Study On The Changes Of ?-carotene Content And Qualities In Paddy Rice During Processing And Storage

Paddy rice is one of the three major grain crops.During the storage,because of the effects of storage humidity,temperature,moisture and other factors,the chroma value of the paddy rice will change with time,and the content of ?-carotene contain will also change.Furthermore,in the processing of paddy rice,the ?-carotene,the color of surface and texture are significantly changed with the deepening of the processing degree.At present,there are few studies on these two aspects around the world.Therefore,studying the changes of ?-carotene and main characteristics in paddy rice during storage and processing have a great effect on the scientific and rational storage and processing of paddy rice.The paddy rice that harvested in 2017 was used as raw material to conduct the project.Then the lab was used to simulate the micro-environment of grain depots for storage.Besides that,the ?-carotene content,the color of surface and texture in paddy rice under different processing conditions(0s,30 s,60s,90 s,120s)were studied,to provides theoretical basis for safe storage and processing of paddy rice.The research results were indicated as below:(1)Extraction and analysis of ?-carotene in paddy riceThe ultrasonic extraction did not require heating,which avoided the loss of ?-carotene due to the thermal degradation.The optimum extraction conditions were as follows: ratio of material to liquid 1:5;extraction for 25 min;ultrasonic power 225 W;extraction times 3 times.The analysis of ?-carotene by HPLC had the advantages of high sensitivity,short time and low dosage.It could effectively separate ?-carotene.The chromatographic conditions were as follows: the column: AcclaimTM C18(250 × * 4.6 mm,5 ?m);the mobile phase: methanol: dichloromethane = 70:30;the detection wavelength was 450 nm;the injection volume 20 ?L;the flow rate 0.8 mL/min;temperature 30 ?;the time 30 min;isocratic elution.The method was applied to extract and detect ?-carotene in rice.The recovery rate was between 95.12% and 100.02% with good accuracy,repeatability and stability.(2)Study on the effect of different processing accuracy on the changes of ?-carotene content and main quality in paddy riceDuring the processing,?-carotene in different water content samples gradually decreased with the increase of processing accuracy.The lower the water content,the greater the loss of ?-carotene.During the paddy rice milling process,the L value of the sample was continuously increased,and the b value and a value were gradually decreased,that is,the whiteness of the sample was increased,the yellowness value was decreased,the redness value was decreased,which resulted in the improvement of the sample quality.With the extension of paddy rice milling time,the hardness,cohesiveness,chewiness and adhesiveness of the samples showed a trend of decreasing gradually,and the springiness appeared to increase.Milling time had a significant effect on paddy rice ?-carotene and its main quality.?-carotene was significantly negatively correlated with L value and springiness,and was significantly correlated with a value,b value,hardness,cohesiveness and adhesiveness.Therefore,the change of ?-carotene content under different processing accuracy could be used as a predictor to reflect changes in surface color and texture characteristics during paddy rice processing.(3)Study on the effects of dynamic storage on ?-carotene content and main characteristics change in paddy riceIn the 150 d storage experiment,the content of ?-carotene in the paddy rice decreased continuously with the prolongation of storage time.During storage,the initial water content and the temperature were different,the variation range of ?-carotene was different.The lower the initial moisture content,the higher the temperature and humidity,the greater the decrease of ?-carotene.Therefore,the low temperature storage and the proper water content were conducive to the retention of ?-carotene.With the prolongation of storage time,the L value decreased continuously.The lower the moisture content,the lower the temperature,the smaller the change value.The a value and b value increased significantly with time.They led to changes in paddy rice quality.There was a significant positive correlation between the L value and the content of ?-carotene.The a value and b value had a significant negative correlation with the content of ?-carotene.Therefore,?-carotene can be used as a predictor of the surface color change of paddy rice during storage.