Usefulness of physical parameters for pistachio cultivar differentiation

- Oil viscosity is correlated with the percentage of oleic and linoleic (R = 0.92).
- B* (oils) and L* (flours) are useful parameters for cultivar differentiation.
- Grouping by origin, differences were found in kernel length and oil viscosity.
- Physical parameters are useful for cultivar and cultivar origin differentiation.

Pistachio kernel characteristics are influenced by cultivar on a greater way than other tree nuts. Previous studies have focused on the analysis of chemical traits of pistachio cultivars, with little attention been paid to differences in their physical parameters. To solve this disregard, differences in the physical traits of twenty different cultivars from nine different countries are evaluated in this study. To identify the cultivar effect, all pistachio varieties were grown in the same plot to remove environmental and land management effects on kernel traits. Regarding kernel size, significant differences were found in the kernel length and width, but not in the relation length/width. Significant differences in the colour of pistachio by-products, pistachio oil and flour, were found. Colour parameter b* in oils and L* in flours allowed the differentiation of 25% and 40% of considered cultivars, respectively. The differences in the fatty acid profile of cultivars seems to affect oil viscosity, allowing the calculation of the content in oleic and linoleic acids with the viscosity data. Viscosity values ranged from 59.71 mPa s in Kerman to 63.93 mPa s in Avdat. By grouping the considered cultivars depending on their origin countries, significant differences were found in the kernel length and oil viscosity but not in the colour parameters (L*, a*, b*). This study certifies the usefulness of some physical parameters to confirm authenticity of kernels and pistachio by products depending on the cultivar and its origin.