| China is the largest rice producing country in the world.The annual output of rice was 1.8-2 million tons. For a long time,China's rice is still in the primary processing state of process.The process will generate 10%-15% the broken-rice, which were used primarily as feed ingredients, but failed to obtain the efficient development of value-added processing. Basic component of broken-rice nearly is equal to rice, rich in starch, protein and other nutrients, but the price is only 1/3-1/2 of rice. It results in a significant waste of resources of rice,so research and development of deep-processed products become more and more urgent.Sorbitol is an important chemical and pharmaceutical raw materials, widely used in pharmaceutical industry, food, cosmetics and other industries.The paper used broken-rice as raw material,and did the research of preparation of sorbitol production process, in order to provide a new way for the comprehensive development and utilization of broken-rice.First of all, the process of liquefaction and saccharification by dual-enzymem method were studied. and then two methods(bio-fermentation and hydrogenation) were used to produce sorbitol from glucose, and the quality of sorbitol which was produced by hydrogenation method was measured and the bread experimental application was made. The major ruslts were as follows:(1)The optimal parameters of liquefaction were:90℃for liquefaction, natural pH,15u/g of thermostable a-amylase,6:1 of material-liquid ratio, and 15-20 min of liquefaction. Under this optimal condition,DE value of liquefaction was 17.3%. Similarly, the saccharification parameters were optimized to be 60℃for saccharification,24h of saccharification time,80u/g of glucoamylase and pH 3.5 through orthogonal test. The final DE value of saccharification reached up to 99.5% under this optimal condition. The quality of glucose solution produced under the optimal conditions are as follows, light yellow, odorless, sweet and mild, pH 2.55, light transmission rate 3.5%.Viscosity at 30℃reached the maximum 1610mpa·s. The glucose content in syrup was 77.3% through HPLC.(2) The optimal parameters of preparation of sorbitol by hydrogenation were: 10Mpa for reaction pressure,120℃for reaction temperature,2h of reaction time, pH8,5% of the amount of catalyst and 200r/min of speed.Under these conditions, the ratio of broken-rice glucose to sorbitol reached 40.34%. (3)The optimal parameters of the culture of Zymomonas mobilis were:(NH4)2SO4 for the source of nitrogen,5% of volume of inoculation,30℃for temperature,100rpm of speed and 7.0 of initial pH value. Similarly, the fermentation parameters were optimized to be 2% of volume of inoculation,35℃for fermentation temperature, 100rpm of speed,7.0 of initial pH value,25% of the concentration of glucose.Under these conditions,the final concentration of sorbitol reached 2.153g/L.(4) The related characteristics of sorbitol by hydrogenation were analyzed and compared with the characteristics of standard sorbitol.The results showed the transmittance rate of product was 96.0%,the rate of standard was 99.7%.Under the condition,the moisture absorption rate of product was 0.86%,the moisture absorption rate of standard was 1.05%. The color difference index of product was L=91.36,a=-0.74,b=10.34.It indicated that compared with standard goods,products were a little brighter, slightly green, slightly yellow. The measured results showed that the quality of products are slightly lower than the standard sorbitol.(5)The bread experimental application was made.Bread which the sweetener was sorbitol was compared with the bread which the sweetener was sucrose.The results were as follows:the properties of two kinds of bread were almost the same, the bread skin color, smoothness, texture, structure,shells and other indexs were almost the same.Only the taste(sweetness)of former is slightly lower than the taste of the latter. It indicated that sorbitol can be used as a sweetener to substitute sugar in bread production.
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