Co-stabilization and properties regulation of Pickering emulsions by cellulose nanocrystals and nanofibrils from lemon seeds

Abstract

The cellulose nanocrystals (LSCNC) and nanofibrils (LSCNF) from lemon seeds were isolated, characterized and used to co-stabilize Pickering emulsions under different LSCNC/LSCNF ratio. The ratio of LSCNC and LSCNF obviously influenced the appearance and microstructure of emulsions. At a fixed total nanocellulose concentration (1 wt%), the LSCNC/LSCNF stabilized emulsions showed a gradual worsening performance with the increase of LSCNF proportion. However, at a fixed LSCNC concentration (0.5 wt%), as LSCNF addition increased from 0 wt% to 1 wt%, the droplet sizes of emulsions gradually decreased, and the viscoelasticity and stability of emulsions increased correspondingly. The obtained emulsions displayed a good pH and ionic strength stability. Notably, introducing LSCNF made LSCNC stabilize emulsions even at low ionic strength (<20 mM). LSCNC can tightly cover the surface of oil droplets, while LSCNF can not only cover the surface of adjacent droplets as a stabilizer, but also form intensive bridging network structure and acted as a thicker to form depletion stabilization, thus achieving the regulation of the emulsion properties. This co-stabilization effect of LSCNC/LSCNF stabilized emulsion depends on the concentration and ratio of LSCNC/LSCNF. These results enrich the approach and theory of nanocellulose in Pickering emulsions application, and also promote the high-value utilization of agricultural by-products.