Effects of konjac glucomannan on physical properties and microstructure of fish myofibrillar protein gel: Phase behaviours involved

Hidden phase behaviours in gel systems are essential factors that affect the viscoelasticity and other physical properties of blended gels; however, data on the internal phase behaviour of proteins and polysaccharides in surimi gel systems are lacking. This study establishes a relationship between dynamic rheology and the phase behaviours of protein/polysaccharide-blended systems using myofibrillar protein (MP) extracted from surimi and konjac glucomannan (KGM) as a model. The rheological parameters of this blended system with different KGM contents were analysed. We defined the phase behaviour index as the ratio of αG′ to αG″ explained by a nonlinear oscillating deformation test. The ratios of the rheological values of the MP/KGM blended system and those of the linear summation of the MP and KGM samples, αG′ and αG″, were linked to phase behaviours. We further verified this conjecture via confocal scanning laser microscopy, atomic force microscopy and fractal dimension. This novel approach will not only facilitate the evaluation of internal phase behaviours in blended systems but also optimize future rheology experiments and ingredients to improve the physicochemical properties of compound food.