Development and characterization of starch-based films added ora-pro-nobis mucilage and study of biodegradation and photodegradation

Abstract

Ora-pro-nobis mucilage (MOPN) was incorporated into starch films to improve their mechanical, chemical, and retrogradation properties. Films were made in four MOPN content (0%, 10%, 20%, and 30%) by casting. Films with added MOPN presented antioxidant capacity varying from 3.9% to 23.3%. Chemical cross-links between starch and MOPN were observed in Fourier transform infrared spectroscopy (FTIR) spectrum, resulting in a reinforced network with the greater young modulus (0.02 Pa, control-film, to 2.20 Pa, 30%-MOPN), higher tensile strength (1.34 Pa, control-film, to 4.38 Pa, 30%-MOPN), and reduction in elongation (250.32%, control-film, to 6.55%, 30%-MOPN). Water vapor permeability did not differ statistically between films. In assays photodegradation, higher MOPN content exhibited less shrinkage of films over time and more loss mass in films during 28 days. FTIR spectrum showed that the films increased crystalline regions during storage, which resulted in stronger aggregation between aligned helices. In addition, water molecules were released which allowed a better alignment of the starch chains. Starch-based films added MOPN can alternatively be used as active biodegradable packaging since it is able to form cohesive, flexible films and with antioxidant action. Furthermore, MOPN, especially 30% addition, reduces drastic changes in mechanical properties over time.