Edible films developed from carboxylic acid cross-linked sesame protein isolate: barrier, mechanical, thermal, crystalline and morphological properties

Films were developed from sesame protein crosslinked with three different carboxylic acids (malic acid, citric acid and succinic acid) at 1, 3 and 5% (w/w, on protein isolate basis). The effect of crosslinking on physical, mechanical, thermal and morphological properties was studied. Succinic acid crosslinked films exhibited least water vapor permeability the highest tensile strength and overall showed superlative properties among other films. X-ray diffraction showed single main crystalline reflection at 20° indicating amorphous structure of films. DSC curves of films indicated single melting peak in the range of 103–161 °C. All films exhibited weight loss in three stages. FTIR exhibited peak at 1700 cm−1 confirming crosslinking reaction between carboxylic acids and protein. Crosslinked films were compact, nonporous and smooth as compared to film from native sesame protein isolate.