Antimicrobial surfaces for reusable food packaging

Vast quantities of single-use plastic (SUP) being produced annually; in 2022, 18.5 million tonnes of post-consumer packaging waste were collected in Europe, of which approximately 38% was recycled, 45% sent for energy recovery, and 17% discarded in landfills. If this trend in plastic waste generation continues, the EU is projected to see an additional 19% increase in packaging waste by 2030, with plastics being a major contributor.

Antimicrobial surfaces represent one potential solution for preserving microbial safety and improving the cleanability of reusable food packaging and this is the aim of the review by Farrell et al., analyzing Surface Modification Strategies for Antimicrobial Reusable Food Packaging.

Surfaces and microoganisms

The ability of a microorganism to adhere to a surface and proliferate is largely governed by the physical and chemical interactions between the microbe's outer membrane and the surface. The strength of these interactions is governed by various factors such as surface charge and wettability. Antimicrobial surfaces, which are designed to inhibit the attachment, growth, and survival of microorganisms such as bacteria, viruses, and fungi, are typically fabricated through chemical or physical modifications. 

Chemical modification strategies often involve the application of low-surface-energy coatings to enhance hydrophobicity or the incorporation of antimicrobial agents such as antibiotics or nanoparticles. In contrast, physical approaches manipulate surface topography to disrupt microbial adhesion or actively eliminate cells upon contact.

Antimicrobial surfaces

The classification of antimicrobial surfaces varies across the literature. 

A clasification considers two primary types based on their mechanism of action: microbe-repelling surfaces, which prevent adhesion, and microbe-killing surfaces, which eliminate cells upon contact. 

A more detailed classifications includes antibacterial agent-releasing surfaces, contact-killing surfaces, and antiadhesion or bacteria-repelling surfaces. 
Another classification of antimicrobial surfaces is based on the nature of the surface modification, emphasizing whether the modification imparts microbe-repelling or microbe-killing properties, as shown in the picture.

While all surface types discussed in the review by Farrell et al exhibit antimicrobial functionality, they differ significantly in their primary mechanism of action, fabrication approach, durability, and suitability for reusable food packaging applications. 

Functionalized surfaces 

Functionalized surfaces are one of the four types of surfaces described in the review; the others are super-wettable, smart, and patterned surfaces.

Functionalized surfaces rely on the incorporation of antimicrobial agents, superwettable surfaces inhibit microbial attachment through manipulation of surface wettability, smart surfaces respond dynamically to environmental stimuli, and patterned surfaces utilize micro- and nanoscale topographies to influence microbial adhesion or induce cell damage.

Therefore, the categorization adopted in this review is based on the underlying surface modification strategy and its associated practical advantages and limitations rather than antimicrobial functionality alone.

Functionalized antimicrobial surfaces are manufactured by incorporating or coating materials with agents that actively kill or inhibit microbial growth. These surfaces operate through various mechanisms, dependent upon the chemistry of the incorporated material.

For instance, surfaces fused with nanoparticles, such as silver (Ag), release Ag ions that can bind to and disrupt bacterial cell membranes, interfere with essential enzyme functions, and induce DNA damage, resulting in bacterial cell death.

Similarly, surfaces coated with photocatalytic agents like zinc oxide (ZnO) and titanium dioxide (TiO2) produce reactive oxygen species (ROS) upon exposure to light.

These ROS inflict oxidative damage on bacterial cell components, leading to cell death. Furthermore, antimicrobial peptides such as nisin function by forming pores in the bacterial membrane and disrupting cell wall biosynthesis through interactions with lipid II, thereby compromising the structural integrity of the bacterial cell.

In recent years, significant research has been devoted to evaluating various antimicrobial agents incorporated into food packaging, targeting a range of microbial species.

A promising strategy

Antimicrobial surfaces represent a promising strategy for enhancing the microbial safety and shelf life of food goods supplied in reusable packaging.

Their incorporation could improve consumer engagement and accelerate adoption by facilitating effective decontamination and sanitization, thereby reducing the likelihood of cross-contamination with foodborne pathogens.

By inhibiting the growth and survival of microorganisms responsible for food spoilage and illness, antimicrobial surfaces can provide an added layer of assurance that food is delivered in a safe and hygienic medium. 

Contents

The paper considers following items; it is a free download document available online (see Source)

1 Introduction

2 The Morphology of Microorganisms in Food
2.1 Bacteria
2.2 Fungi
2.3 Viruses

3 Surface Modification Strategies for Antimicrobial Reusable Food Packaging
3.1 Functionalized Surfaces
3.2 Superwettable Surfaces
3.2.1 Superhydrophobic Surfaces
3.2.2 Superhydrophilic Surfaces
3.3 Smart Surfaces
3.4 Patterned Surfaces
3.4.1 Antifouling and Self-Cleaning Surfaces
3.4.1.1 The Relationship Between Surface Roughness and Wettability
3.4.1.1.1 The Wenzel Wetting Regime (proposes a relationship between surface roughness and wettability)
3.4.1.1.2 The Cassie–Baxter Wetting State (proposes a theoretical model to explain the high contact angle values observed on porous materials)
3.4.1.1.3 CAH and Sliding Angle (CAH, contact angle hysteresis)
3.4.1.2 Wettability Favorable for the Removal of Microbes on Reusable Food Packaging
3.4.2 Bactericidal Surfaces

4 Summary of Antimicrobial Surfaces for Reusable Food Packaging

5 Conclusion

Tables

TABLE 1. A summary of studies on the fabrication of functionalized antimicrobial surfaces for food packaging applications.

TABLE 2. A summary of studies on the fabrication of superhydrophobic antimicrobial surfaces for food packaging applications through chemical alteration of surface chemistry.

TABLE 3. A survey of studies on the fabrication of superhydrophilic antimicrobial surfaces through alteration of surface chemistry.

TABLE 4. A survey of studies on the fabrication of “smart” or “kill and release” antimicrobial surfaces.

TABLE 5. A summary of studies on the fabrication of antifouling and self-cleaning antimicrobial surfaces through physical alteration of surface roughness and morphology.

TABLE 6. A survey of studies on the fabrication of contact-killing antimicrobial surfaces through physical alteration of surface roughness and morphology

TABLE 7. Overview of the antimicrobial surfaces reviewed, highlighting their advantages and limitations in the context of reusable food packaging applications.

Sources

Farrell, R., R. Pezzoli, D. M. Devine, and Y. J. Cortese. 2026. “ Antimicrobial Surfaces for 
Reusable Food Packaging: A Comprehensive Review of Functionality and Suitability.” Comprehensive Reviews in Food Science and Food Safety 25, no. 5: e70642. https://doi.org/10.1111/1541-4337.70642
https://ift.onlinelibrary.wiley.com/doi/10.1111/1541-4337.70642?af=R&utm_campaign=newsletter&utm_medium=email&utm_source=rasa_i

Picture
The classification of antimicrobial surfaces based on their mechanism of action and surface modification strategy. 
Figure 2 of the original paper