Improving fresh pistachio quality by postharvest application of edible coating during cold storage

Fresh pistachio fruits of ‘Ahmad Aghaei’ variety were sprayed with 1% calcium oxide (CaO), 10 mM w/v γ-aminobutyric acid (GABA), 1% carboxymethyl cellulose (CMC), and their combination (CMC+GABA+CaO) for 30 s at room temperature. Spraying with distilled water was considered as the control. Following the drying of fruits at room temperature, they were packed in perforated polyethylene terephthalate and kept under cold storage (at 2 ± 1 ˚C with 85 ± 2% RH) for 75 d. The result showed that the fruit coated with CMC+GABA+CaO, CaO, and GABA exhibited the highest lightness index of the pistachio hulls compared to the control. The highest hue index of the hulls and carotenoids was observed in the fruits coated with CMC+GABA+CaO. The flavonoids in the fruits treated with CaO, GABA, and CMC were significantly higher than in other coatings. At the end of the cold storage, the fruits covered with CMC resulted in considerably higher lipid content than other coatings and the control. Pistachios treated with CMC+GABA+CaO showed lower H2O2 in hulls and kernels and the highest kernel carotenoid, and color indices than the control. In conclusion, the fruits coated with edible layers, especially with CMC+GABA+CaO, can be stored at 2±1 oC around 50 days to preserve the important traits of the pistachios.