DIFUSÃO LÍQUIDA EFETIVA DURANTE A SECAGEM DE GRÃOS DE SOJA EM DIFERENTES TEMPERATURAS E TEORES DE ÁGUA

Abstract

Soybeans (Glycine max) belonging to the Fabaceae (leguminous) family represent a high production and stand out among agricultural commodities. The most used process to ensure the quality and stability of post-harvest vegetable products is drying. Therefore, the objective of this study is to determine the effective water diffusivity and activation energy in soybeans during drying at different temperatures and initial moisture contents. The grains (cultivar Intacta RR2) were harvested with initial moisture content of (0.233±0.006 dry basis, db). Thus the effective diffusion coefficient was determined from the different initial moisture contents of approximately 0.233; 0.206 and 0.193 (db). The grains with different moisture contents were submitted to drying in an oven with forced air ventilation in the four temperature conditions of 40, 60, 80 and 100 °C, in stainless steel trays of 25 cm diameter. To describe the liquid diffusion, the spherical geometric shape model with an eight-term approximation was used. The experiment was conducted in an entirely randomized design, following a 3 x 4 factorial scheme (3 moisture content x 4 drying temperatures), with three repetitions. It is concluded that the diffusivity of soybeans increases for the same drying temperature as an increment in the initial moisture content of the grains.