Effects of glutenin and gliadin modified by protein-glutaminase on pasting, rheological properties and microstructure of potato starch

Glutenin and gliadin were treated with protein-glutaminase in order to obtain soluble glutenin (PG-Glu) and gliadin (PG-Gli). PG-Glu or PG-Gli was added to potato starch at various concentrations (0.5%, 1.0%, and 1.5% of starch weight, w/w), and the physicochemical properties and microstructure of starch/protein mixtures were investigated. The results showed that the presence of PG-Glu or PG-Gli decreased the viscosity parameters and yield stress and consistency coefficient of mixed pastes. The starch/protein mixed pastes exhibited a pseudoplastic and shear-thinning behavior under yield stress condition, and the storage modulus and loss modulus increased. Moreover, the To, Tp, Tc, and ΔH of starch/protein mixtures varied insignificantly compared with native starch. CLSM results confirmed the inhibition of PG-Glu and PG-Gli on the gelatinization of starch, and the morphology of starch granules became more compact. These results suggest that the physicochemical properties and microstructure of potato starch are effectively influenced by PG-Glu or PG-Gli.