Evaluation of walnut kernel quality (as degree of crushing) obtained under impact loading

In this research the quality of walnut kernels under impact loading were studied. Due to unavailability of specific varieties of walnut in Iran, the tests were carried out on the available genotypes. Three different genotypes from walnut orchards of Azarshar region were selected and were collected in 2009. A drop test device was designed and constructed to perform the experiments. The impact tests were performed considering five factors in a factorial experiment using completely randomized design with five replications. The factors were genotype, moisture content, geometrical mean diameter, load direction with three levels and the hammer drop height (five levels). The effect of these factors on kernel quality was examined. Walnut cracking assessments and kernel quality were evaluated by well-defined criteria. Generally, by increasing the moisture content, the percentage of broken kernels decreased while the number of unbroken kernels increased and the quality grade of the kernels improved. The percentage of broken kernels increased as hammer drop height increased. Soaking the walnuts in water for 3 hours, with transverse loading (in Y direction) and hammer drop height of 35cm were formed the best set of walnut cracking parameters for obtaining quality kernels.