Evaluation and Comparison Methods of Splitting Pistachio Nut and its Effect on the Quality Properties of The Product during Storage

In this study, two methods of opening the pistachio shell (ice and mechanical methods) and natural opening at two storage temperatures (10°C and 25°C) and six months storage for Ouhadi pistachio cultivar, were compared in terms of peroxide index, acid number and sensory proprties. The results showed that the rate of changes in peroxide index during six months of storage varied from 2 to 3 mEq / kg, the changes in acid rate ranged from 0.51 to 0.85 mg / g and the moisture content of the samples varied from 4.36 % to 6.23 %. The highest amount of acidity (0.85 mg / g) and peroxide index (3.1 mEq /kg) in open shell samples was observed in the ice openenig method and storage tempreture of 25° C. The lowest acidity (0.51 mg / g) and peroxide index (2 mEq / kg) was observed in mechanical method opening and storage tempreture of 10 ° C. However, with the increasing of the storage time, peroxide index and acidity were incresed but the peroxide index at the end of storage in all treatments was found lower than the recommended safe limit (5 mEq /kg). The highest percentage (92%) and rate of shell opening (6.4 mm) were obtained by mechanical method. The percentage of pistachios that were crushed by the mechanical method was 2% and 3% higher than that in other two methods, respectively. According to the panel judges, the mechanical method was more desirable than the other two treatments with 86.5% of total acceptability. According to the significant effect of the appearance and chemical properties on the acceptability of the pistachio, it was concluded that the mechanical shell opening method was more acceptable method for artificially shell opening than the other methods.