Synergistic effects of konjac glucomannan and ultrasound treatment on inhibiting retrogradation and modifying structural properties of quinoa starch gels

Konjac glucomannan enhances starch gel quality and freeze–thaw stability. • Ultrasound produces firmer starch gels while effectively delaying staling process. • Konjac glucomannan and ultrasound synergistically optimize starch molecular structure. • Konjac glucomannan and ultrasound inhibit molecular reassociation. • The synergistic treatment effectively retards the starch retrogradation process. This study investigated the effects of konjac glucomannan (KGM) and ultrasound treatment on the transparency, retrogradation, freeze–thaw stability, thermal behavior, and structural characteristics of quinoa starch. Results revealed that the ultrasound–KGM treatment significantly enhanced the resistance of quinoa starch to retrogradation. Specifically, compared with ultrasound treatment alone, the combined treatment increased starch transparency by 0.31% and gel hardness by 12.16%. Microstructural analysis revealed the formation of a more continuous and compact starch network under the combined treatment. X–ray diffraction spectroscopy and Fourier transform infrared spectroscopy revealed increased relative crystallinity and a higher absorbance ratio at 1047/1022 cm −1 , indicating enhanced short–range molecular order and changes in the multi–scale structure of quinoa starch. These findings suggest that ultrasound–KGM treatment effectively delays the retrogradation of quinoa starch and improves its functional properties, offering a theoretical basis for the broader application of this combined treatment in starch–based food systems.