| Rice strach, one of important cereal starch and amount of rice starch is as high as 80% in rice, is the main ingredients. Rice starch has some unique properties, such as small granules, low-allergic and other, so it has been extensively used in many fields and has a good market prospects. At present, there is great demand for high-grade rice starch (the protein content of less than 0.5%) in the international market.There are many methords of preparation rice starch according to the affluent rice resources, this test is aim at obtaining the drug-level rice starch, and describes the extraction of starch and protein from rice flour with alkali methord(NaOH). The alkali methord has several advantages compared with other methords, such as higher extraction rate, lower cost and suitable for industrial production.But in the alkali process, there had been as following issues: that is the low yield and low purity of rice starch. The extraction method of rice starch was improved with alkali method (NaOH) in this paper. On the basis of the existing technics, the first alkali seperation of rice and the again-purification of yellow starch were combined to obtain a new isolation technic, which could improve the purity and the yield of the product. The effects of time, material-liquid ratio, an amount of NaOH and temperature on the purity and yield of the product were analyzed, and the conditions of the extraction were optimized by Orthogonal Experiment. The results showed the purity of the product is as high as 99.17% (dry basis) with the total yield of 72.7%, which is higher than the literature value of 47.87%.The modified rice starch has been applied widely also in some special industry. Porous starch, which has good adsorption properties and can reach 215 -413 times of rice starch as adsorption of functional material, is one of the modified rice starch. So in the practice of all aspects of production, there has been a wide range of applications for the porous starch.On the basis of the seperation of rice starch by alkali methord, an advantageous way to produce porous starch was investigated and the technology conditions of porous rice starch by enzymolysis were studied in this paper. In the enzymolysis process, the mixed enzymes glucoamylase andα-amylase was used to produce porous starch, and six factores were investigated, that is the ratio of enzyma, reaction time, temperature, systerm pH, quantity of enzymes and solid concentration. The conditions of the complex enzymes acting on the raw rice starch were optimized by both the single-factor mothed and the orthogonal experiment mothed. The obtained optimal technollogical conditions of enzymolysis are temperature 50℃, reaction time 12h, systerm pH 4.6, ratio ofα-amylase and glucoamylase 1:12, quantity of enzymes 0.5%, solid concentration25%. And the analytical methods was improved, a qualitative and quantitative analysis method was established for porous starch in this paper. The absorbent ability of water and oil is 125.8% and 163.2% for porous starch, respectively. And the specific surface area is 2.219m~2/g. It apply an important act on the comprehensive development of domestic rice and starch resources, and to provide reference data for promoting industrialized production of porous starch. |
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