Determination Of L-Selenium-Methyl Selenocysteine In The Selenium-Riched Extruded Rice

Selenium is an essential trace mineral element in the human body,which has the effect of improving human immunity and inhibiting cell cancer.Selenium cannot be synthesized by itself,and it can only be eaten by food to help the body.Therefore,the development of economical,convenient,and selenium-rich foods suitable for long-term consumption has a very broad prospect.However,the intake of excessive selenium may cause harm to the human body.Therefore,the safety of selenium-enriched foods and reasonable consumption have also attracted much attention.The quasi-deterministic quantification of various types of selenium in selenium-enriched foods will help regulate the market for selenium-enriched foods,curb counterfeit products,and correctly guide people to rationally select and consume selenium-enriched foods.At present,the development and research of selenium detection methods in foods is progressing rapidly,but different detection methods have their advantages and disadvantages in actual detection,and need to be optimized and improved in a targeted manner.In this project,the selenium nutrition-enhanced recombinant rice was used as raw material to establish and optimize the UV-visible spectrum detection method for total selenium in selenium nutrition-enhanced rice and liquid chromatography mass spectrometry of L-selenium-methylselenocysteine(MSC).Use together.This project focuses on the detection technology and optimized detection method of total selenium and organic selenium in exogenous added selenium nutrition for reconstituted rice,which can provide technical reference for qualitative and quantitative analysis of organic selenium in food.The detection technology was used as a means to study whether the effects of high temperature,high pressure and high shear force on the stability of the nutrient enhancer MSC in selenium nutrition-enhanced rice were affected during the extrusion process.The main findings are as follows:(1)Determination of total selenium detection method and test parameters of selenium nutrition fortified recombinant riceThe total selenium content in the selenium-enriched recombinant rice was determined by UV spectroscopy:0.5000 g of selenium-enhanced recombinant rice sample was digested and 0.5 ml of 5%EDTA-2Na solution and 1.5 ml of 1%concentration were added at pH 1.5.The o-phenylenediamine solution was made up to 10 ml and reacted for 40 min;then the reaction mixture was extracted with cyclohexane for 3 min,and the seleno complex 3,4-benzo-1,2,5-in the extract was detected.The absorption of diazonium selenium brain at a wavelength of 330 nm was used to determine the total selenium content of selenium-enriched recombinant rice.The results showed that under the optimized conditions,the linear regression equation in the concentration range of 1μg/ml~5μg/ml was A=0.1285c+0.0053,R~2=0.9982,and the recoveries of the method were 95.56~111.20%.(2)Established high performance liquid chromatography-mass spectrometry(HPLC-MS/MS)for determination of exogenous organic selenium MSCs in selenium-enriched recombinant riceThe content of exogenous organic selenium MSC in selenium-enriched recombinant rice was determined by HPLC-MS/MS:the selenium nutrient-enhanced recombinant rice was pulverized at room temperature,passed through a 120 mesh sieve,and then an acetonitrile aqueous solution(v:v=1:1),the extraction effect was best when extracted by ultrasonic extraction for 70 min.The Themo AQUASIL C18column(150 x 2.1 mm,3μm)was then used as a mobile phase with a gradient of 5%aqueous acetonitrile(0.01%formic acid)and 95%aqueous acetonitrile(0.01%formic acid).Quantitative analysis of MSCs was performed using multiple reaction monitoring(MRM)positive ion mode(m/z 183.99→166.96).The results showed that under the optimal detection conditions,the standard curve showed good linearity in the concentration range of 20 ng/ml~500 ng/ml.The regression equation was A=2449.9c-5003.8,R~2=1,and the detection limit was 1.36 ng/ml.The spiked recovery of the method was 95.62%~99.35%.(3)The effect of extrusion temperature on the stability of MSC in the process parameters of selenium nutrition-enhanced recombinant rice production was studied.In order to simultaneously satisfy the ability to produce the formed selenium nutrient-fortified reconstituted rice,fix the temperature of other temperature zones,change the temperature of the three zones,and study the effect of temperature on the MSC in the selenium nutrition-enhanced reconstituted rice during processing.The results show that the extrusion temperature in the preparation process has little effect on the stability of total selenium and methyl selenocysteine of selenium-enriched recombinant rice.It was verified that the process conditions of the twin-screw extruder originally set by the selenium nutrition-enhanced reconstituted rice can be stably stabilized under the premise of producing high-quality recombinant rice.