Physicochemical characteristics and emulsification properties of cellulose nanocrystals stabilized O/W pickering emulsions with high -OSO3- groups

The emulsion stability of sulfated cellulose nanocrystals (CNCs) (with different sulfur contents of 0.436, 0.882 and 1.499 mmol/g, representing as CNCs-L, -M and -H) on medium chain triglyceride (MCT) oil/water (O/W, 30/70, v/v) Pickering emulsions (PE) was modulated by tuning sulfuric acid (H2SO4) concentrations at 22.72, 37.03 and 46.86 wt% during hydrolysis of microcrystalline celluloses (MCCs). CNCs-L, -M, or -H as the sole stabilizer was incorporated into O/W PE for improving emulsification and dispersion stabilities. CNCs-H had smaller diameter (64.74 nm), higher Zeta-potential (ZP) (- 47.96 mV) and crystallinity index (CrI) (86.2%), and lower average length (75.74 nm) and a width (10.31 nm) than those of CNC-M and CNC-L. Fourier transform infrared spectrometer (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis indicated that -OSO3- groups from the sulfuric acid (H2SO4) were incorporated to the surface of CNCs during acid hydrolysis. The CNC-H had the highest storage stability, followed by CNCs-M and L, consistent with their sulfur content and surface charge (SC) of O/W PE (46.25, 52.33 and 62.24%), respectively. This study indicated that sulfated CNCs had great potential as fillers and emulsifiers of network structure of emulsion for application in food and other fields.