Abstract: Three sweet potato residue cellulose (SPRC) powders with different particle sizes (129, 64, and 25 μm) were obtained by ordinary pulverization, ultra fine pulverization and nano-ball milling, respectively. Each of them was separately added at 7% to wheat flour in order to determine their effects on the rheological properties of wheat dough. The results showed that SPRC increased the water absorption rate of dough, prolonged the dough formation time, and reduced the dough stability time, maximum viscosity index, thermal gel stability, retrogradation value and gelatinization value. In addition, SPRC increased the viscoelasticity of dough. Temperature had a great influence on the elastic modulus (G’) of the mixed dough, but had no significant influence on the viscous modulus (G’’). Scanning electron microscopy showed that the gluten network structure in dough incorporated with large-particle-size SPRC exhibited rupture and holes, but reducing the particle size of SPRC improved its density uniformity. Compared with ordinary pulverization and ultra fine pulverization, nano-ball milling SPRC enhanced the farinographic properties and thermomechanical properties of dough. Accordingly, the particle size of SPRC had a significant impact on the rheological properties of wheat dough. Reasonable control of the particle size of added dietary fiber in wheat flour can be useful to improve dough quality.

Key words: sweet potato residue cellulose; particle size; dough rheological properties; microstructure