The Researches On Production Of Glucose From Rice Starch

Rice is the largest agricultural and food variety in China, but for a long time, the processing of rice in China was in a primary stage, which was only met the needs of ration. The effective and comprehensive utilization level of rice source was low. Besides, based on the recent technology in China, there will produce 10-15% broken rice whose price is only 1/3-1/2 to the complete rice during the process, the effective utilization of it is serious deficiency, so it is very important to study the processing technology of rice, so that we can make full use of it. Glucose is one of the most important monosaccharide, and it has been widely used in food, medicine, chemistry and other fields. In this paper, three different types of rice growing widely in China has been used to product glucose, and the preparation technologies of indica glucose and japonica glucose have been optimized, for the purpose of providing theoretical guidance and direction for the comprehensive development and utilization of broken and old rice. The correlations among amylose contents, pasting properties and sugar yields has also been analyzed in this paper, to provide some theoretical basis for the choice of raw materials of sugar production.At the very beginning of this paper, three different types of rice starch (indica starch, japonica starch and glutinous starch) has been extracted by alkali, the glucose preparation technology of indica rice starch and Japonica rice starch has been optimized, and then determined the chemical composition and pasting characteristics of that starches, the correlations among amylose contents, pasting properties and sugar yields has also been analyzed in this paper. The results are as follows:(1) The optimal indica glucose preparation technology has been determined by means of the Single factor and Orthogonal tests. The time of liquefaction is 70 min, liquefaction temperature is 95℃, starch concentration is 25%, the thermostableα-amylase addition level is 25u/g starch, pH value is the nature, and under these conditions, we can get the liquid slurry with the DE value 19.01±0.16%. The optimal saccharification technology is that the temperature is 60℃, pH value 4.0, saccharification time is 48h, glucoamylase use level is 300u/g starch, and the pullulanase dosage is 0.101ASPU/g starch. Under these conditions, the DE value of the saccharified liquid is 99.00±0.83%, whose glucose content is 85.3% determined by HPLC, which means that the conversion rate is high.(2) The optimal Japonica glucose preparation technology has been determined by means of the Single factor and Orthogonal tests. The time of liquefaction is 70 min, liquefaction temperature is 95℃, starch concentration is 25%, the thermostableα-amylase addition level is 25u/g starch, pH value is the nature, and under these conditions, we can get the liquid slurry with the DE value 18.11±0.14%. The optimal saccharification technology is that the temperature is 60℃, pH value is 4.0, saccharification time is 48h, glucoamylase use level is 300u/g starch, and the pullulanase dosage is 0.15ASPU/g starch. Under these conditions, the DE value of the saccharified liquid is 99.28±0.50%, whose glucose content is 88.59% determined by HPLC, which indicates a high conversion rate.(3) The amylose contents of the three different type of rice starch extracted by alkali were significantly different. The indica starch has the highest amylose content (20.28±0.44%), while the glutinous starch has the lowest amylose content (1.24±0.30%), the amylose content of japonica starch is 14.74±0.82%. The degree of difficulty in removing protein vary from the different amylose contents, and because of the high amylopectin content, the glutinous starch has more branch structures which made the structure of glutinous starch looser and the removal of protein easier. As a consequent, the glutinous starch has the lowest final protein content (0.45±0.03%).(4) The pasting properties of the three different rice varieties have been obtained by rapid viscosity analyzer. Glutinous starch has a highest peak viscosity (3098cP), followed by japonica starch (2813cP), indica starch has the lowest one (2356cP). Glutinous starch has the shortest peak viscosity time (3.6min), and japonica starch is 5.27min, while indica starch is 5.53min. By correlation analysis, there is a significant negative correlation between the breakdown value and setback value (γ=-0.933; P<0.01), while there were highly significant positive correlations between amylose content and setback value, peak viscosity time (P<0.01), correlation coefficients y were 0.996 and 0.985. Amylose content and peak viscosity as well as breakdown value were significant negative correlation (p<0.01), the correlation coefficients were-0.931 and -0.906 respectively. (5) By correlation analysis among amylose content, pasting properties and sugar yield, we found that amylose content was significant positively related to the extent of liquefaction and saccharification of rice starch (P<0.01), the correlation coefficients were 0.971 and 0.951 respectively, which means the higher amylose content the starch have the more suitable as a raw material for that starch as a raw material for sugar production. Peak viscosity was significant negative correlated with the extent of liquefaction and saccharification (P<0.01), the correlation coefficients were -0.823 and -0.777, which indicates that the higher value the peak viscosity of the starch have the more unsuitable for that starch as a row material for sugar production.