Effect of cross-linking modification on structural and film-forming characteristics of pearl millet (Pennisetum glaucum l.) starch

Abstract

Pearl millet starch was modified using epichlorohydrin (EPI) at different concentrations (0.1%; 0.3%; 0.5%; and 0.8%) and evaluated for physicochemical, rheological, in vitro digestibility, and film-forming characteristics. The degree of cross-linking was observed at higher levels (0.5% and 0.8%) of EPI. Upon cross-linking, breakdown and setback viscosity reduced whereas pasting temperature was increased. Storage modulus (G′ ) and loss modulus (G′′ ) value of cross-linked (CL) starches ranged between 2877 to 5744 Pa and 168 to 237 Pa, respectively, during the frequency sweep test. A drastic decrease was observed for steady shear (yield stress and consistency index) characteristics of CL starches. Resistant starch (RS) content was increased after starch modification, which imparts its nutritional values and starch modified at 0.8% had the highest RS content. Modifications of starch at different levels had significant effects on the moisture, opacity, solubility and mechanical properties of films. Outcomes of this study will be helpful to understand the properties of native and CL starches for their potential applications in preparation of edible films.