| Corn flour is rich in nutritional value, but the taste is rough, it can not form the dough possessed viscoelastic and extensibility, because of its unique composition and molecular structure of starch and protein. The poor in processing limited the application of corn flour in food processing. In order to improve the food quality and processing quality of ordinary corn flour, with ordinary corn flour as raw material, the physical and chemical properties and pasting characteristic curves of corn flour that was texture and structure recombined by ultra-high pressure(UHP) technology or twin-screw extrusion technology were studied, the optimal recombination processing parameters of corn flour were determined. The dumplings were developed with texture and structure recombination corn flour as raw material. The optimal ratio of dumplings flour was determined by comparative analyzing that contains instrumental analysis and sensory evaluation of different ratio of dumplings flour. The main contents and results were as follows:1. The ordinary corn flour was texture and structure recombined by UHP technology. The results showed that gelatinization temperature of corn flour increased with the increment of pressure, gelatinization temperature enhanced firstly and then decreased with the prolongation of holding time and cold viscosity stability were improved, and the effect of the concentration of corn flour was not significant. The water solubility index (WSI) and water absorption index (WAI) of corn flour increased with the increment of pressure, the WSI and WAI enhanced firstly and then decreased with the prolongation of holding time and the increment of the concentration of corn flour. The gelatinization degree of corn flour increased with the increment of pressure and the prolongation of holding time, the gelatinization degree of corn flour enhanced firstly and then decreased with the increment of the concentration of corn flour. The results of correlation analysis showed that there was a certain correlation between gelatinization degree of corn flour and UHP processing parameters (pressure, holding time and the concentration of corn flour), WSI, WAI and freeze-thaw stability. The results of orthogonal experiment showed that the corn flour which concentration is 15% was gelatinized 98.66% under pressure of 500Mpa for 20min.2. The ordinary corn flour was texture and structure recombined by twin-screw extrusion technology. The results showed that the cold extrusion index and extrusion index of corn flour enhanced firstly and then decreased with the increment of barrel temperature and the acceleration of screw speed, the cold extrusion index decreased with the increment of moisture, but the extrusion index increased. As the barrel temperature, screw speed increased, the expansion ratio of samples was reduced, and the effect of moisture was not significant. The water solubility index (WSI) increased with the increment of barrel temperature and screw speed, but the water absorption index (WAI) decreased. The WAI decreased with the increment of moisture but the WSI increased. The gelatinization degree of corn flour increased with the increment of barrel temperature and screw speed and decreased with the increment of moisture. The results of correlation showed that there was a certain correlation between gelatinization degree of corn flour and twin-screw extrusion processing parameters (barrel temperature, screw speed and moisture of corn flour), expansion ratio, water solubility index and water absorption index. The results of RSM experiment showed that the corn flour whose moisture is 15% was gelatinized 95.18% under twin-screw extrusion processing of barrel temperature 170℃and screw speed 31 Hz.3. The optimal ratio of corn flour used to make dumplings was obtained by the experiment. When the optimal ratio of flour texture and structure recombined by UHP technology and wheat flour was 65:35, the power of dumpling skins worn was 960.27g·s, the springiness was 0.81, the cohesiveness was 0.67, the chewiness was 2491.25. When the optimal ratio of flour texture and structure recombined by twin-screw extrusion technology and ordinary corn flour was 55:45, the power of dumplings skins was2261.93g·s, the springiness was 0.78, the cohesiveness was 0.62, the chewiness was 1544.33.The dumplings produced by flour recombined by UHP and twin-screw extrusion technology with a unique color of corn flour, tasted smooth, well and pucker.The results of above research showed that the quality of ordinary corn flour were significantly improved by texture and structure recombination by UHP and twin-screw extrusion technology, the springiness, cohesiveness and chewiness of corn flour were significantly improved by the texture and structure recombination by twin-screw extrusion technology and reached to the effect of wheat flour. Ultra-high pressure technology and twin-screw extrusion technology can be used as effective methods to improve the food quality and processing quality of ordinary corn flour.
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