SUGAR KELP BROWN ALGAE
Sugar kelp (Saccharina latissima) — also known as sea belt or sugarwrack, and formerly classified as Laminaria saccharina — is the most useful kelp in a British kitchen. It's the closest thing our coast has to Japanese kombu, and it does the same job: building savoury depth into stocks, broths and slow-cooked dishes.
Buying and Storing
Sugar kelp is sold dried, as whole blades or cut pieces. Good dried kelp is dark olive-brown and often carries a white powdery bloom on the surface — that's mannitol, a natural sugar, and it's a sign of proper drying. Don't wash it off; it's where the sweetness lives.
Store sealed and dry, away from light. It keeps indefinitely.
Making Stock
This is the main use, and it's worth doing properly.
Put a 10cm strip of dried kelp into a litre of cold water and leave it to steep — 30 minutes if you're in a hurry, several hours or overnight in the fridge if you're not. Then bring it slowly towards a simmer and remove the kelp just before the water boils.
Boiling kelp is the one mistake that matters. It turns the stock bitter and slightly slimy, and there's no recovering it. Cold steeping gives you a cleaner, sweeter result than heat ever will.
The spent kelp isn't waste — slice it and add it back to the finished soup, or simmer it with soy and mirin.
Other Ways to Use It
- With pulses and grains — a strip added to lentils, beans, chickpeas or rice as they cook. It seasons the pot and softens into the dish.
- Under roasting — laid in the tray beneath fish or vegetables, where it perfumes as it heats.
- Braises and stews — dropped in early for body in long-cooked dishes.
- Ground as seasoning — dried and blitzed to a powder, used like a savoury salt over chips, eggs or popcorn.
- Pickled — rehydrated and sliced into ribbons, in a light vinegar pickle.
Why It Tastes the Way It Does
Sugar kelp is high in free glutamate, the compound behind umami. That's why a strip of it makes a broth taste finished rather than merely salty, and why the kelp family underpins stock traditions across Japan, Korea and China.
The sweetness comes from mannitol, which is also what makes sugar kelp gentler and more approachable than the stronger kelps like oar weed.
Common Mistakes
Boiling it. The big one. Out before it boils, every time.
Washing off the white bloom. That's flavour, not mould.
Using too much. One strip per litre is plenty. Kelp stock should sit under a dish, not on top of it.
Salting before tasting. Kelp brings its own salinity — season at the end.
A Note on Iodine
Sugar kelp is high in iodine, and levels vary considerably with season and growing conditions. Using a strip in stock and removing it transfers relatively little; eating dried kelp regularly, or taking kelp supplements, is a different matter and can affect thyroid function.
Anyone pregnant, breastfeeding, or with a thyroid condition should take medical advice before using kelp regularly.
Where It Comes From
Sugar kelp grows on rock at and below the low-tide line around Britain, Ireland and across the North Atlantic. It's also the main species farmed in Scottish and Irish seaweed aquaculture, grown on suspended lines and harvested in spring — a crop that needs no feed, fertiliser or fresh water.
Related
For identification, naming and the science, see our page on Laminaria saccharina. For other seaweeds worth cooking with, see how to cook alaria and dulse, or our guide to edible seaweed in the UK and the full guide to edible seaweed.
Seaweed has been a source of savoury flavour for centuries. Sozyë's sauces are brewed from a blend of wild Scottish seaweeds, harvested off the north coast of Scotland.