Drying kinetics of Amaranthus cruentus ‘BRS Alegria’ seeds in natural and artificial methods

Abstract

The seeds of most crops are often harvested with water concentrations above the recommended levels; for instance, amaranth crops can be harvested under water contents up to 40%. Therefore, drying of the harvest is essential to preserve its post-harvest quality. Thus, the objective of this study was to investigate the drying kinetics of Amaranthus cruentus ‘BRS Alegria’ seeds dried via natural and artificial methods. Drying experiments were conducted in laboratory under natural methods, in shaded and open sun conditions, and also under artificial drying at temperatures of 60, 80 and 100 °C. The average temperatures of the seed mass were 30, 40, 50, 60, and 70 °C for the natural drying methods, shaded and open sun, and under the artificial drying at temperatures of 60, 80, and 100 °C. The modified Midilli equation proved to be the best model for describing the drying kinetics of Amaranthus cruentus ‘BRS Alegria’ seeds. For the artificial drying method at temperatures of 60, 80, and 100 °C, durations of 2.5, 3.5, and 7 hours were respectively required to reduce the water content from 21.1% to 11.5%; and, 4.25, 4.75, and 10 hours to reduce concentration 21.1% to 8.5%. For natural drying under open sun, a drying time of 15 hours was required; for shaded conditions, a drying time of 164 hours was required until the water concentration reduced to 13% which was the equilibrium moisture.