Properties and application of bilayer films based on poly (lactic acid) and fish gelatin containing epigallocatechin gallate fabricated by thermo-compression molding

Abstract

An alternative approach towards production of active bilayer films based on poly (lactic acid) (PLA) and fish gelatin incorporated with epigallocatechin gallate (EGCG) fabricated by thermo-compression molding was investigated. This strategy permitted the reduction of production times and avoided the uses of inorganic solvents. Thermo-compression molded bilayer films showed good handling, transparency and low water vapor permeability. The incorporation of EGCG promoted interactions with gelatin, as shown by Fourier transform infrared spectroscopy. These interactions contributed to homogeneous structures, as observed by scanning electron microscopy. Bilayer films with 12 wt % EGCG showed good mechanical properties, high water and UV–visible light barrier properties as well as a high DPPH radical scavenging activity. These bilayer films were used to produce bags, in which striped catfish slices (SCS) were packaged. After 7 days of storage at 4 °C, SCS packaged in bags prepared with12 wt % EGCG had lower psychrophilic bacteria count, weight loss, peroxide value, and thiobarbituric acid reactive substances (TBARS) value along with higher docosahexaenoic acid (C22:6 n-3) content than those packaged in bags prepared without EGCG or in LLDPE bags. No difference in overall likeness score was found among all the samples packaged in different bags after 7 days of storage. Therefore, PLA/gelatin bilayer films containing 12 wt % EGCG possessed satisfactory film properties with augmented antioxidant activity, and thus they could be used as active food packaging, especially for fish slices with high lipid content.