Efeitos cumulativos da secagem e da intermitência na qualidade física e físico-química do arroz em casca e integral

Abstract

Considering that the knowledge of the effects of intermittent drying on the physical and physicochemical properties of rice grains is useful for the proper management of the drying operation, increasing quality to the final product, the objective of the present work was evaluate the time cumulative effects on drying and intermittence on the physical quality of rough rice and on the physical and physicochemical quality of the brown rice processing. The rice drying was carried out in an intermittent dryer in a grain processing unit at the farm scale, with sample collection each one hour in the drying and intermittency stages. Rough rice was evaluated by physiological quality and the brown rice by the following variables: industrial quality of processing, physical classification, near infrared spectroscopy (NIR), X-ray diffraction (XRD), scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) and multivariate statistical analysis. The results obtained allow us to affirm that the drying process influenced the occurrence of changes in the quality of rough and brown rice grains. Samples with water content above 17% (w.b) in the first hours of drying decrease physiological quality of rough rice, expressed by germination and vigor tests. The final drying time resulted in decreased income and undamaged grain yield and increased broken grains and rice husks during brown rice processing. Likewise, the drying time increased the occurrence of defects as chalky, green and red grains as well impurity content. Through the analysis of near infrared spectroscopy (NIR) was verified a reduction in chemical components like proteins, fat and ash over the drying time. The greatest deformation of grains with pericarp rupture was observed at the end of drying, with an increase in relative crystallinity. The intermittency stage was the step that showed fewer changes in the physical and physicochemical grains quality.