effect of storage temperature on mechanical properties of pistachio kernels

after harvesting, pistachio nuts are generally kept in storage before being exported. during handling, thenuts are exposed to external forces that cause mechanical damage to them. the increase of the mechanicaldamage is a function of storage conditions, especially temperature. this research investigated the effect ofstorage temperature (25, 5, -5, -15°c), on the mechanical properties of pistachio kernels. the kernels werekept at the four storage temperatures for three months. durability, impact, compression and comminutiontests were then performed on the kernels. the statistical analysis of the data indicated that the negativetemperatures had lower durability damage, but caused the kernels to become brittle, which increasedimpact damage. in the compression test, the modulus of elasticity of the kernels at 25, 5, -5, -15°c were64.17, 63.11, 37.70 and 26.56 mpa, respectively. this also indicated that the power required to causebiological yield in the kernels increased as storage temperature increased. the comminution test showedlittle difference in the distribution of broken kernels on different sieves.