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：将ε-聚赖氨酸（ε-polylysine, ε-PL）与聚乙烯醇（polyvinyl alcohol, PVA）共混制备的可生物降解抗菌薄膜，在食品包装领域极具应用潜力。本研究采用流延法制备了ε-PL添加量（以PVA质量计）分别为0%、1%、3%、5%、7%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 microscope, SEM）观测结果显示，当ε-PL添加量为1%时，复合薄膜表面平整光滑，且ε-PL与PVA之间相容性优异。当ε-PL添加量超过1%时，复合薄膜的拉伸强度以及水蒸气、氧气阻隔性能先升高后降低。掺杂ε-PL可赋予PVA基体抗菌活性，且复合薄膜的抗菌性能随ε-PL添加量的提升而增强。与对照组相比，ε-PL/PVA包装薄膜可有效抑制龙眼的果皮褐变与果肉软烂，经其包装的龙眼商品果率显著提升。但ε-PL/PVA复合薄膜对龙眼失重率的调控效果劣于对照组。