Optimised model microcapsules of Arabic gum and gelatin a for functional cosmetic applications: From formulation to scale-up using a mesostructured reactor

Microcapsules were developed using Arabic gum and gelatin A through complex coacervation, employing both batch and continuous production methods. Ingredients were chosen to encapsulate diverse hydrophobic core materials with functional properties tailored for cosmetic applications, such as those found in commercial hydrating creams, aiming to enhance their performance through microencapsulation. The formulation was optimised by systematically adjusting key parameters to balance the electrostatic and structural behaviour of the polymers, ensuring ideal encapsulation conditions. The optimised batch formulation (3.5:1 vol-to-volume ratio of core material to emulsifier, stirring at 9500 rpm for 2 min, and 10 % crosslinker concentration) resulted in spherical, multinuclear microcapsules with an average size of circa 60 μm, maintaining structural stability over 45 days. Encapsulation efficiency, defined as the percentage of core material successfully enclosed within the microcapsules relative to the initial amount used, reached up to 89 %. Transitioning to a continuous production method using the NETmix reactor further improved performance, achieving an encapsulation efficiency of 98 %. This was accomplished by performing the emulsification and polymer complexation steps under controlled Reynolds numbers of approximately 358 and 559, sustained over 2 and 4 minutes, respectively.