Preparation and characterisation of Chlorogenic acid-gelatin: A type of biologically active film for coating preservation

Chlorogenic acid (CGA), a type of plant polyphenol, was conjugated onto gelatin (Gel) to prepare a novel coating material for the preservation of fresh seafood. The optimal reaction molar ratio of CGA to gelatin (4:1) was determined according to the CGA content in the CGA-Gel conjugate. CGA was confirmed to be successfully conjugated onto gelatin by 1 H nuclear magnetic resonance and Fourier transform-infrared spectroscopy. The antioxidant activity of CGA-Gel was proven to be higher than that of the free CGA in 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) radical scavenging, hydrogen peroxide scavenging, ferric ion reducing power and lipid oxidation assays. The minimum inhibitory concentrations (MIC) of CGA against Escherichia coli , Pseudomonas aeruginosa , Listeria monocytogenes and Staphylococcus aureus were 1, 1, 2 and 2   mg/mL, respectively. The antibacterial activity of CGA-Gel was unaffected by conjugation.