UC Davis

Microencapsulation facilitates incorporating bioactive volatile compounds into products throughout the food, health, and cosmetics industries. To minimize the number of ingredients when microencapsulating volatile oils, we examined surfactant-free encapsulation of d-limonene in cross-linked alginate microcapsules (CLAMs) via in situ cross-linking during spray drying. Surfactant-free CLAMs (SF-CLAMs) were prepared by forming a Pickering d-limonene emulsion stabilized by calcium carbonate nanoparticles (CaCO3-NPs), combining with alginates, and then spray drying. CaCO3-NPs served as both the emulsifier and the reservoir of alginate cross-linking agent. SF-CLAMs, with a volatile retention of 73.1 ± 4.7% and total limonene content of 13.6 ± 8.6% (w/w, d.b.), exhibited core-shell morphology where CaCO3-NPs surrounded large emulsion cores (∼5 μm) encased in densely cross-linked alginate shells. Limonene was fully retained for up to 4 h in SF-CLAMs in water at 37 °C. Moreover, microencapsulation in SF-CLAMs minimized release in simulated gastric fluid (2.2 ± 0.3% in 2 h) while fully releasing in simulated gastric fluid at 37 °C.