A natural, cellulose-based microgel for water-in-oil emulsions

Non-derivatised cellulose is generally assumed to have poor surface activity and therefore be unsuitable as a water in oil (W/O) emulsifier. In this work, a “natural” cellulose microgel (CMG) is fabricated via a top-down approach and used to stabilize W/O emulsions, without employing chemical modification. The cellulose is coagulated from an ionic liquid through a solvent-exchange process, in the presence and absence of added sunflower oil, in order to tune the cellulose morphology and properties. Detailed characterization of the nature of these microgels and the effect of the solvent change sequence on their emulsifying properties was investigated. In the presence of oil, Fourier transform infrared (FTIR) spectroscopy confirmed the retention of oil in the coagulum during regeneration and the resultant CMGs were more easily dispersed in oil than water, suggesting the fabrication of a “hydrophobic” microgel. Confocal microscopy confirmed the adsorption of CMGs to the water-oil interface and W/O emulsions of up to 20 vol% water displayed good stability over at least 1 month. This study therefore describes a “novel” route to W/O stabilization using a natural emulsifier, which could be then used as a method of reducing fat and sugar in food products.