Optimization of Coaxial Spray-Drying for the Encapsulation of Tenebrio molitor Protein Hydrolysate Exhibiting DPP-IV Inhibitory Activity

This study aims to optimize the encapsulation of Tenebrio molitor protein hydrolysate exhibiting dipeptidyl peptidase-IV (DPP-IV) inhibitory activity using coaxial spray-drying, a novel technique that enhances the stability, protection, and efficacy of bioactive compounds for use in functional foods. The variables investigated included solids content in the core feed, solids content in the shell feed, and shell/core flow ratio. The resulting microcapsules were characterized based on their morphology, particle size distribution, yield, surface nitrogen content, and in vitro DPP-IV inhibitory activity. These parameters were systematically investigated using a design of experiments and optimized through response surface methodology. The results showed that a maximum yield was achieved with 30% solids in the core and 19.73% solids in the shell. Furthermore, the shell/core flow ratio had the most significant impact on both the surface nitrogen content and the DPP-IV inhibitory activity of the capsules. Optimal conditions for minimum protein migration and maximum bioactivity values were observed at the highest solid concentration, requiring a compromise between process yield and hydrolysate protection while maintaining a high shell/core ratio.