Isolation of microcrystalline cellulose (MCC) from pistachio shells and preparation of carrageenan-based composite films

Abstract

Utilizing agricultural waste for material innovation, particularly in food packaging, is an emerging trend aimed at enhancing sustainability and reducing environmental impact. In this study, the goal was to valorize agricultural waste by isolating microcrystalline cellulose (MCC) from pistachio shell powder (PSP) and integrating it into carrageenan films as a filler. Alkaline hydrogen peroxide (AHP) was used to extract PSP fiber at various AHP liquor ratios (NaOH:H2O2), followed by hydrochloric acid hydrolysis of the PSP fibers. Detailed analyses assessed the impact of AHP concentration on the thermal, morphological, microscopic, and crystalline properties of the resulting MCC. Elevated NaOH and H2O2 ratio in the AHP process notably improved the MCC's thermal stability and crystallinity index. FTIR spectroscopy indicated the efficient removal of amorphous regions and impurities, such as lignin and hemicellulose, during AHP pre-hydrolysis. The 4.0:4.4 AHP liquor ratio emerged as particularly promising, considering thermal stability, impurity removal, and crystallinity index. Carrageenan films with the derived MCC showed improved UV resistance, oxygen barrier, thermal stability, and mechanical properties. This research highlights the potential of pistachio shell-derived MCC as a sustainable filler, emphasizing a novel strategy for repurposing agricultural waste.