An emulsion-based tracer solute method for visualizing surface and cross-sectional solute distributions in vacuum impregnated porous food matrices

From the paper

Abstract

Understanding solute behavior during vacuum impregnation (VI) is essential for optimizing functional food design, yet the spatial distribution of specific phases within porous matrices remains largely unexplored. This study developed a rapid visualization framework using phase-specific solutes to quantify solute migration in king oyster mushroom, white radish, eggplant, and apple treated with emulsions under three vacuum levels (−60, −75 and −90 kPa). Cross-sectional images were analyzed via standardized color segmentation and probability-based mapping to reconstruct solute localization. The analysis revealed a previously unreported non-uniform distribution pattern within the internal matrix: dispersed-phase solutes exhibited a preferential accumulation near the core, whereas continuous-phase solutes predominantly co-occurred with them rather than appearing in isolation. Crucially, this central accumulation phenomenon was intricately governed by the complex interplay of multiple factors, such as vacuum levels, macroscopic and microscopic matrix architectures, and free water content. Overall, this framework provides a simple, cost-effective means to visualize phase-specific transport, establishing a methodological foundation for investigating structure–solute interactions and optimizing targeted solute delivery in complex food matrices.