Nutritional and safety evaluation of locust (Caelifera) powder as a novel food material

Insects are considered edible food resources with sufficient nutrients, but their nutrient composition and safety evaluation have not been fully investigated yet. In this study, we investigated the nutrient composition and the acute and sub-chronic toxicity of locust powder in male rats. In the acute oral toxicological experiment, rats were administered locust powder at a dose of 10 or 20 g/kg/dose, followed by monitoring general signs of toxicity for 14 days. In the sub-chronic toxicological experiments, rats were fed with a diet containing 1% and 3% locust powder for 28 and 90 days. General signs of toxicity, body weight, plasma and blood components, weight and fat accumulation in tissues, and fecal fat excretion were investigated. The locust powder was rich in proteins, essential amino acids, minerals, and polyunsaturated fatty acids. In the acute toxicological experiment, no general signs of acute toxicity were observed at a dose of 20 g/kg. In the sub-chronic toxicological experiments, parameters related to red blood cell were lowered by the 3% locust powder for 28 days, but not for 90 days. Liver lipid accumulation and fecal fat excretion were increased by the 3% locust powder for 90 days, but the liver lipids contents were considered to be within a nontoxic level. Cecum contents and cecum short-chain fatty acids were lowered by the locust powder, which can be caused by its fiber and fiber-like components. In conclusion, acute and sub-chronic intake of locust powder had little effect on general, biochemical, and hematological signs of toxicity in rats. Practical Application Edible insects are increasingly viewed as new sustainable protein sources for human foods and livestock feeds worldwide because of their high nutritional balance, high food conversion rate, and environmental merits. Here, we have clarified that a locust powder contains high levels of protein, polyunsaturated functional fatty acids, and minerals (iron, zinc, and magnesium), and intake of locust powder (3% in diet) had little effects on general, biochemical, and hematological signs of toxicity in male rats. Locust as an edible insect, in powder form, can contribute to human dietary needs.