Freeze-Dried Pickering Emulsions with Curcumin: The Role of Stabilizers and Cryoprotectants

This study investigated freeze-dried Pickering emulsions stabilized by a combination of cellulose nanocrystals (CNCs) and sodium caseinate (CAS), with encapsulated curcumin. Our approach focused on the order of CNC/CAS addition and its influence on emulsion properties, along with the effect of three different cryoprotectants (sucrose, d-mannitol, and d-glucose) on the preservation of emulsion droplets. In the study, controlled release of curcumin from freeze-dried emulsions was achieved, attributed to the composition of the stabilizing layer and the cryoprotectant used. The emulsions were partially able to withstand freeze-drying and could be redispersed to samples with droplets bigger than those observed before freeze-drying. The best-preserved droplets came from emulsions stabilized first by CNC particles and then by CAS addition and protected with d-glucose. Transdermal penetration studies revealed that curcumin was mainly present on the skin's surface and at the <i>stratum corneum</i>, with limited penetration into deeper skin layers. Nevertheless, the samples showed outstanding antioxidant activity and no cytotoxicity effects, demonstrating their promising potential to positively influence the healing of the skin.