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 1H 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 2mg/mL, respectively. The antibacterial activity of CGA-Gel was unaffected by conjugation.