Impact of instant controlled pressure drop texturing on the drying of yellow mealworms

Abstract

Insects are increasingly being evaluated as promising protein sources for the food and feed sectors. However, to be accepted as a viable food source, insects must undergo proper processing. Drying is a crucial step in insect processing, as it inhibits the growth of harmful microorganisms, improves their stability and extends their shelf life. After drying, insects can be further processed into various forms, to make them more socially acceptable as food and feed. During drying, biological materials are prone to shrinking, which usually affects their quality. Shrinkage of dried biological material results in a compact structure and causes a significant reduction in water diffusivity. It is typically escorted with unsatisfactory organoleptic quality and problems with grinding. Therefore, including retexturing and structure-expanding techniques in regular drying procedures is becoming essential. The instant controlled pressure drop (DIC) technique was suggested as a texturing technique for yellow mealworms. DIC treatment successfully overcame shrinkage at treatment conditions of 0.194 MPa/32 s and above, resulting in enhanced water diffusivity of 1,833 and 682% for DIC-treated larvae at 0.45 MPa/25 s, dried at 50 and 60 °C, respectively, as compared to blanched larvae. Furthermore, DIC caused a 125% increase in the specific surface area of the dried meal, and a more uniform particle size distribution, both of which reflect the influence of this pretreatment on grinding and, consequently, the end product’s quality. Finally, experimental data of sorption isotherms at 20, 30, and 40 °C were fitted with Brunauer-Emmett-Teller (BET), Guggenheim-Anderson-de Boer (GAB), and Oswin models to represent the sorption behaviour.