Fabrication of highly dispersible cellulose nanocrystals for stabilization of Piper betle L. emulsion

Cellulose nanocrystals (CNCs) have been successfully synthesized using carboxymethyl cellulose via hydrolysis with 40% H 2 SO 4 . The fabricated CNCs showed a round shape and relatively low crystallinity (~ 45%), which might be associated with the original cellulose II source. The redispersibility in water could be significantly improved via dialysis with NaOH solution (1 M). The current CNCs could be completely redispersed into water with a concentration up to 1 wt%, even without any sonication steps or high-energy mixing approaches. The particle size of the obtained CNCs ranged from 50 to 60 nm. The negatively charged carboxylate groups in the CNCs structure after NaOH treatment might contribute to the dispersibility and large zeta potential. Essential oil extracted from Piper betle L. leaves (with eugenol ~ 44%, chavibetol acetate ~ 12%, γ-terpinene and β-guaiene ~ 10%, (-)-β-cadinene and 4-allyl-1,2-diacetoxylbenzene ~ 8%) could form the nanoemulsion with the Z-average of 14.5 nm by using Tween 80. However, the stability for long-term storage could not be ensured. The addition of sodium carboxymethyl cellulose (NaCMC) highly increased the viscosity, and the particle size was up to 225 nm. In contrast, the use of the fabricated CNCs (0.1 wt%) for Tween 80-based emulsion showed little change in viscosity but maintained particle size of ~ 54 nm for nearly a month. Enhanced stability could be assigned for the strong ionic repulsion based on the result of zeta potential that could reach − 35 mV. Graphical abstract