溶菌酶与ε-聚赖氨酸盐酸盐复合涂膜的制备及性能分析

Preparation and Properties of Lysozyme and ε-Polylysine Hydrochloride Composite Coating

分析溶菌酶和ε-聚赖氨酸盐酸盐的添加量对壳聚糖和普鲁兰多糖复合涂膜理化性能的影响,制备含抑菌剂(3 mg/mL溶菌酶和1.8 mg/mLε-聚赖氨酸盐酸盐)的复合涂膜(CS-PUL-A),并比较CS-PUL-A与无抑菌剂复合涂膜(CS-PUL)的性能差异。结果表明:抑菌剂的添加改善了复合涂膜的韧性及对气体和水的阻隔性能,而对其拉伸强度和透光性影响不明显。进一步分析复合涂膜对鱼类优势腐败菌(荧光假单胞菌)的抑菌性能,结果表明:CS-PUL-A比CS-PUL具有更强的抑菌作用,并且在培养初始12 h具有一定杀菌作用;CS-PUL-A较CS-PUL能导致更多菌体核酸和电解质外漏,使菌悬液的电导率升高,说明CS-PUL-A增强了对菌体细胞膜完整性和通透性的破坏;涂膜处理也降低了样品中碱性磷酸酶的活性;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果表明CS-PUL主要影响了菌体小分子质量蛋白,而添加抑菌剂后也影响了菌体大分子质量蛋白。扫描电子显微镜观察结果进一步证实了CS-PUL-A对细菌的损伤。总地来说,CS-PUL-A较CS-PUL具有更好的物理化学性质和抑菌性能,有望应用于食品保鲜领域。

In the present study, a chitosan-pullulan composite coating(CS-PUL-A) containing antibacterial agents(3 mg/mL lysozyme and 1.8 mg/mL ε-polylysine hydrochloride) was prepared, and its properties were compared with those of its counterpart without antibacterial agents(CS-PUL). The results showed that addition of antibacterial agents improved the toughness and gas and water vapor barrier properties but had little effect on the tensile strength and light transmission of the composite coating. In addition, CS-PUL-A had stronger antibacterial activity against Pseudomonas fluorescens(one of the dominant specific spoilage organisms in fish) than did CS-PUL, and the activity appeared after cultivation for 12 h. Compared with CS-PUL, CS-PUL-A could result in increased leakage of intracellular nucleotides and electrolytes and subsequently higher conductivity of the cell suspension, indicating that CS-PUL-A more severely damaged the cell membrane integrity and permeability. The coating treatment also reduced the activity of alkaline phosphatase in the suspension. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) indicated that CS-PUL mainly affected small proteins, while CS-PUL-A affected both small and large proteins. Scanning electron microscopy further confirmed the damage to bacterial cells caused by CS-PUL-A. In summary, CS-PUL-A exerted better physicochemical properties and antibacterial properties than CS-PUL and could be potentially used in food preservation.