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 stratum corneum, 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.