Worms, a diverse group of invertebrates, are gaining increasing attention as a potential protein source. Their ability to offer a sustainable and efficient alternative to traditional protein sources makes understanding their protein content relevant for future food systems and animal nutrition.
Protein Content Across Worm Species
The protein content in worms can vary significantly depending on the species, and it is typically measured on a dry weight basis to account for moisture differences. Dried mealworms (Tenebrio molitor) contain approximately 45.8% to 60% crude protein. Live mealworms, with their higher moisture content, generally contain about 18% to 20% protein.
Earthworms, such as Eisenia fetida (often called red wigglers), provide substantial protein, ranging from 41.42% to 78% on a dry matter basis. Silkworm pupae (Bombyx mori) are another notable source, with dried pupae reported to have a protein content as high as 49% to 55.6%. Black soldier fly larvae (BSFL), Hermetia illucens, are known for their high protein levels, typically ranging from 32% to 63% of dry matter.
Factors Influencing Worm Protein Levels
Several variables contribute to the differences observed in the protein content of worms. The species of worm is a primary factor, as each type has an inherent biological composition that dictates its typical nutritional profile.
The diet, or substrate, on which worms are reared profoundly impacts their nutritional makeup, including protein levels. Worms fed protein-rich diets can exhibit higher protein content.
The life stage of the worm also plays a role; protein content can change as larvae transition through different developmental phases. Environmental conditions, such as temperature and humidity, influence the worms’ metabolism and growth, which in turn can affect their final protein composition.
Worm Protein in a Broader Nutritional Context
Worm protein stands out when compared to more conventional protein sources, not only in quantity but also in quality. Many worm species offer a high protein concentration on a dry weight basis, often comparable to or exceeding that of traditional meats.
For example, the protein content of dried mealworms (50-60%) and black soldier fly larvae (32-63%) is generally higher than that of beef or chicken, which typically contain 20% to 30% crude protein per 100 grams. Earthworms, with protein levels up to 78% dry mass, can also surpass the protein percentages found in beef, pork, or eggs.
Beyond quantity, worm protein is considered a complete protein source because it contains all essential amino acids required by humans. Silkworm pupae, for instance, are noted for their high content of essential amino acids, meeting the recommendations of the FAO/WHO.
Practical Applications of Worm Protein
The high protein content and favorable nutritional profiles of worms have led to their increasing use in various practical applications. A significant area is their role in animal feed, particularly in aquaculture, poultry, and pet food industries.
Black soldier fly larvae and mealworms are industrially farmed to convert organic waste into high-quality protein for animal consumption, offering an alternative to conventional feed ingredients like fishmeal and soybean meal.
Beyond animal feed, there is growing interest in entomophagy, the practice of human consumption of insects and worms. Worms offer sustainability advantages over traditional livestock farming. They generally require less land, water, and feed to produce the same amount of protein, and their farming can result in reduced greenhouse gas emissions.