4D printing of betanin/gelatin/nano-chitin complexes-functionalized surimi via disulfide bonds, and its applicability in dysphagia diets

Betanin/gelatin/nano-chitin complexes were fabricated to functionalize surimi for 4D printing based on the pH responsiveness of betanin, and the application of functionalized surimi was investigated in terms of dysphagia diets. Gelatin and nano-chitin in synergy could protect betanin against heat and UV irradiation by forming hydrogen bonds and electrostatic interactions (CIELab, DSC, XRD, FTIR and TEM). The further functionalized surimi with betanin/gelatin/nano-chitin complexes exhibited low heating loss, heat chromatic aberration, superior thermal stability and compact microstructure (TGA, and SEM). Rheological tests indicated that betanin/gelatin/nano-chitin complexes could reduce the strength of interaction and form new interaction with surimi protein and promoted the surimi to have great shearing-thinning performance, excellent strain deformation resistance, low frequency dependence and great thixotropy. The newly formed interactions were found to be disulfide bonds and hydrophobic interactions and they could further enhance suitable water distribution, and result in a fine and dense network (SDS-PAGE, chemical forces, LF-NMR and AFM). 4D printing of the functionalized surimi demonstrated the excellent color changeable merits (conforming first-order kinetic equation) and color reversibility characteristics along time, and could be also classified as potential dysphagia foods (IDDSI). Hence, surimi functionalized with betanin/gelatin/nano-chitin complexes could effectively realize innovative 4D printing, as well as expand interactive and visual experience of surimi products suitable for various specialized requirements like dysphagia diets.