Selenium-chelating pea oligopeptide, and preparation method and use thereof

A selenium-pea oligopeptide chelate, wherein the selenium-pea oligopeptide chelate contains an amino acid sequence of SEQ ID NO:2, and a mass content of SEQ ID NO:2 is not less than 25 ng/mg;

• acid soluble protein content of the selenium-pea oligopeptide chelate is more than 23%, total nitrogen content is more than 23%;
• the selenium-pea oligopeptide chelate is composition of selenium-pea oligopeptide chelate with different molecular weight, and a portion of selenium-pea oligopeptide chelate with molecular weight less than 1000 u accounts for more than 85% of a total amount of the selenium-pea oligopeptide chelate;
• and selenium content is not less than 0.08 g per 100 g of the selenium-pea oligopeptide chelate;
• wherein the selenium-pea oligopeptide chelate is a reaction product of an aqueous solution of pea oligopeptide and sodium selenite, and selenium of the sodium selenite is stably combined with the pea oligopeptide in a way of covalent bond so that after the selenium-pea oligopeptide chelate is prepared and then subjected to digestion treatment in at least one of following three ways, a change rate of the selenium content is not more than 3% with respect to the selenium content before the digestion treatment:
• hydrolyzing for 4 hours by a pepsin at a pH value of 2 and a temperature of 37° C.;
• hydrolyzing for 6 hours by a trypsin at a pH value of 7.5 and a temperature of 37° C.;
• maintaining a temperature constant at 37° C., and firstly hydrolyzing for 4 hours by a pepsin at a pH value of 2, and then continuing to hydrolyze for 6 hours by a trypsin at a pH value of 6.8;
• wherein the change rate of the selenium content is a mass percentage of a mass of selenium decomposed during the digestion treatment of the selenium-pea oligopeptide chelate to a total mass of selenium in the selenium-pea oligopeptide chelate before the digestion treatment.