The dried pomegranate peel was powdered using a mixer grinder and 200-g portions of finely-powdered pomegranate peel was blended with 50% ethanol for 2 h at 40 °C in a shaking water bath. The ratio pomegranate peel powder: solvent was 1:10 (w/v). The extracts were through Waterman No. 1 filter paper (Sigma–Aldrich Co., St. Louis, MO, USA) and concentrated under vacuum with a rotary evaporator (Eyela, Rikakikai, Tokio, Japan). The concentrate was dried overnight in an oven at 40 °C to form powder which was stored at 4 °C until further use. The 1.5% of PPE dipping solution was prepared by dissolving PPE in distilled water.
Chitosan were purchased from Shanghai Jinsui Biotechnology Company (Shanghai, China). The degree of deacetylation of chitosan was 90% and the average molecular weight of chitosan was 25 kDa. Chitosan (10 g) was added to 1000 mL of 1% acetic acid and stirred for 1 h at room temperature to obtain 1% of w/w chitosan/acetic acid solutions