Cultured earthworms as human food

In a television reality show, a man was shown eating a lot of live earthworms with gusto. This was repulsive to many viewers. Are earthworms really edible? Are they safe to eat?

Earthworms are terrestrial invertebrates that have been used as human food for ages. They are in fact considered a delicacy by the natives of Africa, South America, Japan, China, Papua New Guinea, and New Zealand.

Today, you will still find canned earthworms and dishes of mushrooms and bread with earthworms consumed in Western Europe. Restaurants in the Chinese provinces of Guandong and Fujian serve earthworm soup as a traditional food and mix earthworms with meat to make it tastier, respectively.

How nutritious are earthworms as food?

Studies have shown that the protein content of earthworm meal (processed worm biomass) is 54.6 percent higher than that of eggs or soybean. Worm meal is also rich in vitamins, particularly thiamine and riboflavine. In terms of minerals, its iron content and copper, manganese, and zinc contents are l0 times and six times higher, respectively, than those of fish and soybean.

The body fluids and tissues of earthworms contain bioactive compounds such as enzymes (e.g., fibrinolytic, lumbrokinase and collagenase). Pharmacologically active substances like triglycerides, squalene and free fatty acids (omega-6 EPA) have also been identified in earthworms in addition to endorphin, encephalin, a hypoglycemic factor and monoamines. With such health-giving benefits, the worms can be a functional food like fish, milk and soybean.

To be acceptable as human food, earthworms have to be cultured under strict sanitary and biosafety conditions. The earthworm recommended for production in the tropics is the West African nightcrawler (Eudrilus eugeniae) for being a composting species (can live without soil), prolific breeder and fast grower.

In the culture of E. eugeniae for human food, the use of soil and animal wastes should be avoided to ensure non-contamination of the product with pathogenic microorganisms and heavy metals. Commercial farming of the species in the Philippines has been achieved using grass and kakawate (Gliricidia sepium) leaves as substrates. The mass culture of earthworms is economically feasible with the production cost of Pl0-l5 per kilogram.

In preparing the earthworms for human food, they should be washed in clean running water to remove foreign materials on their body surface and then depurated to devoid their gut content by placing them in a container with moist tissue paper for at least l2 hours. The worms are blanched in 60 degrees Celsius water to kill them.

Earthworms cooked as "meatballs" were found to be as acceptable as pork meat cooked in the same way by l0 members of a taste panel in a thesis conducted at a local university. The recipe for "Surprise Worm Poplette" is: Ingredients – one and a half cups of ground earthworms, one-fourth cup of bread crumbs soaked in water, two eggs, two pieces of minced garlic, one tablespoon of kinchay, one-half teaspoon of salt and one-fourth teaspoon of pepper. Procedure – mix bread crumbs thoroughly with the ground earthworms; add the beaten eggs to the mixture; add the grated cheese, garlic, kinchay, salt and pepper; shape the mixture into small balls rolled in flour; and fry in hot oil for about l0 minutes or until golden brown.

Bon appetit!

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Dr. Rafael D. Guerrero III is the executive director of the Philippine Council for Aquatic and Marine Research and Development of the Department of Science and Technology. Among his current research interests are the development of innovative earthworm-based technologies in collaboration with colleagues at the Ohio State University and with the support of the United States Department of Agriculture-Foreign Agricultural Service. He may be reached via e-mail at pcamrd@laguna.net.