Studies on the role of gelatin as a cryo- and lyo-protectant in the stability of capsicum oleoresin nanocapsules in gelatin matrix

The purpose of this study was to determine the effect of freezing process in the absence or presence of excipients on the stability of capsicum loaded nanocapsules (NC) during freeze-thawing and freeze-drying procedures. Capsicum loaded nanocapsules were prepared by the modified-emulsion–diffusion method combined with the microfluidization method. The prepared samples were frozen at freezing temperatures of −40, −20, and −15 °C to study the effects of cooling temperature on the properties of the capsicum oleoresin loaded nanoparticles. From results, a relatively high freezing temperature had an effect on the maintenance of nanocapsule size after freeze-thawing and freeze-drying. Regarding the addition of excipients, gelatin and κ-carrageenan played roles as cryoprotectants and lyoprotectants, and represented R values of 1.01 and 1.13 in size comparisons before and after treatment, respectively. Furthermore, the morphologies of NC made with gelatin or κ-carrageenan were conserved after freeze-drying showing spherical forms according to electron microscope observations.