Improvement of the safety of scallops through the application of calcium alginate films with the controlled release of Vibrio bacteriophage

Abstract

The increase in the population of antibiotic-resistant bacteria has prompted the exploration of food safety alternatives, such as bacteriophages (phages). This study aimed to develop anti-Vibrio films with controlled phage release and focused on the shelf life extension of scallops. VPy01, a newly isolated lytic phage, demonstrated a rapid bactericidal effect against V. parahaemolyticus in 1 h at a multiplicity of infection of 1. It was stable in a wide range of temperature (-18°C to 60°C), pH (4−11), and salinity (0–6%) conditions. As a genetically secure agent, VPy01 was loaded into a sodium alginate (SA, 2%, w/v) film, and glycerol was used as a plasticizer. It was then cross-linked with various calcium salts (CaCl₂, CaCO₃, hydroxyapatite, and CaSO₄). The SA film cross-linked with CaCl₂ (SA-CaCl₂) efficiently released VPy01, showing remarkable vibricidal effects (>2-log CFU). The SA-CaCl₂ film with well-dispersed phages improved hardness, elongation at break, and oxygen barrier ability. When applied to scallops, the SA-CaCl₂ film preserved the hardness and weight of scallops and reduced Vibrio by 1.8-log CFU/scallop. Thus, their shelf life was extended. Overall, this study highlighted the potential of VPy01-loaded calcium alginate films for the extension of scallop shelf life, contributing to sustainability in the seafood industry.