Antibacterial activity of polyvinyl alcohol (PVA)/ε-polylysine packaging films and the effect on longan fruit

Abstract Biodegradable and antimicrobial films via combing ε-polylysine (ε-PL) and polyvinyl alcohol (PVA) is a promising material for food packaging. We prepared the ε-PL/ PVA films with the ε-PL content of 0%, 1%, 3%, 5% and 7% (wt., relative to PVA) by casting method and their physical and chemical properties were characterized. SEM indicated the surface of ε-PL/PVA films was smooth with well compatibility between ε-PL and PVA at the ε-PL addition content of 1%. The tensile strength and barrier properties for water vapor and oxygen of the ε-PL/PVA films initially elevated and then decreased when ε-PL content exceeded 1%. The ε-PL doped endows antibacterial activity of PVA and the antibacterial property of ε-PL/PVA films was increasing with increase of ε-PL content. Compared with the control, the ε-PL/PVA packaging films could inhibit effectively the pericarp browning and pulp breakdown for longan, consequently the rate of commercially acceptable fruit packaged by ε-PL/PVA films was improved dramatically. However, the effect of ε-PL/PVA on weight loss rate for longan was worse than the control.摘要：通过将ε-聚赖氨酸（ε-polylysine, ε-PL）与聚乙烯醇（polyvinyl alcohol, PVA）复合制备的可生物降解抗菌薄膜，是一类极具应用潜力的食品包装材料。本研究采用流延法制备了ε-PL含量分别为0%、1%、3%、5%和7%（相对于PVA的质量分数，wt.）的ε-PL/PVA复合薄膜，并对其理化性能进行了表征。扫描电子显微镜（Scanning Electron Microscopy, SEM）结果表明，当ε-PL添加量为1%时，ε-PL/PVA复合薄膜表面光滑，且ε-PL与PVA之间相容性良好。当ε-PL含量超过1%时，复合薄膜的拉伸强度、水蒸气与氧气阻隔性能均呈现先升高后降低的变化趋势。掺入ε-PL赋予了PVA薄膜抗菌活性，且ε-PL/PVA复合薄膜的抗菌性能随ε-PL含量的增加而逐步提升。与空白对照组相比，ε-PL/PVA包装薄膜可有效抑制龙眼果皮褐变与果肉软烂，经其包装的龙眼商品果合格率大幅提升。但ε-PL/PVA复合薄膜对龙眼失重率的抑制效果劣于空白对照组。