Effects Of Selenium Biofortification On Nutrient Components And The Utilization Of Se-Containing Protein Modified By Phosphorylation

Nearly half of the world's population is suffering from malnutrition caused by the lack of iron,zinc,calcium,iodine and selenium.These mineral elements are found in some of the world's most important crops,such as rice,wheat,cassava,and beans.,potatoes,millet and corn.Therefore,increasing the content of trace elements that can be bio-utilized in edible crops will become an important development direction in modern agriculture,using the least amount of resources to meet the nutritional needs of more people and achieving the goal of bio-enhancement of cereal crops.In this paper,sodium selenite is applied through the foliar surface to achieve the purpose of bio-enhancement of selenium in rice.This study investigated the enrichment and migration of selenium in rice and its effects on grain nutrients,including protein,oil,starch,minerals and polyphenols.The morphology of selenium in grain was determined by LC-ICP-MS and its effect on protein structure.The bioavailability of selenium in selenized brown rice was evaluated by in vitro simulated digestion model.Improve the nutritional value of selenium-enriched rice bran protein and expand its application in the food industry.1.Applying selenite with selenium concentrations of 0,25,50,75 and 100 g Se/ha at the heading stage of rice,the results showed that selenium was stored in the foliage after selenium treatment,and then transported through the stem.The selenium content in the grain was increased,and the selenium content in the brown rice was increased by 11.7 to 39.4 times compared with the control group.And as the concentration of sodium selenite treatment increases,the enrichment of selenium in the endosperm is higher.The increase in Se content in the grain will affect the enrichment of other minerals such as Fe,As,Ni and Cd.The grinding process will cause the loss of selenium,especially in the low concentration sodium selenite treatment group,the loss of selenium is greater than the mass of the dry loss of milling,which is because selenium is mainly present in the bran layer and germ.With the enrichment of selenium,the enrichment ratio of selenium in the endosperm has also been correspondingly improved.Foliar application of sodium selenite can effectively increase the Se content in the grain and is used to meet the needs of Se in people's daily diet.2.Foliar application of sodium selenite does not affect the main nutrient composition of brown rice,including protein,starch and fat.However,the treatment of sodium selenite causes a decrease in the content of methionine groups(Cys and Met),which may be due to the substitution of Se for the S element.At the same time,through the treatment of Se,the fatty acid composition of the grain changed,and the contents of oleic acid,linoleic acid and palmitic acid increased significantly.It was found that selenium treatment affected the amylose content of the grain,which affected the corresponding change of gelatinization characteristics.The enrichment of selenium increased the content of polyphenols in the grain,especially the content of trans-ferulic acid in the bound phenolic acid,which increased from 21.4±0.413 to 25.5±0.142 mg/kg.3.The bioavailability of Se in food can be effectively evaluated by in vitro simulated gastrointestinal digestion model.The treatment of sodium selenite can increase the enrichment content of selenium in brown rice,and the bioavailability of brown rice increases from 57% to 66% with the increase of selenium concentration.Se in the brown rice is mainly in the form of SeMet,which accounts for 22%-40% of total Se,but the recovery of SeMet is reduced under high Se concentration,possibly due to Se and other biological macromolecules other than protein.The reason for the combination.4.Foliar application of selenium fertilizer significantly increased the content of selenium in rice.However,even under the application of high Se concentration treatment,not all Se is converted into an organic selenium compound to participate in the synthesis of general proteins.The gluten component is the main storage site for selenium in rice,accounting for 78% of the total.Based on Se morphological analysis,SeMet synthesis into plant proteins is the main form of Se enrichment in rice after Se treatment.However,an excess of Se will exist as inorganic Se or a free selenoamino acid such as SeMet.Se may affect the metabolism of S to increase the Cys content in gluten,thereby contributing to the thermal stability of the gluten component.5.The use of sodium trimetaphosphate for wet-process phosphoric acid modification can significantly improve the solubility and emulsification activity of selenium-enriched rice bran protein,which is increased by 8.7 times and 8.1 times,respectively.At the same time,the protein digestibility and the bioavailability of Se are increased.By phosphorylation,a large amount of phosphate accumulates and is attached to the surface of the protein molecule,increasing its absolute charge.At the same time,protein structure unfolding exhibits greater flexibility and converts insoluble aggregates in the feedstock to soluble components in the phosphorylated protein by heat treatment under alkaline conditions.In addition,the buried hydrophobic groups are exposed to the outer surface of the molecule and/or react with the phosphate groups,resulting in increased surface hydrophobicity,increased endogenous fluorescence,and a blue shift phenomenon.FT-IR spectroscopy and XPS analysis indicated the presence of phosphate(P=O),confirming that the protein reacted with the phosphate group and affected the secondary and tertiary structure.Phosphorylated RP prepared at pH 9.0 showed good emulsifying activity and stability.