brussels sprouts

Hello, I’m Andrea Castillo and this is Seasonal, a newsletter that connects you to the Bay Area food system, one fruit and vegetable at a time. Each post highlights the most interesting aspects of one seasonal fruit or vegetable grown and harvested around the Bay Area. Seasonal is a public good, and all past and future posts are free to read, but if you want to support my quest to deepen our connection to food and contribute to building a stronger food community, please consider becoming a paid subscriber for $5/month. Find me on Instagram at @seasonalbayarea or e-mail me at seasonal@substack.com to share your feedback and suggestions, I’d love to hear from you. If you’d like to unsubscribe, click the link at the bottom of this post.

This week, we nerd out on Brussels sprouts (available September - May).

Abuelitas, omas, or grandmas leave edible legacies. “The way grandma used to make it” sets the bar when we transform comforting memories from our childhood into meals in our kitchens. For example, part of my abuela’s legacy is her arroz con leche: the best rice pudding I’ve ever had. But every time I attempt to recreate her spiced-just-right arroz con leche, I fail. The the texture and flavors just aren’t quite right. 

grandma’s terrible cooking

While most of my abuela’s cooking was phenomenal, some of it I’d never make again. There were a few dishes, like ullucos (I swear I feel nauseous typing it now), an Andean tuber, that filled me with dread as a child. The mention or smell of them alone would send a signal to my kid brain to ready a tantrum. 

You may have never heard of ullucos before, but what about Brussels sprouts? Even though I did not grow up eating them, I’ve learned that some of my Western European and American friends may have similar dreadful childhood memories associated with these stinky, mushy, tiny cabbages. And it’s not just them. Brussels sprout disdain is a thing: Brussels sprouts is a top result after Googling “most hated vegetables.” What gives? Grandma’s cooking legacy is one of the core reasons behind the hate. 

Brussels sprouts are one of the newest vegetables to show up on our plates. Even though Brussels sprouts’ ancestors like cabbages, mustard greens, and cauliflower have been around for nearly 3,000 years, Brussels sprouts are at most 800 years old. We do not fully understand their history but we do know that Brussels sprouts grew throughout Belgium sometime between the 13th and 16th century and crossed over to France and England at the end of the 18th century.

the belgian boil

At that time, Brussels sprouts cooked the Belgian way meant they were boiled for an eternity and served with butter. As Brussels sprouts spread to British, French, and American tables, so did the overcooked boiled Brussels sprouts method. Over the past 200 years, boiling Brussels has become a divisive culinary legacy, somehow gaining enough fans to keep the tradition going but raking up plenty of haters who suffered through tantrum-inducing meals. 

With plenty of mushy Brussels sprouts resistance, especially from children, why did grandmothers’ grandmothers and their grandmothers opt for boiled? Why not pan-fried or roasted Brussels sprouts? Cabbage was pan fried in butter in the mid 1700s, so why not give its tiny relatives the same delicious treatment? By the 19th century, we already used skillets and baking pans so it’s not like we didn’t have the tools to branch out. Is there something unique about how boiling affects Brussels sprouts?

the science of boiling

Turns out there is. Whether omas and their omas knew it or not, boiling leverages chemistry to tame a rather unpleasant taste unique to Brussels sprouts.

Brussels sprouts and their family members deploy intense sulfur compounds that fend off unwanted pests looking for a bite to eat. You may recall from a previous edition of Seasonal that radishes, which are related to Brussels sprouts, are equipped with molecules known as glucosinolates that convert into pungent, spicy isothiocyanates in the attacker’s mouth to deter further eating.

Brussels sprouts have a similar defense mechanism, with a twist. Brussels sprouts are almost as gung-ho about defense budgets as the United States: the amount of glucosinolates in Brussels sprouts is five times what we find in radishes. If you’re curious to experience the Brussels sprout defense mechanism, just eat a handful of their raw, white cores… it’s intense!

In addition to that powerful kick, Brussels sprouts’ glucosinolates create bitterness that may overwhelm you depending on your genes and sensitivities. To make it worse, Brussels sprouts are packed with two distinct sources of bitterness. The first is sinigrin, a type of bitter glucosinolate that becomes less bitter when cooked slowly over time. The second is progoitrin, a non-bitter glucosinolate that needs to be cooked quickly to prevent it from converting into bitter-tasting compounds. No matter how you cook them, slow or quick, Brussels sprouts are bound to taste bitter.

With one exception.

To tame the intensity and bitterness in Brussels sprouts, guess what cooks resort to? Boiling. The heat in boiling water halts progoitrin in its tracks, preventing bitter flavors from forming. To achieve a chemical balance, boiling water pulls sinigrin from Brussels sprouts—especially when sliced in half because of a larger exposed surface area—leaving those bitter flavors in the water instead of the vegetables.

Boiling may take care of the double-trouble bitterness dilemma but it has serious drawbacks, which is perhaps why Brussels sprouts can get such a bad reputation: if you don’t boil them for long enough, they’re still bitter and pungent, but if you boil them too long, the delicate, tightly-packed leaves will overcook and disintegrate into a non-bitter but nutrient-devoid mush. As if that weren’t enough, boiled Brussels sprouts stink! Glucosinolates in Brussels sprouts have smelly sulfur compounds that escape into the air when boiled for more than five minutes, stinking up the kitchen with an unpleasant rotten egg scent. So, if boiled Brussels sprouts were part of your family’s edible traditions, just know that grandma or the cooks in your family weren’t trying to torture you. They probably had good intentions and were simply trying their best to tame this pungent, bitter vegetable.

