Bioactive edible films: Development and characterization of gelatin edible films incorporated with casein phosphopeptides

Abstract

This study aimed to investigate the effects of bioactive casein phosphopeptides (CPPS) (0, 0.1, 0.2, 0.3 and 0.5% (w/v)) on physico-mechanical, structural, antimicrobial and antioxidant characteristics of gelatin-based films. The results demonstrated that the addition of CPPs to gelatin films significantly decreased solubility and water vapor permeability (WVP) of the treatments G-CPP0.1, G-CPP0.2 and G-CPP0.3, but the optimal treatment was achieved in treatment G-CPP0.1 (4.46 × 10−12 g (m s Pa)−1 of WVP and 43.5% of solubility). The light transmittance decreased with increasing CPPs concentration in the films, achieving the lowest transmittance (0–11.2%) of UV light in the 200–350 nm range. Treatment G-CPP0.1 showed improved mechanical properties such as the highest TS (18.14 MPa) and EAB (84.1%). FTIR and DSC analysis indicated suitable interactions between gelatin and CPPS functional groups in the sample G-CPP0.1. Gelatin-CPPS films showed good inhibitory effects against the tested Gram-positive microorganisms (Staphylococcus aureus and Bacillus cereus) by increasing the concentration of CPP in the composite film. In addition, they presented effective antioxidant activity by DPPH test (2,2-diphenyl-1-picryl hydrazide). In general, the results showed that the gelatin-CPPS edible films with lower CPP concentrations (0.1–0.2% of CPP) could be potentially used in food packaging to ensure the quality of food products, due to their suitable physico-mechanical properties and enhanced bioactive characteristics.