Biodegradable film from mango kernel starch: Effect of plasticizers on physical, barrier, and mechanical properties

In this study, the feasibility of mango kernel starch (MKS) as a new film-forming material was studied. A filmogenic solution of MKS (2% w/v) was prepared with different plasticizers (glycerol, sorbitol, PEG-400, and a 1:1 mixture of glycerol and sorbitol) at different concentrations (40, 50, 60, and 70% w/w of starch weight). The films were prepared by a casting technique and the effects of plasticizers on the physical, barrier, sorption, and mechanical properties were investigated. It was noted that glycerol, sorbitol, and their 1:1 combination produced homogeneous, transparent, and smooth films, whereas PEG-400 did not form film with appropriate characteristics. The scanning electron micrographs showed that MKS films had a uniform surface with no holes or fracture. The glycerol-plasticized films exhibited higher solubility, water vapor permeability (WVP) and elongation at break (EAB), but lower tensile strength (TS) than those obtained with sorbitol and combined plasticizers. Glycerol-plasticized films also presented high equilibrium moisture contents at all humidity levels. The TS decreased and the solubility, WVP, and EAB increased with increasing concentration of plasticizers. Low oxygen permeability (OP) was evident in sorbitol plasticized films at 40% plasticizer concentration while lower WVP values were found in combined plasticizers films.