Brussels sprouts: chock-full of glucosinolates and ready for a good roast.

parting ways with long boils and daring chefs

Never had a boiled Brussels sprout? Maybe the chefs in your family were adventurous and avoided boiling all together—lucky you! Or maybe you’re new to the vegetable and caught the relatively recent roasted Brussels sprout trend.

In the mid-2000s, chefs like David Chang un-mushed Brussels sprouts and roasted them to a new, crispy, caramelized level that people went nuts for. Famously, David Chang’s restaurant, Noodle Bar, would sell so many Brussels sprouts he had to take them off the menu at one point. Other restaurants offered similar versions of crispy Brussels sprouts and they caught on—even with kids! The mere 2,500 acres of land used to grow Brussels sprouts in the United States back then were too small to satisfy the sudden demand and by 2019, there were 10,000 acres dedicated to the newly popular tiny cabbage. Most American Brussels sprouts today grow in California. In fact, farms around the Bay Area—in San Mateo, Monterey, and Santa Cruz counties—grow almost all the Brussels sprouts in the country.

Farmers continue to plant more Brussels sprouts as they respond to the growing demand for the David-Chang-style Brussels sprouts. But how did chefs overcome the bitterness challenge? Roasting improved texture without a doubt. But roasting takes time, so wouldn’t the bitter progoitrin compounds linger? The whole point of boiling was to tame bitterness, so why did these new Brussels sprouts woo so many?

The short and simple answer is that Brussels sprouts are not as bitter as they used to be. Sure, the crowd-pleasing Brussels sprouts roasted with kimchee puree or tossed with fish sauce vinaigrette beat the old-school, soggy, boiled Brussels sprouts any day and a chef’s creative approach to rescuing a vegetable from a boiling cauldron deserves a lot of credit. But chefs in the past 20 years have been working with an entirely different vegetable than grandmothers in the 1960s or 1860s. The 21st century Brussels sprouts craze owes a little something to a recent bittersweet Brussels sprout metamorphosis. 

For most of the 20th century, yield optimization was front of mind for commercial Brussels sprouts growers and taste was at the bottom of the priority totem pole. Output, color, yield, and season length trumped flavor. After plant scientists discovered that Brussels sprouts have the highest level of total glucosinolates among all Brassicas—i.e. the cabbage family—developing Brussels sprouts for taste rose as a priority. Would it be possible to grow a more palatable vegetable? Inspired by the new findings, a group of seed researchers in 1990 decided to focus their efforts on flavor optimization and began testing seeds that would yield Brussels sprouts with lower levels of bitter glucosinolates. 

finding a seed in a haystack

As the 20th century came to a close and after years of pain-staking plant breeding efforts and glucosinolate testing on hundreds of experimental varieties—though nothing like Burbank’s plum hybridizing experiments—Dutch scientists found seeds that grew into sweeter Brussels sprouts with fewer sinigrins and progoitrins, the two main bitter glucosinolates in these compact cabbages. European seed companies introduced revamped commercial Brussels sprouts to the market and hoped to find an audience with an appetite for their new creation.

In the early 2000s, the farmers and chefs that grew and served milder varieties faced the tough task of converting a skeptical audience scarred by one too many bitter or mushy Brussels sprouts. But fewer sinigrins and progoitrins in these new varieties liberated chefs from worrying about bitterness and gave them the opportunity to experiment with a friendlier vegetable. In no time, mild and crispy Brussels sprouts served at restaurants converted foes and skeptics to friends and fans with relative ease. Now, even kids constantly order Brussels sprouts or ask their parents to make them Mark Bittman’s super popular roasted Brussels sprouts with garlic.

shifting our blame

It’s easy to understand why Brussels sprouts have been consistently voted the most hated vegetable for so long. But it seems unfair to blame the vegetable. Isn’t it the method that ruined Brussels sprouts? Wouldn’t it be fairer to blame those long boils instead? A daring, yet simple change in how we cook this vegetable improved our fraught relationship with Brussels sprouts. The sweeter varieties developed by scientists helped for sure, but I bet the older, bitter Brussels sprouts would still taste way better roasted than boiled.

As we enter a new Brussels sprout era, the current generation of Brussels sprouts lovers is poised to carry on a new edible legacy that their grandchildren and their future children are more likely to enjoy and carry on. As it turns out, not all edible legacies are created equal. Our grandmothers and their grandmothers meant well with their boiled Brussels sprouts, but the odds are now stacked against this legacy surviving. No offense, grandmas, but the new method to the Brussels sprouts madness is shaping up to last as a legacy our grandchildren and their grandchildren will carry on with gusto. 

Thank you for nerding out with me, and a special thanks to paid subscribers for your support! If this email was forwarded to you and you'd like to sign up for the newsletter, click the button below:

Andrea Castillo is a food nerd who always wants to know the what’s, how’s, when’s, and why’s of the food she eats.