Abstract: Potato flour was modified by extrusion cooking. The effects of extrusion temperature and water content on the processing characteristics of potato flour and dough elasticity were investigated. The optimum extrusion parameters were determined by one-factor-at-a-time method. Scanning electron microscopy, differential scanning calorimetry, a rapid viscosity analyzer and X-ray diffraction were used to evaluate the structure, thermodynamic properties, gelatinization characteristics and crystallinity of extruded and native potato flour. The results showed that an extrusion temperature of 150 ℃ and a water content of 35% were found to be the optimum conditions to obtain the best processing characteristics, higher solubility, the best water-holding capacity, better freeze-thaw stability and the highest dough elasticity. After extrusion, the surface microstructure of potato flour became wrinkled; the specific surface area increased, while the thermal stability, the gelation capacity and the crystallinity decreased. Extruded potato flour was difficult to retrograde.

Key words: extrusion treatment, potato flour, structure, processing characteristics