Effects of Exposure to Pulsed Light on Surface and Structural Properties of Edible Films Made from Cassava and Taro Starch

Edible films derived from starch have been proposed as packaging materials. However, they may suffer physicochemical changes due to a variety of factors, such as pulsed light (PL) treatments. In this study, the effect of PL treatment as a crosslinking method on films made from cassava (Manihot esculenta C.) and taro (Colocasia esculenta L. Schott) starch, plasticized with glycerol was evaluated. The average molecular weight, contact angle, moisture content, X-ray diffraction pattern, color, and mechanical and microstructural properties were evaluated. Films subjected to PL showed deterioration compared with control films as demonstrated by an increase in the contact angle, surface roughness, and crystallinity, and a decrease in the tensile strength, transparency, and water content, independent of the amylose content of the starches evaluated. Finally, the surface properties of these materials are defined by intermolecular interactions such as van der Waals-type force interactions (hydrogen bond), new bonds (crosslinking) formed between the biopolymeric chains (starch), and by breakage of covalent bonds.