糙米速食米粥工艺优化及其结构表征

为解决糙米口感差，食用不便等问题，以粳稻糙米和早籼米为原料，采用双螺杆挤压和高温干燥制备糙米速食米粥。在单因素试验基础上，通过Plackett-Burman设计对影响速食米粥的感官评分和复水时间的7个因素进行筛选，确定4个显著因素（淀粉直/支比、复合改良剂用量、物料含水率和干燥温度）。再采用响应面Box-Behnken设计进一步优化4个显著因素，得到优化制备工艺条件为淀粉直/支比 0.26，复合改良剂用量0.65%，物料含水率35.4%，干燥温度 165℃。此工艺条件下，糙米速食米粥感官评分为94分，复水时间为5.3 min。并通过差示扫描量热分析法和扫描电镜对糙米速食米粥的结构表征进行分析，结果表明复合改良剂和淀粉直/支比调配可以提高糊化温度和降低焓变值，使淀粉变得更稳定，更易被糊化；添加复合改良剂和高温干燥能促进粥体孔洞形成，提高其吸水能力，缩短米粥的复水时间。

Processing optimization and structural characterization of instant brown rice porridge

Abstract: In order to solve the problems of bad taste and inconvenient eating of brown rice, this paper used japonica brown rice and early indica rice as raw materials. Instant brown rice porridge was prepared by twin-screw extrusion and high-temperature drying. Because brown rice is a kind of rice grain with only the shell removed and not polished. It retains most of the rice bran layer, germ, and endosperm. It has high nutritional value. However, because the bran layer of brown rice contains bran wax, phytate, and high fiber, brown rice has some problems, such as compact texture, difficulty in cooking, and rough feeling. During the preparation of instant brown rice porridge, seven factors affect the sensory score and rehydration time of the porridge. They are: screw speed, dying temperature, water content, dosage of compound improver, ratio of starch to starch, drying temperature, and drying time. In this paper, the sensory score and rehydration time of instant porridge were optimized by a single factor experiment. On the basis of this experiment, seven factors affecting sensory score and rehydration time of instant brown rice porridge were studied and optimized through Plackett-Burman experimental design in a factorial experiment. Plackett-Burman experimental design is a factorial experiment, which can help to screen out the factors that have a significant influence on the target value from a variety of single factors. Through Plackett-Burman experimental design in the factorial experiment, four factors (starch ratio/branch ratio, compound improver dosage, material water content, and drying temperature) that have a significant influence on the sensory score and rehydration time of instant steamed brown rice were selected from seven factors that affect instant brown rice porridge and then further optimized by the response surface Box-Behnken design. The optimum preparation conditions of instant brown rice porridge were as follows: amylose amylopectin ratio was 0.26, the amount of compound improver was 0.65%, the water content of the material was 35.4%, and the drying temperature was 165°C. Under this condition of instant porridge, the sensory score of the porridge was 94, and the rehydration time was 5.3 min. And the structural characterization of the porridge was analyzed by Differential Scanning Calorimeter (DSC) and Scanning Electron Microscope (SEM). The results showed that compound improver and starch ratio could increase the gelatinization temperature and decrease the enthalpy of the instant brown rice porridge. Increasing the gelatinization temperature of instant brown rice and decreasing the enthalpy change value can make the starch of instant brown rice more stable and easier to gelatinize. In addition, adding compound improver and high-temperature drying can promote the formation of a large number of holes in the granules of the porridge. A large number of holes in the granules of instant brown rice porridge can improve the water absorption capacity of the porridge during rehydration brewing. Therefore, the rehydration time of instant brown rice porridge in the brewing process is shortened.