Saccharina latissima or Royal Kombu is a large brown variety of seaweed of the kelp family that can reach 3 to 4 m long and 30 cm wide. Either grown wild or cultivated, it can be harvested throughout the year along the coast of Brittany with a preference for springtime when its quality is superior. Like many types of seaweed, Saccharina latissima is rich in fibre, minerals and vitamins. Due to its very high iodine content, it should be blanched with water before being ingested.
Kombu seaweed (which means “happiness” in Japanese) is one of the mainstays in Japanese cuisine. Indeed, it represents one of the main ingredients in dashi broths, the true markers of Japanese cuisine. Its high content in glutamic acid enhances the sense of roundness and fullness in the mouth. However, in its raw state, Kombu from the coast of Brittany (Saccharina latissima) is slightly less rich in glutamic acid than its Japanese cousin (Saccharina japonica). This is undoubtedly related to the difference in species, but also to the drying technique (in Japan they are dried naturally in the sun, allowing the seaweed to “mature” and partially hydrolyse the proteins).
Besides its subtle umami flavour, it has a strong taste of iodine, and is slightly smoky and sweet. Rather than adding new flavour, it essentially enhances the flavour of the other ingredients present in the formulation. Its’ fairly hard raw texture becomes crunchy after blanching and even tender when cooked in water, in the same manner as a commonly eaten vegetable. It is preferentially cooked in water or in broth because it requires a sufficient supply of liquid to soften its texture. Indeed, cooking in fat tends to dry it out and plasticize the texture.
During a culinary exploration of Kombu, different behaviours and functionalities have been identified according to the techniques used, to the way of cooking and to the combination of ingredients.
The cooking time for rehydrated dried kombu results in different textures:
• 5 to 10 minutes: very crunchy
• 10 to 20 minutes: crunchy
• 20 to 30 minutes: soft
• Between 30min and 1h: very soft
Cooking times should therefore be adapted according to the intended culinary use.
While still crunchy, kombu can be cut into cubes to compose salads, garnish wraps or sandwiches and even incorporated into healthy and gourmet bowls. Kombu salad with sesame dressing is a particularly harmonious combination. However, its association with fresh tomatoes should be avoided. Blending kombu with delicate hints of sweetness is pleasant and brings out the seaweed’s iodine notes. Thus, adding cranberries or raisins to a complete salad including starch, vegetables and / or acidic fruit and kombu would make an ideal composition.
If softened, kombu can be stir-fried with other vegetables for a vegetarian recipe or incorporated into a quiche, pie, or cake similarly to other land vegetables compositions such as onion chutney, leeks, mushrooms, etc.
After a long cooking time and if the seaweed is mixed, the texture becomes slightly jellified and helps to bind certain preparations like sauces, soups, cream soups, spreads, or purees …
It is noteworthy that when mixed raw or merely blanched, its gluiness is more prevalent. This character is particularly intense when kombu is in contact with dairy cream, since the compounds in these two ingredients seem to interact strongly.
Another noteworthy fact that has been verified is that the presence of kombu in the cooking water of legumes significantly reduces their cooking time (by approximately one third). This fact was acknowledged and tested during the present project; however, it has been scarcely explained in the literature … Many publications mention additional concepts, which are undoubtedly interesting, but that do not refer to scientific observations and explanations. These include the emollient nature of glutamic acid which allows for leguminous fibres to “break up”, thus improving the digestibility of the legumes (less flatulence, etc.), increasing the availability of proteins and increasing the nutritional value. These subjects are yet to be better understood in order to better valorise them!
Knowing these are only hypotheses, results from this project point out how the alginate contained in kombu, by dissolving during cooking, could chelate the calcium in the water and in turn lead the cell walls of legumes to become more tender (cell walls are generally rigidified by calcium). The significant richness of Kombu in potassium (10% in Japanese kombu on average) is also a key element that can explain exchanges with calcium.
To conclude, kombu is a seaweed that doesn’t have a very strong taste, but it carries the umami flavour, it is easy to cook, it can be easily incorporated into different culinary preparations and provides meals with a delicate and enveloping flavour.
Finally, for the record, in Japan, dried kombu is also brewed alone or with Japanese green tea to improve digestion. This is called Japanese KOBUCHA, not to be confused with the western fermented drink KOMBUCHA which is very popular nowadays!