Processing Techniques affects the Vitamin Quality of Edible Insects – Potential for Use in Complementary Foods

Abstract

Aims: To assess the vitamin content of locusts, lake flies, grasshoppers, and termites when fresh, sun-dried, oven-dried, and defatted. Study Design:  Whole insect samples were sun-dried and oven-dried. Due to their high-fat content, termites and grasshoppers were subjected to an additional defatting step after the sun-drying and oven-drying. Place and Duration of Study: The study was carried out in Kenyatta University's food science lab from August to December 2020. Methodology: Prepared insect samples were ground and analyzed for vitamins using high-performance liquid chromatography (HPLC). Analysis was done in triplicates and results were expressed in mg/100g of dry insect sample. Results: Fresh insect samples had higher vitamin concentrations compared to the processed samples. For ascorbic acid, there was no significant difference between; a) sun-dried and defatted sun-dried termites (p=0.79), b) oven-dried and defatted oven-dried termites (p=0.51), c) defatted oven-dried and defatted sun-dried grasshoppers (p=0.22) and d) sun-dried, and defatted oven-dried grasshoppers (p=0.59). For thiamine, pyridoxine, riboflavin, and α-tocopherol there was a significant difference for all the samples in all the insects (p<0.0001). For niacin, fresh, sun-dried, oven-dried, and defatted oven-dried termites showed no significant difference in concentration (p=0.22). However, there was a significant difference for the other insects (p<0.0001). For beta-carotene, only oven-dried and sun-dried grasshoppers didn’t significantly differ (p=0.76). Degradation for water-soluble vitamins was highest in sun-dried samples, while fat-soluble vitamins were highest in oven-dried samples. Conclusion: Fresh insects contain vitamins that meet the recommended dietary allowance (RDA) values for children up to 36 months, except for beta-carotene. Processing significantly reduces the vitamin levels to below RDA values except for ascorbic acid, thiamine, and alpha-tocopherol in lake flies and termites, which can be used to formulate complementary foods to meet 100% of the RDA.