Study On The Process Optimization And Storage Stability Of Extruded Rice

Rice is one of the most important crops in the word, and our country is the largest producer of rice. But we can’t make full use of the by-product in the process of rice, such as broken rice and so on. The nutrients in the broken rice is basically the same with rice, and the main component of rice is75%starch and8%protein. The PER of broken rice is2and it’s nutritional quality is good, but the price of broken rice is lower than rice. This paper studied the optimization of extruded rice in order to make full use of cardamine resources in our country and improve it’s economic value. The broken rice were used as raw material in this paper, according to the response surface experiment design, the production process of extruded rice was optimized, some of the basic characteristics and storage characteristics of extruded rice were studied too, the results were as follows:(1) On the basis of the single-factor test, according to the Box-Behnken center-united experimental design principle, the production parameters of extruded rice were optimized with the method of response surface analysis by3factors,3levels, and the score of texture and water absorption was used as the target. The best production parameters of extruded rice were:temperature90℃, water25%, screw speed180r/min.(2) The microstructure、textural properties and the taste of extruded rice were studied. According to the results of election microscopy, the starch granules in extruded rice could not be seen, but these could be seen clearly in rice. Because of the high temperature、high pressure and high shear stress in extruder, the starch in rice were gelatinized, the texture of extruded rice became the same,so we could not see the starch. The results of texture test showed that the hardness and chewiness of extruded rice were lower than rice, but the adhesiveness and springiness were higher than rice. The results of eating quality showed that extruded rice were not easy to be accepted by people and the sensory scores were low, because the adding of nutrients make color and taste changed. When the extruded rice mixed with rice in a1:100ratio, its sensory scores was improved and could be accepted easily. (3)During storage period, the quality difference between extruded rice and rice were studied by determining the nutrient contend textural properties、fatty acid value and water absorption and so on. The results showed that Fe and Zn were mostly lost. After storage of90days, the average loss rate of Fe was about66.87%and Zn was77.65%. the other nutrients were more stable; both of the two kinds of rice had varying degrees of aging during storage, such as hardness increased、adhesiveness reduced、springiness reduced, chewiness improved, fatty acid value rose、water absorption reduced and so on, but the aging speed of extruded rice was lower than rice.