Over 90% of domestic natural konbu is produced in Hokkaido.
- More than 90% of domestic natural konbu is produced in Hokkaido.
- Over 90% of the natural konbu produced domestically comes from Hokkaido.
- More than 90% of the natural konbu in Japan is produced in Hokkaido.
Over 90 percent of domestic wild konbu comes from Hokkaido.

Using specialized tools, kombu is harvested by rolling it up from the ocean floor.
- Specialized tools are used to harvest kombu by collecting it from the ocean floor.
- Using specialized tools, kombu is harvested from the ocean floor.
- Kombu is harvested from the ocean floor using specialized tools.
A special tool is used to twist the kelp growing on the seabed and hoist it out of the water.

Umami components are extracted from kombu by just putting it in water and heating it.
- "Umami flavor compounds are released from kombu just by soaking it in hot water."
- "Kombu releases umami components simply by being placed in hot water."
- "By merely putting kombu in water and heating it, umami substances are extracted."
Simply soaked in water and heated, konbu releases its umami flavour components.

"When making dashi broth, it is important to avoid overheating the broth. If you overheat it, it will become bitter."
1. "When making dashi broth, it is important to avoid overheating the broth. If you overheat it, it will become bitter."
2. "It is essential to avoid overheating when preparing dashi broth, as overheating will make it bitter."
3. "When preparing dashi, be careful not to overheat it, as this will result in a bitter taste."
It’s important not to overdo the heating; otherwise bitterness will be imparted to the stock.

Kelp from Hokkaido became available in Japanese markets after the shipping route between northern Japan and Osaka was established in the 18th century.
1. "Kelp from Hokkaido started to be distributed in Japanese markets after the trade route between northern Japan and Osaka was established in the 18th century."
2. "In the 18th century, after the shipping route connecting northern Japan and Osaka was established, kelp from Hokkaido became available in markets across Japan."
3. "The circulation of Hokkaido kelp in Japanese markets began after the establishment of a transport route between northern Japan and Osaka in the 18th century."
It was in the 18th century, after a new maritime route from northern Japan to Osaka was developed, that Hokkaido konbu became commercially available around the country.