挤压方便米的径向膨胀率与其复水率、糊化度关系的研究

Studies of Relationship between Radial Expansion Ratio and Rehydration Ratio/Gelatinization Degree of Extruded Instant Rice

以早籼米为原料,采用双螺杆挤压技术,研究大米挤出物的径向膨胀率和复水率随挤压加工参数变化规律,同时研究膨胀率与挤压方便米饭复水率、糊化度的关系,以期为挤压方便米饭的生产摸索出方便有效的生产标准。实验表明,不同挤压条件下,径向膨胀率皆和复水率有相同变化趋势,复水率、糊化度亦随膨胀率的变化呈相同变化趋势。研究结果表明,当原料水分32%,进料速度70g/min,螺杆转速150r/min,末端机筒温度92℃的情况下,物料径向膨胀率达到2.19,糊化度达到87.8%,产品色泽接近天然大米,内部具有致密多孔的结构,5min内的复水率达到2.03,复水之后,复水20min之内产品外形保持良好。

In order to find out the effective producing standard for extruded instant rice products,regularity of radial expansion ratio of rice extrudates changing with extrusion parameters was studied by using a twin-screw extruder and indica rice as raw material.And the relationship between radial expansion ratio and rehydration ratio/gelatinization ratio were also studied.It was found that both rehydration ratio and radial expansion ratio had similar trend under different extrusion cooking conditions.Also,within a certain range of radial expansion ratio,both rehydration ratio and gelatinization degree had similar trend.Under the conditions of water content 32%,feeding rate 70g/min,screw rotating speed 150 rpm,terminal barrel temperature 92 °C,the radial expansion ratio and gelatinization degree reached 2.19 and 87.8%,respectively.SEM observation showed a dense and porous structure in the inner of the product and the color values were similar with those of the natural indica rice.The rehydration ratio within 5 minutes reached 2.03,and the shape of the rehydrated product had been kept well within 20 minutes.