Isolation, characterization, and applications of holocellulose nanofibers from apple and rhubarb pomace using eco-friendly approach

Pomace, a byproduct generated from juice processing, contains high quality and quantity of lignocellulosic fibers that can be utilized to extract cellulosic materials for high value applications. Holocellulose fibers contain cellulose and hemicellulose without lignin. This study extracted holocellulose nanofiber (Holo-CNF) from apple (AP) and rhubarb pomaces (RP) using peracetic acid delignification and low energy blending at 5, 15, and 30 min. Holocellulose fibers were easily fibrillated into Holo-CNF with low-energy mechanical treatment due to presence of hemicellulose, which inhibits cellulose-cellulose adhension through steric hindrance and charge repulsion. Morphology of Holo-CNFs depended on type of pomace and blending time. Diameter of Holo-CNFs ranged from 29.8 to 54.0 nm, lower (P < 0.05) than diameter (62.2 nm) of CNF from wood fibers. RP Holo-CNFs had similar length (40.9-44.9 mu m) to CNF (53.0 mu m), but AP Holo-CNFs were shorter (P < 0.05) (16.1-26.0 mu m). Holo-CNF reinforcement in pectin or chitosan films improved mechanical properties and hydrophobicity of films. RP Holo-CNF (5 min blending) enhanced (P < 0.05) stability of oleic acid Pickering emulsion during ambient storage. This study demonstrated the feasibility of converting fruit pomace to Holo-CNF via low-energy and eco-friendly method for various applications. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study extracted holocellulose nanofiber (Holo-CNF) from apple and rhubarb pomaces using a low-energy and eco-friendly method, and investigated its properties and applications. The results showed that Holo-CNF improved the mechanical properties and hydrophobicity of films, and enhanced the stability of oleic acid emulsion.