Eels – Concerns, Preparation, and Nutritional Quality

Unagi is the Japanese word for freshwater eel and was not originally part of the Edo (old name of Tokyo) style sushi menu. During the Edo period eel were abundant in the area and there were many unagi chefs. Being an unagi chef was considered a separate profession since it required great skill (much like being a sushi chef).

The Japanese eel (Anguilla japonica) is part of the family Anguillidae that includes 19 species and six subspecies. It is found in Japan, Korea, China, Taiwan, and Vietnam as well as northern Phillipines (Encylcopedia of Life; IUCN). They live in freshwater, estuaries, and coastal environments including rivers, streams, and wetlands (IUCN) where they feed and grow as yellow eels for a number of years before maturing to and becoming silver eels. Their population like the rest of the anguillid eel population worldwide, have declined drastically due to a combination of overfishing, habitat loss, and/or changing water conditions. Eel farming is responsible for over 90% of all Anguilla production worldwide but is dependent on wild-caught juvenile eels (glass eels) since breeding eels in captivity has had limited success (IUCN).

Eel is a difficult fish to prepare and is cooked when used as sushi and never eaten raw.  Eel has a sweet, but earthy aroma, and if it is prepared improperly, the flesh can smell and become tough and rubbery. The eel is first filleted and then grilled on an open flame, getting rid of excess fat under the skin, where most of the unpleasant smell comes from. The eel is then steamed to make the meat fluffy and further drain out the oils. After steaming it is once again grilled on an open flame while basting it many times with eel sauce (unagi no tare) which is made from eel trimmings, soy sauce, sugar, and sake (rice wine).  Eel should be soft, fluffy, and very flaky. It is mild in fat even after the grilling and steaming and is pleasant on the palate and should never have a fishy or earthy aftertaste (Sushi Encyclopedia).

Notable nutrients in eel are vitamins A, D, E, B1, B2, and selenium. Eel is also a good source of protein and essential fatty acids (DHA and EPA). Essential fatty acids are good for heart health and brain function. Vitamin D is important for bone health by maintaining intra- and extra-cellular phosphorus and calcium concentrations within an acceptable range, and plays a potential role in cancer prevention and immune functioning. Vitamin A is important for eye health and bone development and maintenance. Vitamin E’s principal function is the maintenance of membrane integrity, including possible physical stability, in body cells and also acts as an antioxidant. One of the clearest functions of selenium is that of an essential cofactor for the enzyme glutathionine peroxidase, which catalyzes the removal of hydrogen peroxide and hydroperoxides from tissues and is also necessary for iodine metabolism and has been suggested to regulate thyroid hormone production. The B vitamins are important in many energy metabolism pathways as coenzymes.

For Daily Power Foods

Joshua Foster, RD

References:
Encyclopedia of Life. Anguilla japonica. http://eol.org/pages/206835/overview. Accessed 24 October 2014.
IUCN. The IUCN Red List of Threatened Species: Anguilla japonica.http://www.iucnredlist.org/details/166184/0.   Acessed 24 October 2014.
Sushi Encyclopedia. Eel Sushi. http://www.sushiencyclopedia.com/sushi_menu/eel_sushi.html/. Accessed 24   October 2014.