Structural, rheological, and physicochemical properties of starch-based eutectogels from diverse botanical sources

Deep eutectic solvents (DES) have emerged as green alternatives for starch modification, yet understanding of how native starch structure determines modification outcomes remains limited. This study elucidates the relationship between native starch type and DES treatment outcomes through characterization of eutectogels prepared from ten botanically diverse starches using fructose-malic acid natural DES (NADES). The acidic NADES promoted degradation of long-chain amylose and enhanced granule dissolution, leading to reduced gel network strength in eutectogels compared to hydrogels, with extents varying among starch types. Fourier-transform infrared spectroscopy showed reduced short-range ordered structures together with enhanced crystalline structures after NADES treatment. Thermal analysis indicated higher gelatinization temperatures for eutectogels. These molecular-level modifications were reflected by functional property changes that differed by starch category. Rheological and texture analyses showed that most eutectogels developed weaker gel networks with more fluid-like behavior, particularly those from root/tuber and cereal starches, whereas legume starch eutectogels exhibited greater shear resistance and reduced syneresis. Syneresis increased in most eutectogels except those from legume starches. Principal component analysis showed that amylose content, granule size, and crystalline structure governed NADES response patterns. These findings expand understanding of starch-NADES interactions and highlight the role of native structure in tailoring starch-based materials.