Physical properties of buckwheat durante a secagem convectiva

Buckwheat is a prominent crop in present-day agriculture due to its nutraceutical properties; however, information on this crop regarding the post-harvest process is scarce, as well as the characterization of its physical properties andsuch information is essential for the development and improvement of machinery used in post-harvest processes. Thus, the objective of this study was to determine the volumetric shrinkage, porosity, bulk density and true density of buckwheat grains throughout the drying process, as well as to fit mathematical models to the experimental values of true and bulk volumetric shrinkages. Buckwheat grains of the cultivar IPR 91--Baili with an initial moisture content of 0.250 (decimal, dry basis.) were used. The samples used to determine the physical properties were subjected to oven drying with forced air circulation stabilized at 40 [+ or -] 1[degrees]C. The mass of the samples was periodically weighed, so that when the product reached predetermined values of moisture content, the samples were removed and their physical properties were determined. It is concluded that the reduction in moisture content during drying causes increase in bulk density, true density and porosity. The reduction of the moisture content influences bulk volumetric shrinkage and true volumetric shrinkage of the grains, causing reductions in their values of approximately 14.47 and 14.70%, respectively, and a linear model can represent both variables satisfactorily.Key words:post-harvestmoisture contentvolumetric shrinkageO trigo mourisco e uma cultura de destaque na agricultura atual devido as suas propriedades nutraceuticas; no entanto, informacoes dessa cultura referente ao processo pos-colheita sao escassas, assim como a caracterizacao de suas propriedades fisicas, sendo que tais informacoes sao essenciais para o desenvolvimento e aperfeicoamento de maquinarios utilizados nos processos pos-colheita. Deste modo, objetivou-se com o presente trabalho determinar a contracao volumetrica, a porosidade, as massas especificas aparente e unitaria dos graos de trigo mourisco ao longo do processo de secagem, bem como ajustar modelos matematicos aos valores experimentais da contracao unitaria e da massa. Foram utilizados graos de trigo mourisco da cultivar IPR 91--Baili, com teor de agua inicial de 0,250 (decimal, base seca). As amostras utilizadas para determinacao das Sriedades fisicas foram submetidas a secagem em estufa com circulacao forcada de ar ilizada a tempe