Enhancing Antibacterial Property of Nanostructured Aluminum Foil by Essential Oil

<br/><br/><b>Contamination is one of the major issues in the food industry. This is often caused by unrestricted bacterial growth. This eventually leads to an overgrowth of bacteria, which has become the most prominent cause of foodborne illnesses. Aluminum is widely used in the food industry for preparation surfaces, as well as food packaging. In this study we introduce an innovative, cost-effective, and environmentally friendly method to develop an antibacterial aluminum foil surface to combat foodborne illnesses. We first use a hot water treatment (HWT) method to produce aluminum oxide nanostructures on aluminum foil, which has recently been shown to possess antibacterial properties. Then the nanostructured Al foil is coated with a layer of tea tree essential oil, which is also known to have antibacterial properties. In this way, we aimed to achieve an enhanced antibacterial activity through synergistic contributions of nanostructures and essential oil. Our results show that HWT Al foil inactivated 93-94% of both gram-negative (Escherichia coli) and gram-positive bacteria (Staphylococcus epidermidis) when compared to the initial bacterial count (control). Tea tree essential oil was shown to be 75% more effective when compared to the control. The cooperative effect of HWT nanostructured Al foil and essential oil inactivated 96-97% of bacteria when compared to the control. The results demonstrate the superior effectiveness and efficiency of HWT nanostructures incorporating an essential oil on them to inactivate both gram-negative and gram-positive bacteria, and its ability to do so in a cost-effective and environmentally conscious manner. The approach also offers the benefit of robustly holding oil on the foil surface due to the superoleophilicity of the nanostructured aluminum oxide layer. In addition, the HWT process can be extended to other forms and types of Al-based materials including Al plates and Al alloys. </b>