Effectiveness of bacteriophage JN01 incorporated in gelatin film with protocatechuic acid on biocontrol of Escherichia coli O157:H7 in beef

Summary A new gelatin-protocatechuic acid (PCA) film with Escherichia coli O157:H7 phage JN01 was developed and characterised. After incorporated with JN01, swelling value, water vapour permeability, water solubility and elongation at break of gelatin-PCA film were not significantly different. The addition of JN01 increased b value and transparency of film, while it decreased L value, a value and tensile strength of film. Moreover, the gelatin-PCA-JN01 film presented antioxidant activity of 60.07%. Furthermore, JN01 could be steadily released from gelatin-JN01 and gelatin-PCA-JN01 films in aqueous solution, and their release rates were 7.56% and 0.12% after 11 h, respectively. The microstructure analysis showed that JN01 particles were clustered and uniformly distributed in film, and the aggregation would be attenuated in the presence of PCA. Meanwhile, E . coli O157:H7 counts were 1.13 log 10 CFU mL −1 and 0.45 log 10 CFU mL −1 lower in gelatin-JN01 and gelatin-PCA-JN01 films compared with pure gelatin film in vitro at 4 °C for 24 h, respectively. After stored at 4 °C for 7 days, Escherichia coli O157:H7 counts were 1.00 log 10 CFU g −1 and 0.80 log 10 CFU g −1 lower in beef packed with these two gelatin films, compared with beef without gelatin film, respectively. In conclusion, the developed gelatin-PCA-JN01 film has potential application in food preservation.