Effect of drying air temperature on the physical properties of macauba kernels (Acrocomia aculeata)

Abstract

The aim of this study was to evaluate the influence of moisture and drying temperature on the physical properties of macauba kernels. The experiment was set up in a split-plot design, with drying temperature (60 °C, 70 °C, 80 °C, and 90 °C) assigned to the plots and moisture (4.3%, 5.3%, 6.0%, 7.0%, and 8.9% b.u.) assigned to the subplots, in completely randomized design (CRD) with nine replications for the variables (Ci, E, Dg, Ap, S, ρu, ε, and ψ) and four replications for the variable ρa. During the drying process, the geometric diameter, sphericity, roundness, projected and surface area, apparent specific mass, and total porosity were evaluated. These variables were analyzed according to drying temperature and moisture. Reducing the misture of macauba kernels led to an increase in geometric diameter and projected and surface area and to a reduction in roundness. Increasing the drying temperature led to a reduction in geometric diameter, sphericity, roundness, and projected area and surface area. The linear model fitted well the geometric diameter, roundness, and projected area and surface area of the macauba kernels for all drying temperatures and moistures. The quadratic model fitted well the phenomena of sphericity, total porosity, and apparent specific mass and unit-specific mass. It was concluded that the physical characteristics of macauba kernels are affected by varying drying temperatures and moistures. These data can be used to size the equipment for the main post-harvest operations.