Optimization of Preparation Process and Properties Study of Japonica Recombinant Rice

The recombinant rice was prepared by twin-screw extrusion with broken japonica rice flour as raw material and a certain amount of resistant japonica rice starch. The study investigated the effects of die temperature, moisture content and screw speed on the quality of the recombinant rice. On the basis of single factor, the extrusion process conditions were optimized by response surface methodology. The pasting, rheological, cooking, and digestive properties of the recombinant rice were subsequently determined. The findings indicated that a composite score of 70.7±0.5 of recombinant rice was achieved at a die temperature of 100 ℃, moisture content of 28%, and screw speed of 96 r/min. The pasting properties indexes of recombinant rice were less than commercially available japonica rice, but slightly higher than blank recombinant rice, considering viscosity, retention value, and pasting temperature. The G' and G" of the recombinant rice were lower than those of commercially available japonica rice but slightly higher than those of the blank recombinant rice. Recombinant rice had higher water absorption, volume expansion, and cooking loss than blank recombinant rice and commercially available japonica rice. The recombinant rice had higher SDS and RS contents and lower RDS contents compared to the blank recombinant rice and commercially available japonica rice, which were respectively 51.62%, 9.37%, and 39.01%. The study results may serve as an experimental foundation for the creation of low-digestible recombinant rice products.