Production of cellulose nanocrystals from pistachio shells and their application for stabilizing Pickering emulsions

This study presents isolation and characterization of cellulose nanocrystals (CNC) from pistachio shell and their application to stabilize Pickering emulsion. Pistachio shell (PS) is an agro-waste with an attractive source of cellulose. Alkali and bleaching treatments were performed for removing hemicellulose and lignin and purification of cellulose, while cellulose nanocrystals were obtained by acid hydrolysis. Hydrolysis using H2SO4 was very severe that led to formation of amorphous structures. While, hydrolysis reaction by HCl for 180 min in concentration of 3 M was recognized as the best conditions to extract CNCs with yield of 77.1% and crystallinity of 79.4%. FE-SEM images represented both rod-like and spherical shapes of CNC and TEM image showed particles with mean diameter of 68.8 ± 20.7 nm. Chemical structure and thermal properties of CNC were characterized by FTIR and TGA analysis. In order to evaluate emulsifier ability of CNCs, different concentrations of CNCs were dispersed in an oil in water emulsions as the Pickering agent. By increasing the CNC concentration, stability of emulsions against heating, stresses and storage time enhanced while the mean diameter of oil droplets decreased. The results of this study indicated high potential of CNCs as an environmental friendly material for food emulsion preparation.