Cassava and banana starch modified with maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG): A comparative study of their physicochemical properties as coatings
Paula A. Méndez, Ángela M. Méndez, Laura N. Martínez, Brandon Vargas, Betty L. López
Abstract
This study proposes a simple route to obtain starch grafted copolymers from cassava and banana starches chemically modified with amphiphilic maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG). The starches were extracted from cassava (StC) and banana (StB) pulp and characterized by FTIR spectroscopy, amylose content, scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and average molecular weight. Starches were chemically modified with amphiphilic Ma-mPEG in three mass ratios 1:1, 1:2 and 1:3. Thermal behavior and interactions of Ma-mPEG/starch in the St-g-(Ma-mPEG) copolymers were studied by DSC and TGA. The Tg values showed a higher plasticizer effect in the copolymers obtained from StC. Films were formed from StC-g-(Ma-mPEG) and StB-g-(Ma-mPEG) copolymers, thermal and morphological properties were studied. An increase in the mass ratios of Ma-mPEG and the absence of the glycerol in the formulations formed homogeneous films. StC-g-(Ma-mPEG) 1:3 with 2% concentration showed a potential use as coating in strawberries, presenting a lower weight loss (15.5 ± 5.7%) than the control sample (18.6 ± 3.3%).