Improving postharvest quality of fresh pistachios by aloe vera–CMC composite coating functionalized with herbal essential oil

Fresh pistachios are highly perishable due to rapid moisture loss, hull browning, and fungal contamination. This study developed an edible coating based on Aloe vera gel, Carboxymethylcellulose (CMC), and thyme and savory essential oils to extend pistachio shelf life. Using a Central Composite Design (CCD), formulations contained 0-1% Aloe vera gel powder and CMC, and 0–500 ppm of each essential oil. Antifungal activity was evaluated in vitro, while weight loss, fungal contamination, sensory properties, and color changes were assessed in coated pistachios during storage. Under in vitro conditions, both essential oils completely inhibited fungal growth at 400 ppm for thyme and 500 ppm for savory. However, their activity decreased when incorporated into the coating and applied to pistachios. The response surface model predicted that the coating containing savory essential oil would result in the lowest weight loss (1.91%), versus 3.50% for thyme essential oil. The model also predicted that the coating containing 1% CMC provided superior moisture retention, maintaining a moisture content of 36.31%. Optimization identified the coating containing 500 ppm thyme essential oil, 500ppm savory essential oil, and 0.5% Aloe vera as optimal, extending pistachio shelf life from 5– to 6 days to 30 days.