Stabilization of Pickering emulsions using starch nanocrystals treated with alkaline solution

In this work, Pickering emulsions were successfully prepared using a new Pickering stabilizer prepared from starch nanocrystals by alkaline treatment. Starch nanocrystals produced from different sources (waxy maize starch, NWS; normal maize starch, NCS) were treated with ammonia to investigate the differences in emulsifying properties of the resulting starch nanocrystals (TSNC_nc, produced from NCS; TSNC_wc, produced from NWS). The results of visual observation and confocal laser scanning microscopy revealed that alkaline treatment increased the Pickering-stabilizing capacity of starch nanocrystals, irrespective of starch type. The droplet size of Pickering emulsion stabilized by TSNC_wc was about 5.29 μm, while droplets stabilized by TSNC_nc were about 70.52 μm. The big difference between the droplet size of emulsions stabilized by TSNC_nc and TSNC_wc was attributed to the structural differences between the two kinds of maize starch. The droplet size of Pickering emulsion stabilized by TSNC_wc was significantly smaller than that of Pickering emulsion stablilized by SNC_wc. Zetasizer, transmission electron microscopy and scanning electron microscopy results showed that alkaline treatment decreased the particle size of starch nanocrystals. The present study paves the way for finding new approaches to prepare starch nanocrystals-based Pickering emulsions possessing small droplet sizes.