Abstract: In an attempt to explore the effect of protein on starch properties, we measured the pasting, rheological and textural properties and microstructure of buckwheat starch added with different proportions of mung bean protein utilizing a rapid visco analyzer, a rheometer and a texture analyzer. The results showed that the pasting time and temperature of buckwheat starch were increased while peak viscosity, final viscosity, breakdown value and setback value were reduced by adding mung bean protein. As the addition of mung bean protein increased, shear stress and consistency coefficient K declined while the starch paste was still a pseudoplastic fluid. An 8:2 ratio of mung bean protein to buckwheat starch showed more significant shear thinning. Both storage modulus (G’) and loss modulus (G”) were reduced, loss angle tangent (tanδ) was increased and gel strength was weakened by the addition of mung bean protein. Moreover, the hardness, gumminess and chewiness of the starch gel were significantly decreased and the elasticity became slightly lower. As observed by scanning electron microscopy (SEM), the starch gel showed a honeycomb-like microstructure with the pores becoming larger and the cell wall becoming thinner with increasing addition of mung bean protein.

Key words: gel; pasting properties; rheological properties; texture properties; microstructure