Influence mechanisms of inert particle-assisted spray freeze-drying on primary and secondary drying processes

As an advanced dehydration technology, spray freeze-drying enables rapid production of premium-grade powders in the food and pharmaceutical manufacturing sectors. This study explores the influence of three inert particle types on the primary and secondary freeze-drying stages, analyzing their effects on moisture content, drying rate, temperature, and processing time. Additionally, this work innovatively incorporates phase-change microcapsules (PCM) to demonstrate the feasibility of actively regulating heat transfer during freeze-drying using phase-change materials. Findings reveal that in the primary drying stage, particles with larger diameters significantly decrease processing duration through enhanced surface exposure; during secondary drying, thermal conductivity and heat-responsive properties of inert particles become critical. Functioning as inert particles, PCM combines an extended heat-transfer surface with latent heat release, achieving temperature stability and optimized energy efficiency across phase-transition zones. In summary, the study comprehensively evaluates various inert particles’ contributions to spray freeze-drying process intensification, proposing a novel active thermal regulation approach based on phase-change materials. Therefore, the findings from this research provide theoretical foundations and technical support for designing efficient, precise drying processes and thermosensitive material preparation.