Effect of Postharvest Application of Thyme Essential oil on Quality and Shelf-life of Pomegranate (Punica granatum cv. Tarom red skin) Fruit

Due to high quality, Iran pomegranate is quite competitive compared to other countries is unrivaled among agricultural products and has great economic importance. Using essential oil is a new idea to reduce postharvest losses and increase the horticultural crop storage life and control of fungal infection. In this context, a factorial experiment based on completely randomized design was conducted to study the postharvest spraying of thyme essential oil on storage life and qualitative characteristics of pomegranate fruit (cv. Tarom red skin)
Pomegranate fruit (cv. Tarom red skin) was prepared and transferred to University of Zanjan, Horticulture postharvest physiology lab. Treatments were included essential oil of thyme at four levels (0, 500, 1000, 1500 mg/l) and the cold time storage (6 °C and 85% of relative humidity) at three levels (one, two and three months (by four replications. In the first experiment, 180 normal pomegranate fruits were treated with thyme essential oil. In the second experiment, fruits were infected with spores of the fungus Aspergillus niger and then treated with essential oil. During experiment, total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, pH, anthocyanin, electrolyte leakage, chilling injury, weight loss and fungal decay were evaluated. Fruit juice TSS was determined with a hand-refractometer at room temperature. TA was determined by titration an aliquot (20 mL) of the juice with 0.1 N NaOH and the results were expressed as a percentage of citric acid. The maturity index (TSS/TA ratio) was evaluated as the TSS/TA ratio. Fruit juice pH was measured using a pH meter. Anthocyanin was performed to method Fuleki & Francis. Electrolyte leakage was measured according to McCollum & McDonald method. Weight loss was measured according to Ershadi method. Chilling injury was measured by Wang method. Decay was visually evaluated and expressed as percentage. An analysis of variance was used to analyze difference between treatments and the Duncan test was applied for mean separation at p