Extrusion Pretreated by Steam Conditioning Accompanying Starch Enzymolysis Improved the Dispersibility and Predigestion of Instant Rice Flour
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
To establish preparation technique of instant rice flour with desirable dispersibility and digestive characteristics, the effects of pretreatment of steam conditioning accompanying starch enzymolysis on the dispersibility and predigestion of extrusion-cooked instant rice flour were analyzed in this work. The dispersibility, gelatinization properties and in vitro digestion properties of starch, the contents of soluble protein and reducing sugar were determined in the instant rice flour samples cooked by extrusion with or without pretreatment of steam conditioning accompanying starch enzymolysis. The results showed that compared with simple extrusion, the technology of extrusion pretreated by steam conditioning accompanying starch enzymolysis increased the water solubility index of the instant rice flour by 96.60 %, decreased the water absorption index, agglomerate rate, dispersion time by 72.68%, 51.39%, and 38.27%, respectively, while the viscosity of the rice paste was significantly decreased. The instant rice flour was prepared by the new technology had lower viscosity at low shear rate, and its viscosity curve tended to be straight. Besides, the pretreatment of steam conditioning accompanying starch enzymolysis decreased the angle of repose and slio angle of the rice flour, indicating that the dispersibility and fluidity of the instant rice flour were significantly improved by the technology of extrusion pretreated by steam conditioning accompanying starch enzymolysis. In addition, the brightness and total chroma of instant rice flour prepared by the new technology were significantly lower than those prepared by simple extrusion, resulting in visible chroma difference. The contents of reducing sugar and soluble protein in the instant rice flour were significantly increased after the pretreatment of steam conditioning accompanying starch enzymolysis. Besides, the proportion of rapidly digestible starch was also increased after the pretreatment of steaming conditioning accompanying starch enzymolysis. In conclusion, compared with simple extrusion, the technology of extrusion pretreated by steam conditioning accompanying starch enzymolysis could improve the dispersibility and the predigestion of instant rice flour.
