Promoted strain-hardening and crystallinity of a soy protein-konjac glucomannan complex gel by konjac glucomannan

Protein-polysaccharide composite plays a substantial part in manufacturing plant-based meat and seafood alternatives. This research examined the impact of konjac glucomannan (KGM) concentrations on the molecular interactivities, gelation behaviors, and viscoelastic properties of a soy protein − konjac glucomannan complex gel, which was used as a model system for a plant-based fishball analog. The results revealed that increasing KGM concentration promoted the strain-hardening phenomenon of the complex gel, indicating an enhanced excluded volume interaction and the existence of large junction zones within the gel network. Additionally, increasing KGM level could extend the protein denaturation, exposing more buried functional groups, facilitating subsequent protein aggregation. Furthermore, as KGM rose from 0 to 8.0%, the gel strength Sg of the complex gel improved remarkably from 82.5 to 5537.6 Pa∙sn; contrastingly, the relaxation exponent n declined significantly from 0.72 to 0.12, revealing that KGM could facilitate the transition from sol to a more closely pure elastic solid. Interestingly, with the increased KGM incorporation, the relative crystalline index of the complex gel augmented from 26.79% to 53.08%, encouraging the construction of a regulated and compact gel network. Microstructure observations further supported that KGM induced a close-packed complex gel network with profound aggregations and large junctions. This study contributed to the further understanding of molecular interactivities between protein and KGM, providing fundamental support for the potential application of the KGM-protein complex in plant-based seafood alternatives.