The Research Of Japonica Quality Indicators,Volatile Substances And Moisture Migration Variation During Storage

Under the condition of different storage,this article mainly studies the quality indicators,smell and the change on moisture data collected in the low field nuclear magnetic resonance of japonica rice.And the moisture contents of japonica rice newly collected in 2013 are adjusted to 13.5%,14.5%.15.5% and 16.5%,respectively.Next,put them in the sealed bags and decompress and fill the nitrogen.Adjust the concentration of oxygen to 2%,5%,8% and 21%,respectively.After that,put them into the artificial climate boxes at the temperature of 15?,20?,25? and 30?,respectively for 30 days stimulated storage.The fatty acid value,color difference,texture,PPO and many other indicators should be measured in every 30 days.At the same time,the volatile materials and the changes on moisture data collected in the low field nuclear magnetic resonance should be measured by electronic nose and GC-MS.The following conclusions of the experiment was drawn through the above three factors,four levels and all factors.1.The storage conditions,such as time,temperature,the oxygen concentration,and the moisture content have great effects on the quality of japonica rice.As time goes on,the quality of japonica rice will go bad.And if the temperature and the moisture content are too high,the quality of japonica rice also will deteriorate quickly.However,when the temperature and moisture are high and the oxygen concentration is low,it will be easy to control the speed of the deterioration of japonica rice.It is benificial to store the japonica rice under low temperature and low oxygen concentration condition,while the economic cost will be high.Therefore,the proper storage condition is needed,and the corresponded measurement should be taken according to the change on the quality of japonica rice,so that the storage period can be extended and the number and quality of rice can be ensured.2.The major components of japonica rice with the 14.5% moisture content can be analyzed after measuring by electronic nose.The contribution rate of first main component?PC1?is 98.374%;the contribution rate of second main component?PC2?is 1.414%;and there are 96 kinds of volatile substances of japonica rice through the measuring of GC-MS under the storage condition of 14.5% moisture content.The principle components of japonica rice under the storage condition of 16.5% moisture content after measuring by electronic nose can be obtained as follow.The contribution rate of first main component?PC1?is 97.653%;the contribution rate of second main component?PC2?is 1.349%;and 167 kinds of volatile substances of japonica rice were found through GC-MS measurement.3.The japonica rice contains adsorption water,free water,fat,etc.And the adsorption water of japonica rice will be affected by temperature,initial moisture content and the storage time greatly.Japonica rice with different moisture contents have a relatively stable peak values in diverse inversion peaks.However,with the increasing of moisture content,the time of peak value rises slightly,and the degree of freedom in japonica rice water protons raises as well.4.The moisture content of japonica rice has a significant relationship with the areas of inversion peak T₂₁ and T₂₂ in low field nuclear magnetic.The acreage of peak T23 decreases constantly when the moisture contents of japonica rice increasing,The MRI image of japonica rice collected by low field nuclear magnetic can reflect the inner proton status of japonica rice and the intensity of proton.The inner moisture of japonica rice with low moisture content mainly exist in the embryo and back,while the inner moisture of japonica rice with high moisture content distributes relatively uniform.5.The hardness and adhesion of japonica rice have a linear relationship with T₂₁ peak time during the storage.And the relative errors between model predicted value of hardness and adhesion and the measured value are between 0.4 and 0.6%,which indicates that these models can predict the variation of hardness and adhesion of japonica rice during storage.