Do you know the differences between konbu types?
Natural Konbu and Farmed KonbuNatural konbu is kelp that has been growing naturally for two years on rock reefs. Whereas, farmed konbu involves artificial cultivation of natural kelp spores, which, when big enough, are then attached to ropes (kelp lines) and cared for as they grow. Of these, the kelp harvested after one year is called “sokusei”, or “forced cultivation” and that harvested after two years is called “yoshoku”, or “farmed”.
Natural konbu attaches to rock reefs to grow there on the seabed, so it is vulnerable to damage from sea urchins that dine on it as a food source. Whereas, farmed konbu grows on horizontal ropes close to the sea surface, where sea urchins cannot reach and cause damage. Yet, plenty of sunlight reaches farmed konbu just under the waves, stimulating greater photosynthesis activity, which often makes farmed konbu look more attractive than natural konbu.
A price comparison between natural and farmed konbu shows that natural konbu is more expensive, yet, there is hardly any difference in quality, which means that farmed konbu sometimes sells for more at bidding auctions. Furthermore, compared to natural konbu, farmed konbu provides a stable annual crop, which makes it a favorite among buyers.
About GradesThe number of grades and naming formats vary depending on the type and quality of the konbu concerned, but, in general, the grades are divided into four (1st to 4th). The grade is determined by the length of a single leaf of kelp, its thickness, weight, hue and other various deciding factors.
From right to left: 1st grade (green string), 2nd grade (red string), 3rd grade (purple string), 4th grade (brown string)