Setting Up Of Guideline For Evaluation Of Brown Rice Storage Character

In order to study the mechanism of brown rice aging and set up a quick and accuratemethod to identify the degree of brown rice aging, the final aim is to set up the guideline forevaluation of brown rice storage character. Two Japonica brown rice (liaoxing and yanfeng)was selected to do the experiments, the storage conditions is15℃,75%（low-temperaturestorage）,20℃,75%（quasi-low temperature storage）,25℃,75%（room-temperature storage）,35℃，75%（high-temperature storage）and room temperature storage. The storage period is300days, sampling once every30days, and observing the change of free-fatty acid, fallingnumber，reducing sugar content, germination-rate, viability, electrical conductivity, PPO,POD and MDA content during brown rice storage. The correlations and differences amongthese indexes and with the storage time or storage temperate were studied, the most sensitiveindex was selected and set up an aging mathematical model, the result are:(1) The two Japonica brown rice didn’t have bran until storied for300d under15℃and20℃conditions, but the brown rice under35℃and room temperate with serious bran causing,and the time arousing bran is earlier than the other conditions. The L*value of the two typesof brown rice is unchanged at start then sharply reduced, a*value unchanged at start thensharply increased, b*value is increasing all the time. The smell of the two types of brown ricedidn’t change during300d period under the conditions of15℃and20℃, but at hightemperate condition the smell changed quickly.(2) The germination-rate and viability of the brown rice falling all the time, free-fattyacid and falling number are increasing with the storage time, while the electrical conductivityis increased at first then decreased, reducing sugar content, PPO and POD are increased atfirst then decreased. After the analysis of the correlations and differences among these indexessaying that, moisture content, germination-rate, viability, reducing sugar content, free-fattyacid, falling number and POD are positive correlation with storage time. Germination-rate,viability, electrical conductivity and falling number are extremely correlation with storagetemperature. Germination-rate, viability, falling number and free-fatty acid are extremelycorrelation with moisture content. Falling number is extremely correlation withgermination-rate and viability. The analysis among storage time and storage temperature havedone, the result is that, storied under25℃condition is similar to the storage condition of room temperature, but the high temperature storage is quite different with the otherconditions.(3) The main boring pests in Japonica brown rice is R. dominica, the reproduction rateof R. dominica in the first month after was observered is the greastst, which was themaximum amount in180d, then the quantity decreased. The grain weight of liaoxing afterworm-eaten was decreased greastly, the percent of dacay volume≥3/4increased with time.Yanfeng have the same trend as liaoxing. The content of protein in liaoxing and yanfeng afterworm-eaten was increased at first then decreased, the original protein content in liaoxing is7.14%then to the max of8.36%when150d, then decreasd to7.92%. The protein content inyanfeng to the max of7.87%when120d, then decreasd to7.66%when270d. The fattycontent of brown rice after worm-eaten was decreased. The original fatty in liaoxing is3.41%,then decreased to0.3%when270d, the original fatty in yanfeng is3.81%, then decreased to0.13%when270d.(4) With the storage time increased, water absorption of rice is increasing, while the pH,iodine blue value and solids of rice soup are decreasing. The hardness of rice increased at firstthen decreased sharply, flexibility and adhesion were decreased with storage time, cohesive ofthe rice was unchanged on the whole, and gumminess of the rice is increasing all the time.Taste rating of rice at15℃and20℃with little change under300d storage periods, the tasterating decreased sharply with high temperature storage.(5) The storage character evaluation model of liaoxing is Y=92.57+0.83X脂肪酸值-2.08X电导率, while the storage character evaluation model of yanfeng is Y=-99.42+4.03X脂肪酸值-1.44X电导率. The changing trends of germination rate, viability and free-fatty acid of brown rice could bewell reflected by first order kinetics, and all of these are suitable to Arrhenius equation.Different varieties of brown rice with different activation energy, and the activation energy ofgermination rate and viability are greater than that of free fatty acid with one sample.