Investigating Different Methods of Closed Shell Pistachios Splitting and Effects of Freezing Prior to Drying on Shell Splitting Percentage

In this study, different methods for shell splitting and the effect of freezing prior to drying on shell splitting percentage of pistachio were investigated. A completely randomized design was used to investigate the effects of different freezing temperatures (0, -6, -12 and -18°C), different drying temperatures (80, 90 and 100°C) and different cultivars (Akbari and Kalehghouchi) on shell splitting percentages. The results showed that both freezing and drying temperature significantly (p ≤ 0.05) affected  the splitting of closed shells into open shells. The effect of cultivar was insignificant. The  highest shell splitting percentage (16.56%) was observed with a freezing temperature of -18°C and when a drying temperature of 100°C was used. Freezing and drying temperatures did not significantly increase the number of isolated kernels. However, in most treatments, isolated kernels were observed. Despite the isolated kernels, The shell splitting percentage did not decrease in any of the treatment groups. The results showed that freezing prior to drying can increase the percentage of split pistachio nuts. Thus, by increasing the difference between the temperature of the freezing and the temperature of drying, the percentage of split pistachio increased.