Ensuring food safety while promoting environmental sustainability remains a pressing challenge in the food industry. Traditional surface sanitizers, such as chlorine-based agents, raise concerns due to their toxicity, environmental persistence, and contribution to food waste. Additionally, synthetic polymers commonly used in antimicrobial formulations exacerbate microplastic pollution, intensifying environmental and regulatory pressures.

This study presents a biodegradable antimicrobial sanitizer for food-contact surfaces. The formulation features thyme essential oil, a natural antimicrobial, encapsulated within a silk fibroin matrix. Blended via 1-minute sonication without solvents, the encapsulation process required no solvent removal. The resulting nanoparticles contained 8% w/w thyme oil and were diluted before antimicrobial testing. This system enhances the stability and controlled release of active compounds, enabling prolonged antimicrobial activity. Controlled release plateaued after 48 hours in Milli-Q water. Remarkably, ~10 times less thyme oil was needed in the nanoparticle formulation to achieve efficacy equivalent to unencapsulated oil, tested against bacteria at OD₆₀₀ = 1. When applied to food-contact surfaces, the formulation effectively reduced contamination by major foodborne pathogens, including Salmonella Typhimurium and Listeria monocytogenes, supporting efforts to reduce spoilage and improve hygiene. After 90 days at room temperature, nanoparticle-treated samples remained visually acceptable, showing extended shelf life in terms of appearance, odor, and general spoilage indicators, while both control and chlorine-treated counterparts became completely inedible.

Using silk, a protein-based biopolymer, eliminates the need for synthetic carriers, providing a safe, microplastic-free alternative. Unlike chlorine-based sanitizers, this system poses minimal risks to human and environmental health, making it suitable for food processing, packaging, and other hygiene-critical uses. The nanoparticle system also demonstrated long-term stability, with no change in particle size after one year.

This research illustrates how biodegradable materials and natural antimicrobials can be integrated into effective sanitation technologies aligned with sustainable food system principles, contributing to reduced foodborne illness, extended shelf life, and environmental responsibility.