Processing Techniques affects the Vitamin Quality of Edible Insects – Potential for Use in Complementary Foods
Virginia Wambui *
Department of Chemistry, School of Pure and Applied Sciences, Kenyatta University, Kenya.
Hudson Nyambaka
Department of Chemistry, School of Pure and Applied Sciences, Kenyatta University, Kenya.
Judith Kimiywe
Department of Foods Nutrition & Dietetics, School of Public Health & Applied Human Sciences, Kenyatta University, Kenya.
Chrysantus Tanga
TInternational Center of Insect Physiology and Ecology, Kenya.
*Author to whom correspondence should be addressed.
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.
Keywords: Termites, locusts, grasshoppers, lake flies, vitamins, degradation