Preparation and characterization of active and intelligent films based on fish gelatin and haskap berries (Lonicera caerulea L.) extract

Haskap berries (Lonicera caerulea L.) are rich in polyphenols and possess potential health-promoting effects. In this study, polyphenols were extracted from haskap berries and further incorporated into fish gelatin (FG) to develop active and intelligent packaging films. Results showed anthocyanins and phenolic acids were the main polyphenols in haskap berry extract (HBE). Scanning electron microscopy showed the cross-sections of FG-HBE films were smooth and uniform. Fourier transform infrared spectroscopy revealed intermolecular hydrogen bonds formed between the hydroxyl groups of polyphenols in HBE and the amino/hydroxyl groups in FG. The crystallinity of FG film was enhanced by the addition of HBE. Moreover, the incorporation of HBE significantly increased the total color difference value, water vapor and UV-vis light barrier properties, tensile strength, and antioxidant ability of FG film. Due to high anthocyanin content in HBE, FG-HBE films were pH-sensitive and exhibited visible color changes as a function of pH. Notably, FG-HBE film containing 1 wt% of HBE was more appropriated to be used as the freshness indicator of shrimp. Our results suggest FG-HBE films can be applied as novel as antioxidant and intelligent food packaging films in food industry.