Effect of bacterial cellulose based active film containing Rosemary (Rosmarinus officinalis) essential oil and ZnO nanoparticles on chemical, microbial and nutritional properties of ready to eat pomegranate arils during cold storage

Nowadays, the using of ready to eat food products is growing and the shelf life increasing of these products has been attracted attention of researchers. The aim of this research was to investigate the effect of bacterial cellulose based biodegradable active film containing Rosemary essential oil (RE) and ZnO nanoparticles (at concentrations of 2.5 and 5% wt. of cellulose) on the chemical properties, nutritional components and microbial quality of ready to eat pomegranate arils during 12 days storage at 4 °C. Also the effect of UV irradiation at 245 nm for 10 min on the performance of the ZnO loaded films was evaluated. Results exhibited that the RE causes to decrease and ZnO causes to increase of pH during storage. Also, the active films were more effective than control film in the maintenance of arils Brix. The 5% ZnO loaded and UV irradiated sample had the highest antioxidant activity (43.5%) and vitamin C content (64.3 mg/ml) at day 12. Nevertheless, the effect of RE on the color properties of pomegranate arils was more than ZnO and 5% RE loaded sample, exhibited the highest a value (18.00) and the lowest total color difference (1.61) with fresh arils. The results of microbial evaluation showed that the ZnO nanoparticles were more effective than RE in the control of bacterial growth and also the UV irradiation increased the antimicrobial activity of ZnO. The yeast and mold content was increased up to day 4 but was diminished after that. Generally, the pomegranate arils stored in contact with irradiated ZnO loaded active films, had the best chemical and microbial quality attributes but the effect of RE on the color preserving of arils was more than ZnO.