Development and characterization of taro starch-casein composite bioactive films functionalized by micellar pomegranate peel extract (MPPE)

Abstract

Starch-casein composite (solid matter content) based bioactive films incorporated with micellar pomegranate peel extract (MPPE) at different concentrations (10, 25, 50, and 100 wt% with respect to base solid matter content) were developed. The extract-free film was used as a control. The bioactive films were characterized for physicochemical, mechanical, barrier, structural, thermal, and bioactive properties. Decreased ζ-potential and surface tension, increased particle size, and improved rheological properties of MPPE added film-forming dispersion (FFD) were recorded. Among all the physical properties of bioactive films, only contact angle was reduced. An increase in MPPE concentration exhibited less hardness, more extensibility, and an excellent barrier to water vapor permeability than the control film. Increased MPPE concentration showed a decline in transparency (%) and lightness (L*) resulting into distinct color to the film. Structural compactness and integrity of the films were confirmed by SEM and XRD patterns. Improved functional interaction and thermal reliability of bioactive films were noted. The interaction patterns between starch-casein composite and MPPE bioactives indicated the development of covalent links. Excellent bioactivities with the slow release of bioactives in hydroalcoholic environment, confirmed by the kinetic study. Remarkable antibacterial effect was noted against E. coli and S. aureus by the films. Overall, increasing the concentration of MPPE in bioactive film showed improved physicochemical strength; hence, prepared bioactive films could be used as food coatings.