Review Explores Antimicrobial Surface Technologies to Improve Safety of Reusable Food Packaging
Need to Know
- Antimicrobial surfaces could improve the microbial safety of reusable food packaging by reducing microbial adhesion, biofilm formation, and cross-contamination between reuse cycles
- Chemical antimicrobial approaches have demonstrated strong efficacy, but present potential safety and sustainability challenges, including additive migration, reduced recyclability, loss of efficacy over repeated washing, and possible contributions to antimicrobial resistance
- Physically patterned micro- and nanoscale surfaces offer a promising chemical-free alternative, but further research is needed to demonstrate their durability, antimicrobial performance, and potential for microplastic generation under real-world reuse and industrial washing conditions.
As reusable food packaging becomes increasingly important to circular economy efforts, and recent regulations like the EU Packaging and Packaging Waste Regulation (PPWR) drive exploration of reusable packaging schemes, antimicrobial surfaces could help address microbial cross-contamination between cycles, which is a major food safety challenge associated with reuse.
In this context, a review published in Comprehensive Reviews in Food Science and Food Safety examined different strategies for creating antimicrobial surfaces and evaluated their potential suitability for reusable food packaging.
The authors highlighted effective cleaning and sanitization as a critical barrier to widespread adoption of reusable packaging. Plastic surfaces can be susceptible to microbial colonization and biofilm formation, and microorganisms embedded in biofilms can exhibit greater resistance to conventional sanitization than free-floating cells. The authors therefore pointed to preventing initial microbial attachment and biofilm development as an important objective for antimicrobial reusable packaging.
The review categorized antimicrobial surface technologies into several approaches, including functionalized, superwettable, smart, and physically patterned surfaces.
Functionalized Surfaces Show Antimicrobial Activity, but Carry Concerns
Functionalized surfaces incorporate or are coated with antimicrobial agents that actively inhibit or kill microorganisms. Examples included essential oils; antimicrobial peptides such as nisin; organic acids; silver; zinc oxide; titanium dioxide; and antimicrobial polymers.
Some technologies reviewed by the researchers demonstrated strong antimicrobial performance. For example, one previous study developed vanillin-functionalized polymer films that achieved up to 99 percent inhibition of Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes. The films also maintained antimicrobial efficacy after ten reuse and washing cycles, with less than a 0.1 percent reduction in bacterial inhibition.
However, the researchers identified several potential barriers to using functionalized surfaces in reusable packaging, including migration and toxicity concerns associated with some antimicrobial additives, recyclability challenges, loss of efficacy through repeated washing, and possible contributions to antimicrobial resistance (AMR).
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Superwettable Surfaces Prevent Microbial Attachment
The goal of superwettable surfaces is to modify surface wettability to prevent the initial attachment of microbes, thereby preventing biofilm formation.
Chemically produced superhydrophobic surfaces can prevent microbial attachment by repelling liquids, while superhydrophilic surfaces form a hydration layer that can reduce bacterial attachment. Although both approaches demonstrated antimicrobial potential, questions remain about their durability and suitability for repeated food-contact and cleaning cycles.
Smart Surfaces for Food Packaging Not Yet Understood
Smart, or "kill-and-release," surfaces combine bactericidal and antifouling functionality. Such surfaces can respond to environmental stimuli, including changes in temperature or pH, to kill microorganisms and subsequently release microbial debris.
The researchers suggested that this concept could potentially be tailored to reusable packaging, such as by designing a material that is bactericidal under ambient conditions but releases microorganisms during an industrial cleaning process. However, none of the smart-surface studies included in the review specifically addressed food packaging.
Physically Patterned Surfaces Show Promise for Food Packaging
The researchers highlighted physically patterned antimicrobial surfaces as offering potential for reusable packaging because they can function without incorporated antimicrobial agents.
Inspired by naturally antimicrobial structures like cicada wings, lotus leaves, and shark skin, patterned surfaces use micro- and nanoscale topographies to either prevent microbial attachment or physically rupture bacterial cells.
For example, one study included in the review evaluated hierarchical surfaces featuring micro-protrusions and nanospikes. Structures with nanospikes positioned at the base of micro-protrusions reduced attachment by 82 percent for E. coli and 84 percent for S. aureus. Other studies demonstrated that precisely engineered nanopillars could mechanically rupture bacterial cells upon contact.
Because these approaches rely on physical surface architecture, the researchers said they could avoid concerns associated with the migration of antimicrobial additives, compatibility with recycling streams, and AMR.
Still, surface topography is not a universal solution. The review showed that bacterial morphology, cell wall structure, surface wettability, and the dimensions and arrangement of surface features can affect antimicrobial performance. Therefore, surfaces would need to be validated against microorganisms relevant to their intended food applications.
Real-World Reuse and Washing Studies Needed
A significant knowledge gap identified by the review involved the durability of antimicrobial surfaces during repeated use and industrial sanitation.
For physically patterned surfaces, repeated exposure to elevated temperatures and mechanical forces could deform micro- and nanoscale structures and alter their antimicrobial functionality. The researchers also raised the possibility that wear or detachment of nanopillar structures could contribute to microplastic generation.
Overall, the authors concluded that future research should move beyond short-term antimicrobial efficacy testing and evaluate surfaces under realistic reuse conditions, including repeated washing, abrasion, food residue accumulation, aging, and end-of-life recycling.
The researchers asserted that successful implementation will require balancing antimicrobial functionality with food-contact safety, durability, recyclability, and sustainability.
