Entrapment of carvacrol in zein-trehalolipid nanoparticles via pH-driven method and antisolvent co-precipitation: Influence of loading approaches on formation, stability, and release
Jiyao Zhang, Alkassoumi Hassane Hamadou, Chao Chen, Bin Xu
Abstract
The application of carvacrol (CAR) in the food industry is hindered by its poor water solubility and instability to environmental stresses. Therefore, the possibility of CAR encapsulation in zein-trehalolipid nanoparticles (Z/TL) via phytic acid-adjusted or HCl-adjusted pH-driven method (PAPD or HAPD) and antisolvent co-precipitation (ASCP) was explored (mass proportion of Z-to-TL = 1:1). The efficacy of loading approaches was also compared based on the physicochemical properties of corresponding encapsulation systems. Regardless the variation of CAR mass, obtained PAPD-Z/TL-CAR always displayed smaller size (91.9–151.8 nm), higher ζ-potential (−45.99∼-28.66 mV), and better encapsulation efficiency (93.69–98.84%). At the optimal mass ratio of Z-to-CAR (5:3), PD-Z/TL entrapped CAR in a more hydrophobic microenvironment than their ASCP counterparts. The self-assembly in spherical Z/TL-CAR including mainly hydrophobic interaction, hydrogen bonding, and electrostatic interactions, were more intense in PD-ones, especially using PA as the acidifier. These structural features are responsible behind the stronger resistance to thermal degradation, lower instability index after centrifugation sedimentation, wider pH range of colloid stabilization, and higher retention of encapsulated carvacrol mass after 21 days storage observed with PAPD-Z/TL-CAR. Moreover, the three encapsulation systems all demonstrated the acceptable aqueous re-dispersibility and controlled-release over a period of 168 h. Overall, PAPD was more appropriate to produce prolamin-amphiphilic emulsifier colloidal particles as prominent carriers for CAR and its analogues.