Lignocellulose nanocrystals from pineapple peel: Preparation, characterization and application as efficient Pickering emulsion stabilizers

Abstract In this study, the pineapple peel treated with different degrees of delignification was used to isolate lignocellulose nanocrystals (LCNC) by sulfuric acid hydrolysis. Controlling delignification treatments can adjust the morphology and structure of pineapple peel and the retention of lignin, thereby achieving the regulation of the properties of LCNC, such as morphology, crystallinity, hydrophobicity and rheological properties. The results of atomic force microscope (AFM), confocal laser scanning microscopy (CLSM), UV/visible (UV–Vis) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the presence of lignin in LCNC, showing a rod-like structure with the distribution of lignin. Regulating delignification of pineapple peel can adjust the average length (310 ∼ 460 nm), diameter (19 ∼ 38 nm), crystallinity (61% ∼ 71%) and hydrophobicity (contact angle 84° ∼ 60°) of the obtained LCNC by acid hydrolysis, and influence the performance of its stabilized Pickering emulsions. This work confirms that the properties of LCNC can be controlled through adjusting delignification degree, possessing great significance for the high value utilization of lignocellulosic agricultural waste.