Structural Characterization of Mango Core-shell Cellulose Nanofibers and Properties Analysis of Stable Pickering Emulsion

In this study, mango core-shell cellulose nanofibers (CNFs) were prepared successfully after hypochlorite bleaching, alkalization TEMPO oxidation and high pressure homogenization. The effects of pH and ionic strength on emulsion stability were also investigated. The results showed that the mango core-shell CNFs prepared by TEMPO oxidation and high pressure homogenization method maintained the basic structure of cellulose, and some hydroxyl groups were oxidized to carboxyl group. The cellulose crystallinity was reduced to 57%, which was more sensitive to temperature, but still maintained high thermal stability. The particle size of Pickering emulsion stabilized by mango core-shell CNFs decreased significantly with the increase of pH. The smallest particle size was 469.5 nm at pH11, and the particle size distribution was more uniform. The 30 day CI was 58.8%, showing good stability. The ionic strength had a great influence on the stability of mango core-shell CNFs Pickering emulsion. Under the ionic strength of 50~100 mmol/L, a large number of positively charged sodium ions aggregated on the surface of CNFs and neutralize the negative charge on the surface, which weakened the electrostatic repulsion between droplets and makes droplets more likely to aggregate, which was not conductive to the stability of the emulsion. In summary, the mango core-shell CNFs could be used as excellent solid particles in Pickering emulsion, which would provide a new for the high value utilization of mango core-shell.