| Objective.Selenium(Se)is an essential trace metalloid and the only functional element that is genetically encoded into proteins.Insufficient and excessive intake of selenium can be harmful to human health,and humans are generally supplemented with diet and drinking water.The study of selenium distribution and chemical forms in selenium-enriched foods is beneficial to the screening of biologically active selenium species and to the in-depth development and utilization of selenium-enriched functional foods.Methods.1.Plant food corn seeds from different locations in Enshi Prefecture were selected to study the distribution and chemical forms of selenium.2.Aiming at the animal food yellow trout in Enshi Prefecture,the distribution and chemical forms of selenium were studied.3.The speciation of trace inorganic selenium in common water sources in Enshi Prefecture was analyzed by solid phase extraction and enrichment.Results.1.Firstly,the experiments showed that the selenium content of maize seeds from Enshi Shuang He and Jian Shi Qi Yang Ba were 1.0580±0.0322 mg/kg and 0.4537±0.0360 mg/kg,respectively,which were selenium-riched maize,and their distribution patterns showed that the seed coat contained 0.1113～0.4977 mg/kg,the endosperm 0.2431～1.0869 mg/kg,the embryo 0.6293～1.2692 mg/kg,and the distribution pattern of selenium in maize seeds showed that embryo>endosperm>seed coat.Secondly the Enshi H,Jian Shi Chang Liang Zi,Jian Shi Qi Yang Ba three properties of maize seeds corresponding to the processing of popcorn,the measured total selenium content of 0.0525±0.0002mg/kg,0.0641±0.0036 mg/kg,0.5085±0.0490 mg/kg,popcorn is divided into two parts of the receptacle and petals,the receptacle from the maize seed embryo and a small amount of endosperm expansion The corresponding selenium content of0.0613±0.0033 mg/kg,0.0878±0.0053 mg/kg,0.6293±0.0223 mg/kg;the petal part of the corn seed endosperm and seed coat puffed,the corresponding selenium content of0.0443±0.0012 mg/kg,0.0546±0.0015 mg/kg,0.2431±0.0015 mg/kg,0.2431±0.0120mg/kg,calculated by the ratio of receptacle to petal mass,to obtain popcorn selenium content increased by 12.65%,11.40%,12.07% compared to the original corn seeds,considering the loss of water during the expansion of corn seeds,so within the error tolerance and reliable results.The distribution pattern of selenium content in corn popcorn confirms the distribution pattern in the physiological partitioning,and the expansion process did not cause the migration loss of selenium.Finally the extraction conditions of selenium chemical morphological analysis were further optimized for corn embryos from Qi Yang Ba,and the experiments showed that the extraction of selenium in corn embryos reached 22% with the addition of 4% pepsin,water-to-material ratio of 7.5 m L/g,and 24 hours of extraction;the highest extraction rate was achieved when the protein of corn embryos was extracted with a weak alkaline solution,p H=9.0,water-to-material ratio of 10 m L/g,and 40°C for 1 hour.The extracted protein solution was separated and purified by SDS-PAGE electrophoresis analysis showed that four proteins were separated with molecular weights of about 85 k Da,40 k Da,30 k Da and 15 k Da,and the determined selenium contents were 1.9371±0.1069 mg/kg,1.4165±0.0891 mg/kg,1.2627±0.1750 mg/kg,and 0.5774±0.1695 mg/kg.2.The selenium content of Enshi yellow trout was0.1150±0.0032 mg/kg,0.1800±0.0105 mg/kg,0.0973±0.0406 mg/kg,respectively,according to the physiological structure partitioned into three parts: fish head,fish body and internal organs,and the edible part reached the selenium-riched aquatic standard,with selenium content of fish body > fish head.The optimal conditions for the extraction of fish body proteins in acidic solution were optimized: p H of the extraction solution was 2.0,water to material ratio 10 m L/g,and extraction at 4°C for1 hours.SDS-PAGE analysis of fish body proteins showed that three proteins with molecular weights of 130 k Da,40 k Da,and 30 k Da were separated,and the first two proteins contained 0.3447±0.0064 mg/kg of selenium and 0.2491±0.0161 mg/kg,and the 30 k Da protein did not contain selenium.3.For the morphological analysis of inorganic selenium in the commonly used drinking water in Enshi,the adsorption capacity of MOF solid phase extractant was dynamically investigated to optimize the selection of solid phase extraction separation and enrichment conditions.The results showed that the recovery of selenium was more than 80%.The detection limit of the method was 7 pg/m L,the relative standard deviation(RSD,n=7,c=0.3 μg/L)was1.86%,the spiked recoveries ranged from 94% to 103%,and the theoretical enrichment multiple was 33 times.The method measured 0.1974±0.0102 μg/L of selenium in Enshi mineral water and 0.0885±0.0048 μg/L in tap water.Conclusion.In this paper,the morphological analysis of selenium in selenium-riched foods in Enshi was studied from three perspectives: plant,animal and water.For plant foods people should make full use of the selenium bioactive substances in the seed embryo part;animal selenoproteins are higher than plant selenoproteins,prompting people to screen more selenoprotein species from animal foods;solid phase extraction graphite furnace atomic absorption spectrometry analysis method to analyze the inorganic selenium morphology in drinking water is simple,rapid and easy to promote the application. |
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