Fabrication of rice flour films reinforced with hemp hurd and loaded with grapefruit seed oil: A simple way to valorize agro-waste resources toward low cost materials with added value

Abstract

Novel biodegradable films based on rice flour loaded with hemp hurd powder and grapefruit seed oil, as a mixture of natural compounds with potential antimicrobial activity, were fabricated and morphologically analyzed. Mechanical and thermal analysis were correlated to the hemp hurd content showing that no increase in thermal stability occurred for the rice flour composite while a noticeable improvement in mechanical properties was achieved after the addition of hemp hurd (up to 300 % of the pure rice flour film for a reinforcement loading of 20 % wt). Barrier properties were then studied aiming of evaluating the effect of hemp hurd on water sorption and diffusion. The decrease in polar site of rice flour and the hydrophobic character of either hemp hurd or essential oil led to a reduction of either the sorption parameter (about 85 % with a hemp hurd amount of 20 %wt) or the diffusion one (up to 96 % with a hemp hurd amount of 20 %wt). Optical properties appeared to not be pretty sensitive to hemp hurd presence. The release of a grapefruit seed oil was then studied through a second-order model and correlated with the effect of hemp hurd loading.