Characterization of Antimicrobial Properties of Salmonella Phage Felix O1 Embedded in Low-Density Continuous Xanthan Coatings on Poly(lactic acid) Films

Introduction: Salmonellosis is one of the top three most common and serious forms of foodborne illness globally. While protocols are in place to sanitize meat products, accidental incidental contamination at points throughout the production process still remains a problem. Food packaging is an important component of preventing food borne illness by protecting products from external contamination and inhibiting growth of pathogenic and spoilage bacteria already present. However, conventional packaging is susceptible to protective failure enabling the development of spoilage and serious foodborne illness.

Purpose: The purpose of the study was to develop and evaluate the efficacy of a Salmonella Felix O1 bacteriophage coated PLA packaging film to control the growth of Salmonella spp. on surface of meat.

Methods: Concentrated Salmonella phage Felix O1 was incorporated into a thin layer of xanthan polymer adhered to PLA film. Salmonella growth on both agar and beef surfaces in contact with this phage coated film was compared with control films over time.

Results: Salmonella growth was significantly inhibited in the presence of the bacteriophage coated packaging film both on plates (P<0.05) and in semi-solid culture growth curve assays (P<0.05). No inhibition was evident from the control groups. Recovery of phage released from coating showed less than one-log reduction in titer from input bacteriophage concentrations. Preliminary analyses show more than a one-log reduction in Salmonella persistence in surface contaminated meat at 10°C over three days following contamination when wrapped aerobically with the phage coating, relative to phage free control xanthan coatings, for an overall 10³ fold reduction.

Significance: Similar approaches could be used to develop packaging films inhibitory to diverse foodborne pathogens and spoilage bacteria, thereby significantly reducing the incidence and severity of these pathogens in addition to extending product shelf life.