Faculty of Chemical Engineering and Biotechnologies, National University of Science and Technology POLITEHNICA Bucharest, 1-7 Gh. Polizu, 011061 Bucharest, Romania.
Academy of Romanian Scientists, 3 Ilfov St., 050044 Bucharest, Romania.
Int J Mol Sci. 2024 May 31;25(11):6073. doi: 10.3390/ijms25116073.
Food safety and quality are major concerns in the food industry. Despite numerous studies, polyethylene remains one of the most used materials for packaging due to industry reluctance to invest in new technologies and equipment. Therefore, modifications to the current materials are easier to implement than adopting whole new solutions. Antibacterial activity can be induced in low-density polyethylene films only by adding antimicrobial agents. ZnO nanoparticles are well known for their strong antimicrobial activity, coupled with low toxicity and UV shielding capability. These characteristics recommend ZnO for the food industry. By incorporating such safe and dependable antimicrobial agents in the polyethylene matrix, we have obtained composite films able to inhibit microorganisms' growth that can be used as packaging materials. Here we report the obtaining of highly homogenous composite films with up to 5% ZnO by a melt mixing process at 150 °C for 10 min. The composite films present good transparency in the visible domain, permitting consumers to visualize the food, but have good UV barrier properties. The composite films exhibit good antimicrobial and antibiofilm activity from the lowest ZnO composition (1%), against both Gram-positive and Gram-negative bacterial strains. The homogenous dispersion of ZnO nanoparticles into the polyethylene matrix was assessed by Fourier transform infrared microscopy and scanning electron microscopy. The optimal mechanical barrier properties were obtained for composition with 3% ZnO. The thermal analysis indicates that the addition of ZnO nanoparticles has increased thermal stability by more than 100 °C. The UV-Vis spectra indicate a low transmittance in the UV domain, lower than 5%, making the films suitable for blocking photo-oxidation processes. The obtained films proved to be efficient packaging films, successfully preserving plum (Rome) tomatoes for up to 14 days.
食品安全和质量是食品工业的主要关注点。尽管进行了大量研究，但由于行业不愿投资于新技术和设备，聚乙烯仍然是包装中使用最广泛的材料之一。因此，对当前材料进行改性比采用全新的解决方案更容易实施。只有添加抗菌剂才能在低密度聚乙烯薄膜中诱导抗菌活性。氧化锌纳米粒子因其强大的抗菌活性、低毒性和紫外线屏蔽能力而广为人知。这些特性使 ZnO 成为食品工业的理想选择。通过将这种安全可靠的抗菌剂掺入聚乙烯基体中，我们获得了能够抑制微生物生长的复合薄膜，可将其用作包装材料。在这里，我们报告了通过在 150°C 下熔融混合 10 分钟，以高达 5%的 ZnO 获得高度均匀的复合薄膜。复合薄膜在可见光范围内具有良好的透明度，允许消费者观察到食品，但具有良好的紫外线阻隔性能。复合薄膜表现出良好的抗菌和抗生物膜活性，最低 ZnO 含量（1%）即可对抗革兰氏阳性和革兰氏阴性细菌菌株。通过傅里叶变换红外显微镜和扫描电子显微镜评估了 ZnO 纳米粒子在聚乙烯基体中的均匀分散性。对于含有 3% ZnO 的组成，获得了最佳的机械阻隔性能。热分析表明，添加 ZnO 纳米粒子使热稳定性提高了 100°C 以上。UV-Vis 光谱表明在 UV 区域的透光率较低，低于 5%，使薄膜适合阻挡光氧化过程。所获得的薄膜被证明是有效的包装薄膜，成功地将李子（罗马）番茄保存了长达 14 天。
