Effect of sulfate-ester content and nanocellulose allomorph on stability of amylopectin-xyloglucan water-in-water emulsions

The effect of sulfate ester content on type I allomorph cellulose nanoparticles (CNPs) surface was evaluated in water-in-water emulsions with amylopectin (AMP) dispersed in xyloglucan (XG) phase. In addition, effect of cellulose allomorph type II was also verified. From a single source: microcrystalline cellulose (MCC) sulfated CNCs were isolated by sulfuric acid hydrolysis and subsequently sulfate content was modulated on CNPs surface with partial and quasi-total desulfation, keeping a rod-like particle morphology. MCC was solubilized with phosphoric acid and precipitated in water generating type II spherical nanocellulose allomorph. Particles were characterized by AFM, XRD, zeta potential and their surface groups were quantified by conductometric titration. Effect of adding these particles was evaluate at different concentrations in the phase diagram where XG is continuous phase. It was revealed that sulfated CNCs preference interact with XG increasing its viscosity and stabilizing the emulsions regardless their superficial sulfate content. On the other hand, phosphated nanocellulose interacts less with XG allowing it to migrate to XG-AMP interface and partially stabilize emulsions by Pickering effect.