Kelp is a type of algae which has a number of uses in food, especially in Asian cuisine. It can also be processed to extract useful substances like alginate, which is used as a thickener in various commercially produced foods. Kelp can be purchased in a wide variety of forms, from fresh to dried, and it is also a component ingredient in an assortment of foods. In some cases, the focus of a dish may be on the algae, while in other instances, it is a supplemental ingredient, and consumers might not even notice it.
The term is generic for brown algae in the Laminaria genus. Kelp grows in large forests underwater that provide food and shelter to an assortment of marine organisms, and it has also traditionally been harvested by humans as a food vegetable. This algae has other uses as well; it can be burned to produce an ash used in come manufacturing industries, and it also can be used in fertilizer blends. Since kelp is rich in iodine, it is also a useful addition to the human diet.
Most commonly, kelp is harvested and dried so that it can be packaged, shipped, and stored easily. When dried, it can be used like a garnish, rehydrated and added to foods like soup and stews, or ground up with doughs for crackers and other snack foods. The popular Japanese food called nori is also made from seaweed, but the seaweed is in a different genus, so nori is not considered a kelp product. Dried kelp is also used to create soup stocks.
Fresh kelp has historically been used as a vegetable. It can be marinated to make salads, or included in mixed vegetable dishes. Various parts have different textures, from crunchy, dense stems to chewy leaves, allowing cooks to experiment with a range of mouthfeels when they use it in their food.
Dried kelp is often available in Asian markets or in health food stores, since some people like to use it as a dietary supplement. Some small regional producers make sun dried varieties that are handled without preservatives, for people who are concerned about additional ingredients in dried foods. A number of dried forms are available, from powders intended for soup stocks and spice mixtures to whole dried leaves that can be rehydrated. Dried versions should be stored in a cool, dry place, while fresh should be refrigerated and used quickly.