Se Content Changes During The Processing Of Selenium-enriched Brown Rice

Selenium is one of the essential trace elements in human body.This paper mainly discusses the methods of selenium content determination,selenium speciation analysis and the change of selenium content in the selenium rich brown rice processing process.Based on the related experiments,the establishment of an atomic fluorescence spectrometry suitable for selenium content determination in selenium enriched brown rice and the liquid phase atomic fluorescence spectrometry for selenium speciation analysis are introduced,and the change of selenium content in the process of rice milling is analyzed.The results of single factor experiment on wet milling of brown rice were analyzed,and the wet milling process of selenium rich brown rice was determined by orthogonal test.The main results are as follows:(1)to optimize the testing conditions for the determination of selenium content:the best performance is achieved when 10%hydrochloric acid is used as the carrier current and 15g/L sodium borohydride solution as reducing agent;the pretreatment conditions are:the best results are obtained when the digestion solution is running to about 1ml,and the 20s can be restored by heating the 20s at the 180?degree electric heating plate at the pre reduction stage.After optimization,the relative standard deviation(RSD)is 0.1633%.The average recoveries of the samples were up to95.34%.The determination conditions for selenium speciation analysis were optimized.The hydrochloric acid containing 15%of the carrier solution was determined.The reductant was 15g/L borohydride solution,and the digestive solution was 0.15%KI solution.According to these conditions,five kinds of selenium series standard solution were determined.The standard curve of selenium form was linear(R ~2>0.997),and the accuracy and precision met the methodological requirements.(2)to make rice discriminant experiment(dyeing method)for rice samples with different milling rate,and determine the milling rate of 12.3%,15.28%,16.4%and17.1%meters were four,three,two and 15.28%,respectively,and compared with the quality of commercial rice(Enshi's"October").The content of rice like selenium with a reduction of 16.4%was kept well and the eating quality accords with the requirements.By analyzing the change of selenium content in the selenium rich brown rice,it is proved that selenium is not evenly distributed in brown rice.The order of selenium content is:rice bran>brown rice>milled rice;for the complex cortex of brown rice,the distribution of selenium content in the cortex of brown rice is not decreasing from the outside,but the selenium content in the outer layer of brown rice is the highest.The correlation between selenium content and protein content is very significant.(3)the effects of soaking time,soaking temperature,material liquid ratio and wet milling time on selenium content in selenium rich brown rice were tested.The results showed that the soaking time was greater than the soaking temperature on the selenium content.The selenium loss rate of the highest soaking temperature was less than 10%.The loss rate of selenium in the soaking time was as high as 30%;the ratio of material to liquid also affected the selenium content,and the ratio of material to liquid was 1:4.The loss rate of selenium is the lowest.Wet milling time has an indirect effect on the selenium content by affecting the size of brown rice flour.When wet milling 12min,the selenium content tends to be stable.The optimum conditions for wet grinding are:soaking time 5h,material to liquid ratio 1:4,wet milling time12min.In this study,a method for the determination of selenium rich brown rice and selenium speciation analysis was established,and the change of selenium content in selenium rich brown rice in milling and wet milling was analyzed.The degree of judgement of moderate milling and the wet milling technology of selenium rich brown rice were determined,which laid the foundation for the development of selenium enriched products with high selenium retention rate.