Prolong the shelf-life and quality attributes of ready-to-eat pomegranate arils using PLA/ZnO nanoparticle/ Zataria multiflora essential oil nanocomposite film

Abstract

The dried pomegranate (Punica granatum L.) arils have several health benefits and are in demand worldwide. Therefore, in the current study, the wrapping effects of Poly L-lactide (PLA) activated with zinc oxide nanoparticles (ZnO NPs, 1.5% w/w) and Zataria multiflora Boiss. essential oil (ZEO, 1 and 1.5% w/w) was studied on pomegranate arils' storage-life extension in cold storage. The arils were analyzed periodically for properties of physiochemical (weight loss, pH, total soluble solids, color measurement, antioxidant activity and sensory attributes) and microbial (total aerobic bacteria and total fungi counts). Results showed that the ZEO causes to decrease and ZnO causes to increase of pH during storage. Also, the active films were more effective than the control film in maintaining TTS and preventing weight loss of arils. The PLA/ZnO/1.5% ZEO sample had the highest phenolic content (∼520 mg/100 ml in juice) and antioxidant activity (∼90%) on day 15. Nevertheless, the effect of ZEO on the color properties of arils was more than ZnO, and 0.5 and 1.5% ZEO-PLA, showed the highest a* (55.14) and b* (31.30) with fresh arils, respectively. The microbial test results showed that ZEO was more effective in controlling bacterial growth than ZnO. Based on atomic absorption spectrophotometer measurement, minimal amounts (∼29 mg Kg− 1 sample) of Zn2 + ions released into arils were observed. Generally, the active PLA could be used as a safe and effective way to prolong the storage life of arils in refrigerated conditions.