Abstract:
Superheated steam treatment is an emerging green heat treatment technology, however, its impacts on the physicochemical characteristics of rice flour and the quality of instant rice noodles flour have not been explored. To explore the quality change of rice noodles prepared by superheated steam raw materials, rice was superheated by steam at different temperatures (120, 150, and 180 ℃) for different timelengths (0, 2, 4, 6, and 8 min). Then, superheated rice was crushed into rice flour, and after humidity was adjusted to 33%, rice noodles were prepared by squeezing and dried at room temperature for 24 h. The basic components of the processed rice were determined, the color and luster of the rice noodles were determined after lyophilization and crushing. The rehydration time, break rate, cooking characteristics and texture characteristics were determined after the rice noodles were dried at room temperature. Rice noodles were sensory scored by 12 professionally trained members. The results showed that: (1) Within the treatment range of 120 ℃, 2 min to 180 ℃, 8 min, the superheated steam treatment did not change the brightness and whiteness of the rice noodles, and no significant change of the overall color was determined. (2) The rehydration time and break rate of the rice noodles were significantly reduced under the treatment time of 2 min, and the break rate increased with the increase of temperature. The rehydration time of the rice noodles was reduced to the minimum at 150 ℃ and 4 min, 450 s, which was reduced by about 10%. The break rate was the smallest at 120 ℃ and 2 min, which was 3. 33%, followed by 4 to 6 min. With the increase of treatment time and temperature, the water absorption rate of the rice nooldes increased as a whole. (3) The hardness of the rice noodles increased first and then decreased with the extension of the processing time, reaching the maximum value at 4 or 6 min. The adhesion decreased with the increase of the treatment strength, in contrast, the tensile strength and the fracture distance of the rice noodles increased. However, high temperature and long-term treatment reduced the maximum tensile strength and tensile breaking distance. (4) Superheated steam treatment affected the sensory quality of rice noodles, in detail, tissue morphology, paste soup direction, hardness and viscosity scores of convenient rice noodles increased. However, under extreme treatment conditions, quality was not improved, and even the tissue morphology and pasting properties were deteriorated. On the whole, under the condition of 150 ℃ and short processing time, the sensory quality of instant rice noodles was the best.