Dual cross-linked starch hydrogel for eugenol encapsulation and the formation of hydrogen bonds on textural hydrogel

Physical and chemical cross-linked hydrogels combining N, N'-Methylenebisacrylamide (MBA)-grafted starch (MBAS) and sorbitol were successfully prepared and encapsulated with eugenol in this work. The dense porous structure with diameter of 10-15 μm and strong skeleton after restructuring inside the hydrogel was confirmed by SEM. The band shifts between 3258 cm^-1 and 3264 cm^-1 clarified the presence of a large number of hydrogen bonds in physical and chemical cross-linked hydrogels. The robust structure of the hydrogel was confirmed by mechanical and thermal property measurements. Molecular docking techniques were used to help understand the bridging pattern between three raw materials and to assess the advantageous conformation, which demonstrate sorbitol is beneficial to improve the characteristics of textural hydrogel by the formation of hydrogen bonds, creating a denser network, structural recombination and new intermolecular hydrogen bonds between starch and sorbitol afforded considerably junction zones. Compared to ordinary starch-based hydrogels, eugenol-loaded starch-sorbitol hydrogels (ESSG) exhibited a more attractive internal structure, swelling properties, viscoelasticity. Moreover, the ESSG showed excellent antimicrobial activity for typical undesired microorganisms in foods.