Simultaneous Determination Of The Main Ingredient Content In Grain By Thermogravimetric Analysis

Thermal analysis is a technology to study physical and chemical changes of the matter by heat or cool process,its advantage are less sample consumption,rapid analysis,easy preparation,high sensitivity and so on.It has been applied widely to physical,chemistry,chemical engineer,petroleum,building materials,biochemical,polymer and food industry.Common thermal analysis methods are thermogravimetry,differential scanning calorimetry,differential thermal analysis.This paper aims to establish a new method to determination the main components content in grain at the same time.By thermal analysis,the characteristic decomposition temperature of moisture,starch,protein and fat in soybean were Tmoisture?150oC,180??Tstarch?270?,270 oC?Tprotein?350?and 330??Tfat?460? respectively.The experimental conditions were optimized: the atmosphere was argon,the sample size was 40 mesh,the amount of sample was 10 mg,the heating rate was 10oC/min.The correlation equations were founded by national standard method and the DTG peak under optimum conditions,they are respectively: y =0.05649x-0.13485,r = 0.8088 for the moisture,y = 0.0319x-0.22977,r = 0.9817 for the starch,y = 0.00067 x +0.6486,r = 0.8447 for the protein and y = 0.05973x-0.75639,r = 0.9071 for the fat.The measurement error is small and the result is satisfactory.The result shows that the DTG method is suitable for simultaneous determination of moisture,starch,crude protein and crude fat in soybean samples.By thermal analysis,the characteristic decomposition temperature of moisture,starch,protein in wheat were measured in wheat samples,as follows:Tmoisture?130?;150??Tstarch?250?;250??Tprotein?350?.In optimized conditions,the contents of water,starch and protein were determined by national standard method and the peak area of DTG were determine by derivative thermogravimetric method in 20 wheatsamples.The correlation coefficients as follows: y = 0.0469 X = 0.1887,r = 0.9888 for moisture,y = 0.0053 x + 0.5697,r = 0.9812 for starch,y = 0.0327x-0.0437,r = 0.9852 for protein.Then verified results show that the error of water has little effect,and the error of starch and crude protein have a great influence.This method is only applicable to the rough determination of main components in wheat.By thermogravimetric analysis,the characteristic decomposition temperature of moisture,starch,protein were measured in mung bean.As follows:Tmoisture?130?;130??Tstarch?250?;250??Tprotein?330?.The contents of water,starch,protein and their DTG peak area were determined respectively by GB and DTG methods in the optimization conditions.The correlation equations were obtained as follows: y = 0.0301x-0.0112,r = 0.9845;y = 0.0098 x + 0.1534,r = 0.9912;y = 0.0312x-0.2224,r = 0.9755.And the linear equation is verified and the result error is allowed.The DTG method is suitable to determine the content of water,starch and crude protein in the mung bean sample.