Preparation, Structure Identification And Bioavailability Of Mung Bean Polypeptide Zinc Chelate

Zinc is one of the essential elements of the human body.Inadequate intake of zinc ions in the daily diet can cause a variety of diseases.In recent years,food-borne protein peptide trace element chelate has become a research focus due to its natural and non-toxic side effects.The structure of the chelate is stable,and it is not easy to precipitate after entering the gastrointestinal tract of the human body,and can be better absorbed by the human body.However,the binding mode of chelate and the mechanism of transport and absorption need further research.Mung bean peptide with zinc binding ability was prepared from mung bean protein as the raw material,and its chelating ability,purification analysis,structural properties and bioavailability were studied.The specific experimental content and results were as follows:(1)Mung bean polypeptide zinc chelation process optimization.The five proteases were screened using the degree of hydrolysis and chelating ability as indicators.The results showed that alkaline protease was the best protease for the preparation of mung bean zinc chelating peptides.Using chelating ability as an indicator,a single factor and response surface method was used to optimize the chelating process.The best process conditions were: peptide zinc quality The ratio was 6.20:1,the reaction temperature was 50?,the reaction time was 83 min,and the p H was 6.3.Under this condition,the chelation rate reached 52.11±0.51 mg/g.(2)Isolation and purification of mung bean protein peptide.In the experiment,the mung bean protein peptide was first separated by ultrafiltration,and it was divided into >10KDa(P1),10 KDa~5000 Da(P2),3000 Da~5000 Da(P3),and <3000 Da(P4).It was chelated with zinc ions under the best chelating process conditions.The results showed that the peptide chelating ability of P4 was 58.16±0.37 mg / g.P4 was purified by size exclusion and high performance liquid chromatography C18.The best chelating ability was 80.82±0.49 mg / g.The purified peptide was analyzed by LC-MS / MS,and the molecular weight of the peptide with the highest match was 1192.56 Da.Its amino acid sequence was Ser-Ser-Glu-Asp-Gln-Pro-Phe-Asn-Leu-Arg.(3)Analysis of Mung Bean Protein Peptide and Its Chelate Structure.Scanning electron microscopy,peptides and chelates have greatly changed the surface microstructure and crystallinity.Ultraviolet and Fourier infrared spectroscopy analysis showed that the amino,carboxyl and amide groups of the peptide participated in the reaction.(4)In vitro bioavailability experiment of zinc ion of mung bean polypeptide zinc chelate.It was found that the solubility of zinc ions of mung bean polypeptide zinc chelate at p H 8.0 was72.30±0.54%,which was significantly higher than that of inorganic zinc salts.In addition,the bioavailability of mung bean peptide zinc chelate was studied using in vitro intestinal digestion simulation-dialysis method.The results showed that the dissolution rate of the mung bean peptide zinc chelate in the simulated gastrointestinal tract and the dialysis rate in the intestine were 98.85±0.39% and 44.24±0.73%,respectively,which were higher than the inorganic zinc salt,indicating that the chelate compound was better absorbed and utilized in the intestine.(5)Experimental study on mung bean peptide zinc chelate cells.Caco-2 cell model was used to detect cell survival rate by CCK8 method,and a cell model was constructed.The effects of mung bean protein peptides on zinc ion transport and absorption were explored from the perspective of cytology.Studies have shown that the optimal concentration of mung bean protein peptide for promoting zinc ion transport is 0.4 mg / m L.The zinc ion utilization rate of the chelate was measured,and the bioavailability of zinc ion of the mung bean peptide was60.54±0.45%.