the florets between individual buds. As for taste, there was little to no seasoning in the cauliflower samples brined up to one hour. At four hours, the benefits were more noticeable—good salt penetration to the deeper parts of the florets, and acceptable seasoning at the stems. At 12 hours, the salt level was just too much.

I saw similar results for broccoli crowns: virtually no seasoning after 30 minutes, minimal seasoning up to one hour, and ideal seasoning around four hours. This time, salt penetration into the broccoli florets seemed deeper than cauliflower. My guess is that the florets were less tightly spaced in broccoli than cauliflower, allowing more brine to seep into the spaces over time.

Separated, individual florets had slightly more seasoning across all tests. As expected, cutting and separating exposed more of the interior plant cells, which probably allowed more contact with brine. Here, one hour was sufficient for discernible benefits.

Texturally, I saw no major differences between unbrined and brined samples. But the big advantage was flavor: Brined samples tasted more vegetal, slightly sweeter, more like themselves.

The verdict: For more evenly seasoned, less bitter, sweeter tasting cruciferous vegetables, brine whole crowns for around four hours in a 5% to 10% brine before cooking. If you’re in a hurry, you can separate broccoli or cauliflower crowns into individual florets to speed up salt penetration, and brine for up to one hour.

Sweet Potatoes

Sweet potatoes have the lowest water content of all vegetables I tested. I peeled, cut, and brined 1 ½-inch chunks, then roasted them at 400°F for 30 minutes. Even after 12 hours of brining, there was minimal moisture loss. Texturally, longer brined sweet potatoes had a creamier interior than shorter brined samples—just like russet potatoes. Unbrined sweet potatoes also tended to brown more quickly than all brined samples (this could be unrelated to the salt in brine and more to do with the brine's water washing away surface starches that are prone to quicker browning).    

The verdict: If you want creamier, well seasoned sweet potatoes, brining them for up to four hours in a 5% to 8% salt solution is optimal. Be sure to peel and cut the potatoes for optimal salt penetration.

Brussels Sprouts

Brussels sprouts are essentially mini cabbages. Their structure features overlapping leaves, which form random spaces between those leaves. Because of those nooks and crannies, we’d expect halved Brussels sprouts to hold onto more water if submerged in a brine. And for the most part, the results show this: Regardless of duration, all samples gained weight after brining.

After brining, I coated the Brussels sprouts in oil, then air fried them for 30 minutes at 425°F. In terms of taste and texture, I didn’t see much benefit until at least one hour of brining at all salt concentrations. Brussels sprouts brined for 30 minutes showed uneven browning, a more bitter, vegetal flavor with a raw mustard finish; they also had more crunch and rawness.

In contrast, longer brined sprouts were saltier, creamier in texture, sweeter, less bitter, and surprisingly, had more even browning. Why more even browning? There’s some evidence that salt enhances the rate of browning in certain foods. Maybe salt facilitates more even browning in this case by drawing out initial moisture, but I don’t have enough evidence to say for sure.

The verdict: Brined Brussels sprouts are a win. Opt to halve them, then brine them in up to a 10 percent salt solution for at least one and up to four hours. When roasted, the Brussels sprouts are sweeter, less bitter, more evenly browned, and more tender-creamy than unbrined versions.

Other Vegetables

Other highlights in testing included carrots, kabocha squash, and butternut squash. These vegetables behaved similarly, and all benefited from at least one hour in brine.   

Limitations of Testing

Clearly, brining has a place in enhancing flavor and even the texture of certain vegetables. But it’s not a cure-all for every vegetable, and it’s difficult to make blanket statements. In general, I found optimal results brining between one and four hours at salt concentrations between five and eight percent.

For high-heat applications, brining tough vegetables like broccoli, cauliflower, and even green beans can be transformative. But I’ll admit, I didn’t test lower, slower, gentle cooking applications.

Finally, my testing wasn’t exhaustive. There are dozens of vegetables that I didn’t test. But hopefully I captured a wide swath of options across a range of vegetable types to give a general picture of possible benefits.

If You've Got Time, Put It in Brine

Vegetable cookery is often an afterthought. It can play second fiddle to more show-stopping mains or substantive dishes. So next time you’re marinating your steaks or brining your chicken breasts at the peak of a summer grilling season, consider brining some vegetables too. With a little planning, you can transform your broccoli from bland and bitter to tender, savory, and even sweet—just be sure to dry off any brined vegetables that you want to cook very quickly over high heat, since the excess water can slow browning.