Effects of exposure to pulsed light on molecular aspects of edible films made from cassava and taro starch

Abstract

Pulsed light (PL) has been proposed as a method for modifying the physico-chemical properties of edible films by photo-polymerization. Films made from cassava or taro starch plasticized with glycerol were developed and divided into two groups. Films in group 1 were exposed to the maximum PL intensity permitted by the U.S. Food and Drug Administration (FDA) (12 J/cm2), while those in group 2 acted as the controls. The thickness, opacity, density, water solubility, water activity, stability in acidic or alkaline solutions, thermogravimetric (TGA) curves, differential scanning calorimetry (DSC), infrared spectra (ATR-FTIR), nuclear magnetic resonance (1H NMR) and morphology of the films were then evaluated. Edible films prepared from taro starch (lower amylose content) exposed to PL were physically modified through photo-polymerization (cross-linking), resulting in a slight improvement in starch-glycerol interactions. Conversely, starch cross-linking was not evident in the films made from the cassava starch (higher amylose content), and a photo-degradation effect (deterioration) was confirmed.