Kombu: The foundation of Umami
It all started with a bowl of kombu dashi. In 1908, Dr. Kikunae Ikeda tasted something he couldn’t name. It was a satisfying depth beyond sweet, salty, sour, or bitter. He identified that fifth taste as umami — and changed the way we understand flavor forever. Kombu is the reason why we have umami. And it’s become a quiet, yet powerful umami-rich ingredient to build on for professional chefs around the world.
Although traditionally, kombu has been used as a backbone of Japanese dashi, it’s become a staple for Michelin chefs worldwide. Rich in natural glutamic acid, it can be used to infuse stocks, cure proteins, and layer complexity into sauces, oils, and beyond.
Let’s learn more about where this authentic Japanese kombu comes from, how it’s made, why it’s at risk and what we can do to support.
Where does authentic Japanese Kombu come from?
If there’s one thing that defines authentic kombu, it’s the ocean. Over 95% of kombu is harvested in Hokkaido, the northernmost region of Japan where the cold waters from the Oyashio Current flows down from the arctic. This current is packed with nutrients like nitrogen, phosphorous and silicon creating ideal growing conditions for kombu. On the flip side, the Tsushima Current along the Sea of Japan brings warmer, nutrient-poor waters, unsuitable for kombu cultivation.
What’s even more interesting is how these currents shape the coastlines differently. Some areas get more exposure to open sea, others are more protected. That subtle variation in temperature, salinity, and nutrient flow means the kombu that grows there develops its own unique character.
It’s why different regions are known for different types of kombu. Ready to dig in to the kombu varieties?
3 Types of Kombu: Where it’s from, what it tastes like and how to use it
Just like wine grapes and single-origin coffee beans, kombu reflects the character of the water it grows in. Its environment influences its texture, flavor, and how it performs in the kitchen. That’s why top chefs don’t just ask for kombu. They ask for specific varieties of kombu.
Here’s a quick breakdown of three foundational kombu types, where they come from, what they taste like, and how to use them in your kitchen.
1. Rishiri Kombu
- Sourced from: Rishiri, Rebun, and Wakkanai (Northern Hokkaido)
- Flavor: Savory, aromatic
- Dashi Color: Clear, golden
- Ideal for: Dishes that require a deep umami base
- Think: Kaiseki-style clear soup, kombu-infused beurre blanc, kombu-cured hamachi crudo
2. Rausu Kombu
- Sourced from: Shiretoko Peninsula (Eastern Hokkaido)
- Flavor: Robust, slightly sweet
- Dashi Color: Dark amber-hued
- Ideal for: Full-bodied, umami-forward dishes
- Think: Kombu-based corn velouté, kombu-infused red wine jus, risotto with kombu stock
3. Hidaka Kombu
- Sourced from: Hidaka region (Southern Hokkaido)
- Flavor: Soft, mellow, nuanced
- Dashi Color: Pale golden
- Ideal for: Simmered dishes and edible preparations
- Think: Kombu-braised short ribs, kombu confit, kombu-wrapped cheese tempura
If you’re wondering “Where’s Ma Kombu?”, rest assured we will be writing a whole separate blog post on Ma Kombu. Stay tuned.
Now, that you’ve learned about the basic types of kombu, now let’s get into the craft of kombu.
How is Kombu made? The process of crafting umami-rich Kombu
Behind every sheet of kombu there’s an artisan and their craft. After harvest, the kombu is gently washed to remove any sand or debris, then laid out under the sun. This is a traditional method called Tenpiboshi. Sun-drying doesn’t just preserve the kombu, it actually deepens its umami flavor by concentrating glutamic acid through natural enzymatic reactions.
Some producers take it a step further by aging kombu in temperature and humidity-controlled cellars called Kura. The flavor becomes rounder, more complex, and the briny ocean aroma fades over the months and sometime years of aging. Similar to how cheese and cured meats develop character over time. At The House of Umami, our Rishiri Kombu is aged for 1-3years in a traditional kombu cellar in Fukui Prefecture.
Some kombu is transformed into shaved kombu. Oboro Kombu is made by soaking the kombu in vinegar and shaving it into extremely thin, translucent strips. This hand-shaving process can only be done by traditional kombu shaving artisans — only a handful are left. Battera Kombu, one of our most popular products, is the final layer left behind after shaving — therefore limited in quantity compared to regular kombu. It’s used to wrap traditional pressed sushi in Japan, but many chefs around the world are seeking out this rare Japanese kombu.
Kombu Sustainability: Why Kombu harvests are declining
Kombu doesn’t just grow — it depends on a delicate marine ecosystem. Plankton feed the kombu, and kombu in turn becomes a food source of sea urchins. When that balance tips, everything shifts.
Rising sea temperatures, changing currents, increased grazing by sea urchins and fish are throwing this system off. In some coastal regions of Japan, a phenomenon called iso-yake is turning once-rich kombu beds into underwater deserts.
Add to that a human factor — the aging farmers. Many of the kombu farmers today are in their 60s or 70s, with few young successors willing to take on the labor-intensive work. So even as demand grows, the supply is becoming more fragile — both from nature and from the loss of traditional knowledge. For chefs who rely on these authentic Japanese ingredients, understanding where kombu comes from and what threatens it is becoming just as important as knowing how to use it.
Here’s what you can do to support small Kombu farmers
At The House of Umami, we source rare Japanese ingredients directly from the small producers who have been quietly shaping Japan’s culinary heritage for generations. By choosing our kombu, you’re not only bringing depth and authenticity to your dishes — you’re helping sustain the aging kombu farmers and regional traditions behind it. Every purchase helps preserve the craft, the coastline, and the culture that gave rise to umami itself. Check out our kombu collection here.