Evaluación de alternativas de secado en el proceso de elaboración de harina de lombriz

Abstract

Production of earthworm flour includes several steps, among which the most critical is the drying process due to factors such as time and energy requirements. In addition, the information available about this process is relquite limited. Thus, this work evaluated four drying techniques likely to be implemented by lombricultores: sun drying, oven drying, drying tunnel and microwave assisted drying. Drying kinetics values were obtained for all drying techniques, and specific parameters as the following were evaluated: drying tray material (stainless and ceramic steel) for sun drying, microwave power (30%, 50% and 80%) and amount of material to be dried (72 and 100 g) for microwave assisted drying, temperature (50, 65, 90 and 100 °C) for oven drying, and temperature (50 and 63 °C) and air speed (2.9 to 3.6 m/s) for tunnel drying. It was determined that the most efficient technique is the drying tunnel, because this allows the combination of heat transfer by conduction and convection, and enables controlling the operating parameters. Finally, nutritional analyzes were performed in samples obtained by each drying technique evaluated. The crude protein content for sun drying, microwave assisted drying, oven drying and tunnel drying were 66.36 %, 67.91 %, 60.35 % and 62.33 % respectively, indicating that the drying method and operating parameters do not significandy affect the crude protein content.