La Storia A, Ercolini D, Marinello F, Mauriello G
Dept. of Food Science, School of Agriculture, Univ. of Naples Federico II, Via Universitá 100, 80055 Portici, Italy.
J Food Sci. 2008 May;73(4):T48-54. doi: 10.1111/j.1750-3841.2008.00713.x.
Antimicrobial agents can be used to give antimicrobial properties to polymeric materials used to envelope foods for packaging purposes. In this study, we exploited an atomic force microscopy (AFM) analysis for the characterization of plastic films activated with antimicrobial agents. The aim was to acquire information on the distribution of the antimicrobials on plastic materials with the ultimate scope of understanding the mechanisms of interaction between antimicrobials and materials to be used for food packaging. Four polyethylene films differing in linear, EVA, and erucamide content were activated by 3 different bacteriocins as antimicrobials, namely, nisin and bacteriocins Bac162W from Lactobacillus curvatus and BacAM09 from Lactobacillus plantarum. The spectrum of activity of the bacteriocins was assayed and shown to include several strains of Listeria monocytogenes. The plastic films were activated by a previously developed coating procedure and the surfaces of the active films were examined by AFM. In addition, roughness parameters related to the single surfaces were investigated by an appropriate software. Significant differences were found between the bacteriocin activated and control (nonactivated) films and the activated surfaces showed lower values of average roughness and surface area ratio. It was not always possible to obtain a homogeneous distribution of the bacteriocin preparation following the coating procedure. This result was dependent on the bacteriocin used and its distribution on the different plastic films. Overall, the bacteriocin Bac162W showed the most homogeneous distribution while surfaces treated with nisin, showing a sort of microtexturing, always gave the highest roughness values. Although the issue needs further investigation, the connection between AFM imaging, roughness, and antimicrobial distribution on active packaging showed the potential to improve the understanding of the interactions between plastic films and antimicrobial preparations that can be important for the innovation in food packaging and science.
抗菌剂可用于赋予用于食品包装的聚合材料抗菌性能。在本研究中，我们利用原子力显微镜（AFM）分析来表征用抗菌剂活化的塑料薄膜。目的是获取有关抗菌剂在塑料材料上分布的信息，最终目的是了解抗菌剂与用于食品包装的材料之间的相互作用机制。四种线性、EVA和芥酸酰胺含量不同的聚乙烯薄膜分别用3种不同的细菌素作为抗菌剂进行活化，即乳酸链球菌素以及来自弯曲乳杆菌的细菌素Bac162W和来自植物乳杆菌的细菌素BacAM09。对这些细菌素的活性谱进行了测定，结果表明其对几种单核细胞增生李斯特菌菌株具有活性。通过先前开发的涂层程序对塑料薄膜进行活化，并通过AFM检查活性薄膜的表面。此外，使用适当的软件研究了与单个表面相关的粗糙度参数。在细菌素活化膜和对照（未活化）膜之间发现了显著差异，活化表面的平均粗糙度和表面积比的值较低。按照涂层程序并不总是能够获得细菌素制剂的均匀分布。这一结果取决于所使用的细菌素及其在不同塑料薄膜上的分布。总体而言，细菌素Bac162W的分布最为均匀，而用乳酸链球菌素处理的表面呈现出一种微观纹理，粗糙度值始终最高。尽管这个问题需要进一步研究，但AFM成像、粗糙度和活性包装上抗菌剂分布之间的联系显示出有潜力增进对塑料薄膜与抗菌制剂之间相互作用的理解，这对于食品包装和科学创新可能很重要。
