Mats of sargassum seaweed are a treasure trove of surprises. A natural habitat for small marine life, sargassum offers food and shelter to shrimp, molluscs, crustaceans and juvenile turtles. The floating mesh entraps mostly anything along its path: lionfish eggs, trash, plastics, fuel patches.
So those brave enough to eat sargassum will want to give the seaweed a very thorough wash before digging in.
That’s the first tip from Cayman’s pioneering Chef Thomas Tennant, owner of Tomfoodery Kitchen.
“Washing it at least once and soaking it in fresh water for 10 minutes is advised, just because ocean water not only carries bacteria that are floating in it but also, it could be carrying other things in the area,” Tennant says.
The hidden risks of consuming this invasive seaweed – from rubbish to heavy metals – hasn’t stopped Tennant from experimenting with sargassum as an ingredient.
He’s already integrated the brown algae into his line of Fiyah hot sauces, using sargassum as an ingredient, alongside local Scotch bonnet peppers, in his Black Fiyah Sriracha. The result is garlicky and tangy with a bit of heat.
On a Wednesday afternoon at Camana Bay’s Bon Vivant kitchen, Tennant tested the versatility of sargassum cooking for the Cayman Compass. Fermented, boiled, baked or fried, it turns out there are many ways to incorporate sargassum into a snapper rundown.
“Because it’s seaweed, it does contain some properties that exist with other seaweed, so some more umami flavours,” Tennant says.
“It will bring out more of a savoury flavour even though it doesn’t really have a strong flavour.”
For the experimental seaweed rundown, Tennant fished his sargassum batch that morning off the shore of South Sound.
“It’s not hard to find,” he jokes.
The once seasonal seaweed has now become more ubiquitous throughout the year, so tracking down a sample is relatively easy.
Tennant adds a simple advisory: “If it doesn’t look edible, don’t do it.”
Sargassum for cooking should be fresh and have an ocean – rather than rotting egg – smell to it.
After washing and soaking it, Tennant stuffs a small red snapper with a handful of the plant, alongside lemon rounds and coconut oil – the first step in his rundown.
He adds another twist, slathering on his spicy starfruit-sargassum kimchi.
While the snapper roasts in the oven, he plucks sargassum leaves from the stem. Although the stems are edible, he compares the texture to rosemary stalks – not exactly ideal for chewing.
The leaves are chopped and sautéed with onion and garlic as a base for the rice.
For the sauce, the leaves add a savoury kick to the rundown medley of coconut milk, peppers, thyme and garlic. For spice, he chops a Scotch bonnet pepper.
Those with less heat tolerance than Tennant can cut down on the punch by throwing the pepper in whole rather than chopped.
For a crispy garnish, he fries the remaining leaves in coconut oil and dries them on paper towels. The crunchy, buttery morsels add the final touch to Tennant’s creation.
“I’m just kind of exploring,” he says.
“I know it’s not going to be something mainstream with people eating sargassum for everything.”
So, you can eat it. But should you?
While sargassum may not appear in the produce aisle anytime soon, sargassum consumption isn’t new. In traditional Chinese medicine, sargassum has been used to reduce phlegm, suppress coughs and treat thyroid problems.
A study by Southern Cross University in 2012 tested its potential for thyroid treatment. The team concluded that bioactive compounds in sargassum “could be useful in the treatment of thyroid related diseases such as Hashimoto’s thyroiditis” and recommended further research.
Another study this year by Beijing University of Chinese Medicine tested a blend of seaweeds – Sargassum pallidum, Sargassum fusiforme and Glycyrrhiza uralensis – to treat thyroid problems in rats. The study found that its seaweed tea had an effect on enlarged thyroid glands, but it came with a caveat: “The detailed underlying mechanisms remain unclear, and further studies are required to elucidate the material basis and potential side effects.”
Sargassum fusiforme, known commonly as hijiki, has been part of Japanese cuisine for centuries.
While hijiki contains dietary fibres, iron, calcium and magnesium, it is also high in another component: arsenic. Public health bodies such as the United Kingdom’s Food Standards Agency recommend against hijiki consumption.
Before boiling a steaming pot of sargassum tea or digging into a seaweed salad, culinary adventurers should proceed with caution.
In July, researcher Rosa Elisa Rodríguez Martínez of the National Autonomous University of Mexico [UNAM] warned of “serious levels” of arsenic and heavy metals such as cadmium detected in sargassum samples taken from beaches in Puerto Morelos and Playa del Carmen.
Rodríguez told Mexico Daily News that testing conducted at UNAM and the Ecology Research Center in Miami, Florida, revealed heavy metal levels as high as 120 parts per million.
She recommended holding off on eating sargassum until further studies could verify its safety.
Sargassum also carries high levels of iodine, so individuals with iodine sensitivity should abstain.