Different drying methods of Pistacia Atlantica seeds: Impact on drying kinetics and selected quality properties

Abstract

The effect of different drying procedures on the quality characteristics of Pistacia atlantica subsp. kurdica is addressed in this work. Using five different drying methods include microwave, oven (40 and 60°C), sun, and shade, P. atlantica were dried. The variations in moisture content, drying rate, major components of essential oil, and texture property were assessed at the start and at the end points of the drying process. Comparison of the drying methods indicated that microwave drying to be most effective in lowering moisture content, while the shade drying had the lowest rate among methods. In the case of microwave, the dried seeds had highest brittleness, while the highest score for the penetration force was observed in oven 40°C. Regarding major elements of the essential oil (α-pinene, α-terpinen-4-ol, myrcene, β-ocimene, β-caryophyllene, and limonene), there were no significant differences between the five drying techniques, nor compared to the fresh sample. To model the drying process, six thin-layer drying kinetic models were chosen. It was found that the Midilli–Kucuk model was the most suitable for explaining the drying curve of oven 40 and 60°C, microwave, and sun methods; Wang and Singh model was excellent to explain thin-layer shade drying behavior of the P. atlantica seeds. In conclusion, in this study, an opportunity is represented to apply the most effective procedures to decrease the drying period and to achieve a product with appropriate safety and quality features.