The structural, thermal, and nutritional characteristics of embedded corn starch after gelatinization and digestive
Wenjuan Feng1, Xiao Zhou1, Bo Pan2
1State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, China.
Background:
Understanding starch behavior under various processing conditions is important for the development of novel food products with tailored nutritional profiles. This study investigated changes to the structure and properties of native corn starch (NCS) and biomimetic starch-entrapped microspheres following thermal and enzymatic treatments.
Results:
Heat-treated microspheres showed more birefringence and structural order than native starch, indicating incomplete gelatinization due to the alginate matrix. Microspheres (MC-1 and MC-2) exhibited lower pasting viscosities. Larger particles retarded viscosity development. Enzyme kinetics showed higher apparent maximum reaction velocity (Vm) but an increased Michaelis constant (Km) for microspheres in comparison with native starch. The elevated Km reflects reduced enzyme affinity due to the alginate barrier, and the higher Vm results from transiently high local substrate concentration on the surface. Digestion progressed from the outer layer toward the core, with MC-2 retaining higher crystallinity and structural integrity after 120 min because of the protective effect of the alginate matrix. Thermal analysis demonstrated that gelatinization onset (Tₒ), peak (Tp), and conclusion (Tc) temperatures increased with digestion time in all samples and the enthalpy change (ΔH) decreased, consistent with structural reordering after digestion. The alginate shell in microspheres effectively delayed amorphous region hydrolysis, enhancing thermal stability. Consequently, the rapidly digestible starch (RDS) content decreased from 84.54% in NCS to 47.06% in MC-2, whereas the resistant starch (RS) and slowly digestible starch (SDS) content increased from 20.42% to 44.21% and from 7.90% to 34.90%, respectively.
Conclusion:
Alginate encapsulation enhanced the thermal properties of starch and increased its slowly digestible and resistant starch content by forming biomimetic starch-entrapped microspheres. © 2025 Society of Chemical Industry.
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