Effects of coconut oil concentration as a plasticizer and <i>Yucca schidigera</i> extract as a surfactant in the preparation of extruded corn starch films

Abstract

In this study, extruded films of corn starch (CS) plasticized with coconut oil (CO) (as an alternative plasticizer to glycerol) in the presence of Yucca schidigera extract (YSE) as a surfactant were investigated. It was observed that corn starch films (CSF) plasticized with a lower concentration (15 wt%) of CO showed a better equilibrium of mechanical properties, a higher WVP (5.8 ± 0.2 × 10 −9 g m −1 s −1 Pa −1 ) and percentage of elongation (8 ± 0.5), and a lower Young modulus (99 ± 8 MPa) than those with a higher amount of plasticizer. However, films with Yucca schidigera extract (YSE) as a surfactant showed a decrease in WVP (4.9 ± 0.2 × 10 −9 g m −1 s −1 Pa −1 ), a lower Young modulus (61 ± 2 MPa) and an increase in the percentage of elongation (13 ± 0.4). In order to describe the viscoelastic properties before the extrusion processes in materials in water suspensions and after extrusion process in CSF, rheological and DMTA analysis were performed, showing consistent behaviors for both samples.