Effect of Salicylic Acid Incorporated Chitosan Coating on Shelf Life Extension of Fresh In-Hull Pistachio Fruit

Abstract

The effect of edible coating on the postharvest quality of fresh pistachio covered by a yellow-red colored soft shell (hull) was evaluated. Fresh pistachio fruit were immersed in different surface treatment solutions of 2% (w/v) chitosan (CT) in 0.5% acetic acid solution, 2 mmol L−1 salicylic acid (SA), and the combination of CT and SA (CT-SA), then packed in perforated polyethylene terephthalate (PET), and stored in a refrigerator for 28 days at 4 °C. Distilled water and 0.5% acetic acid solution containing 0.1% Tween were considered as control treatments. The weight loss and also the peroxide and free fatty acid values of treated fresh pistachio fruit were lower than the controls at the end of the storage period. The activity of superoxide dismutase, catalase, and peroxidase enzymes in the treated pistachio fruit was significantly higher compared to controls (p < 0.05). The SA-treated pistachio fruit shows the lowest activity of polyphenol oxidase. Also, the pistachio fruit treated with CT and SA were lighter (L*), redder (a*), and more yellow (b*) in color as compared with controls, so that the highest sensory scores of color, texture, and overall acceptance were attributed to these treatments. Interestingly, SA treatment resulted in a remarkable superiority of the fruit color score among the samples. Furthermore, the CT and SA treatments alone or in combination significantly reduced the growth of bacteria and fungi. Overall, it can be concluded that SA and CT-SA treatments can assure the safety and quality of fresh pistachio fruit in refrigerated storage.