Structural and physicochemical properties of hydrothermally treated starch microparticle (SMP)

This study investigated the effects of hydrothermal treatments on the structural and physicochemical properties of starch microparticles (SMP) to enhance their functionality. SMP was treated by heat moisture treatment (HMT; 90℃, 30% moisture) and annealing (ANN; 50℃, 70% moisture). HMT induced surface melting, particle agglomeration, and increased water holding capacity, whereas ANN produced denser and more uniform particles with improved dispersion stability. All samples retained B-type crystallinity, although relative crystallinity decreased from 11.47 to 8.50% after HMT, indicating disruption of double helices. Thermal analysis showed narrowed melting ranges and increased onset temperatures, with decreased melting enthalpy in HMT-SMP and increased enthalpy in ANN-SMP. In vitro digestibility revealed reduced enzymatic accessibility and elevated resistant starch content in HMT-SMP (~ 55.99%). These findings indicate that HMT promotes helix disruption and aggregation, while ANN enhances molecular rearrangement in SMP. Overall, hydrothermal processing is an effective post-processing strategy for tailoring SMP functionality.