Engineering characterization of Persian walnut and its kernel (Juglans regia L.) for obtaining high quality produce

Knowledge of walnut fruits properties as a function of moisture content is crucial for the efficient processing of the product and optimizing oil extraction. Several engineering properties such as average geometric diameter, unit mass, surface area, volume and sphericity were evaluated in Persian walnut and its kernel. All the parameters increased as the moisture content increased from 3.41 to 17.65% dry basis. For the bulk density, true density, porosity and repose angle of nuts, the moisture dependent changing ranges were 315.51-300.12 kg/m3, 688.05- 664.83 kg/m3, 54.11-54.85%, 38.05-39.1°, respectively, while the corresponding values for kernels were 377-364 kg/m3, 1,043.6-1,028.7 kg/m3, 63.87%-64.61%, and 40.6-41.5°, respectively. The static coefficients of friction range on glass, steel, galvanized iron sheet and plywood were 0.284-0.293, 0.276-0.301, 0.307-0.321 and 0.404-0.426 for nuts and 0.322-0.332, 0.312-0.323, 0.348-0.360 and 0.443-0.451 for kernels, respectively. The force required for initia...