Structural and physicochemical characterization of maltodextrin (starch-derived polysaccharide) microcapsules loaded with phenolic-rich yerba mate extracts

Phenolic compounds are highly susceptible to degradation during processing and storage, which limits their application in food systems. However, the role of extraction-derived composition in governing encapsulation performance and stability remains poorly understood. This study investigated how phenolic composition obtained through percolation influences the structural, physicochemical, and thermal properties of maltodextrin-based microcapsules produced by spray drying. High encapsulation efficiency (87%) was achieved; however, compound-dependent losses were observed, including reductions of 43.73% for chlorogenic acid and 52.09% for quercetin under specific storage conditions. Encapsulation improved the retention of volatile compounds and enhanced thermal stability, shifting degradation events to higher temperatures. FTIR analysis revealed intermolecular interactions between phenolic compounds and the carbohydrate matrix, while SEM confirmed the formation of spherical particles typical of spray-dried systems. XRD and thermal analyses indicated predominantly amorphous structures associated with reduced molecular mobility. These results demonstrate that compound retention is governed by molecular structure and matrix interactions rather than apparent antioxidant activity. Overall, this study provides mechanistic insights into structure-mobility-stability relationships and supports the rational design of carbohydrate-based delivery systems for improved bioactive stability.