Development and characterization of a novel soy protein isolate based composite film enriched with glycyrrhizin nanogel particles.

Abstract

This study focuses on the development and characterization of a novel biodegradable edible film made from soy protein isolate enriched with alginate-glycyrrhizin nanogel(GL-ALG NGP). Nanoparticles of particle sizes below 100 nm were synthesized using glycyrrhizin(GL), calcium chloride and, sodium alginate(SA) through the reverse micro-emulsion/internal gelation method. Soy protein isolate (SPI) based films were prepared by a simple casting procedure by incorporating GL-ALG NGPs in SPI solution in different ratios of (SPI: GL-ALG NGPs) 5:0, 5:1, 2:1, 1:1, and 1:1.5. Glycerol was used as a plasticizer in the film-forming solution. The effects of the proportions of GL-ALG NGPs addition on the thickness, mechanical properties, water vapor permeability, UV barrier performance, antioxidant activity, and antimicrobial property of the obtained films were studied. The GL-ALG NGPs were analyzed using Dynamic Light Scattering. Microstructural studies of obtained films were performed using Scanning Electron microscopy. Results show incorporation of GL-ALG NGPs in soy protein-alginate complex produced smoother, compact, and more continuous matrices as compared to pure SPI films. The test results indicated that blending of SPI with GL-ALG NGPs in the ratio 1:1 increased tensile strength of obtained films by 185%, reduced water solubility to 23.59%, and water vapor permeability to 0.3087 g-mm/m2-d-kPa. Obtained films exhibited good UV barrier performance, antioxidant activity and inhibited the growth of E. coli, S. aureus, Enterobacter sakazakii, and A. niger. So, soy protein isolate-based films enriched with GL-ALG NGPs are active biodegradable edible films that can be used to extend the shelf life of food products.