Facile isolation of cellulose nanofibrils from agro-processing residues and its improved stabilization effect on gelatin emulsion

In this study, the pineapple peel cellulose nanofibrils (PCNFs) were facilely isolated by a dilute alkali assisted ball milling technique, then used to adjust the stabilization of low internal phase oil-in-water emulsions (oil phase 30 vol%) stabilized by gelatin (GLT, 1 wt%). The ball milling with the aid of NaOH solution (3 wt%) efficiently promoted the purification and defibrillation of cellulose through a one-pot approach, showing an average length of 0.77 μm and crystallinity index of 43.5 %. With the increase of PCNFs concentration (0–1.0 wt%), the emulsions showed an increased droplet size (51.2–76.9 μm) and a gradually decreasing bottom water layer. The apparent viscosity, storage modulus (G') and loss modulus (G") of emulsions evidently increased with increasing PCNFs addition. The result of confocal laser scanning microscopy (CLSM) confirmed the stabilization mechanism of GLT/PCNFs emulsions, involving the interface adsorption by GLT and the formation of viscoelastic network structure by PCNFs. The environmental stabilities of GLT emulsion could be improved by introducing PCNFs, except for at high ionic strength (> 100 mM). Notably, PCNFs effectively avoided the adverse effect of GLT isoelectric point (pH 5) on the stability of emulsion.