Nano-encapsulation of pomegranate (Punica granatum L.) peel extract and evaluation of its antimicrobial properties on coated chicken meat

Pomegranate peel extract (PPE) is a valuable source of bioactive compounds, with antimicrobial activity. On the other hand, reducing the extract particle size to a nano-scale due to the increase in the surface-to-volume ratio can increase its effectiveness. The alginate nanospheres containing PPE were prepared through water in oil (W/O) emulsification and external gelation with calcium chloride nanoparticles. The optimum ratios for alginate:PPE and alginate:calcium chloride nanoparticles, based on encapsulation efficiency and nanospheres size, were 4:1 and 9:1, respectively (p < 0.05). The particle size and encapsulation efficiency of optimum nano-capsules containing PPE were 205.1 +/- 0.1 nm and 83.90 +/- 0.53%, respectively. The morphology and physical stability of optimum nano-capsules were further studied. After preparation of PPE-loaded nano-particles, the antimicrobial activity of the nanospheres containing 200 mg/ml PPE were determined by agar diffusion method and the results were compared with those obtained using 200 mg/ml non-encapsulated PPE. Data showed that nano encapsulated PPE has larger inhibition zone against tested bacteria after 48 h incubation (p < 0.05). As a novel coating, the nanosphere containing PPE showed higher microbial inhibitory effects in fresh chicken breast meat during the storage time (at 4 degrees C for two weeks), compared with those obtained using alginate containing PPE and free PPE. It seems, because of controlled release of PPE through nanospheres, a higher antimicrobial activity was achieved, so it had the potential to use as an effective antimicrobial agent in food products.