| With the increase of oyster output year by year in our country,the form of oyster products is still mainly based on primary processed products such as fresh products,dried products,condiments,etc.Therefore,the development of new products has become an inevitable trend of the oyster industry.Iron deficiency anemia(IDA)is a global nutrition deficiency problem to be resolved urgently.Peptide-derived iron supplements have outstanding advantages in enhancing iron digestion stability,bioavailability and improving IDA.Oyster,rich in highquality protein,is an excellent source for the development of various bioactive peptides.However,there are few related studies on oyster peptides chelated iron.Therefore,in this paper,oyster protein,as a raw material,was used to prepare oyster peptides with ferrous binding activity,which was organically combined with iron salt to prepare chelate,and structure and properties of the chelate were studied,which will provide a constructive reference for the highvalue development and utilization of oyster resource.The specific research results are as follows:Firstly,the preparation of oyster peptides with ferrous binding activity was by enzyme method.The result of enzyme type selection test showed that animal proteolytic enzyme was the best enzyme for preparing oyster peptides with ferrous binding activity;the single factor experiment indicated that the optimal enzymatic hydrolysis process was as follows: solid liquid ratio of 1:15,enzyme amount of 1000 U/ g,enzymolysis time of 2 h,and p H = 10.Under this condition,the ferrous binding capacity of oyster peptides was up to 95.97 ± 0.30%,the degree of oyster protein hydrolysis was 37.48 ± 1.32%,and the protein recovery rate was 81.55 ± 0.86%.Besides,according to the Lineweaver-Burk method,the kinetic model of the hydrolysis of oyster protein by animal proteolytic enzyme was deduced as: V=0.2562[S]/(20.357+[S]).The molecular weight of oyster peptides was determined by high performance liquid chromatography,it was found that the molecular weight of oyster peptides was mainly distributed between 200 Da and 1000 Da,of which 222～504 Da accounted for 63.12%.Secondly,the preparation process of oyster peptide ferrous chelate was explored.Through single factor experiment,it was found that the optimal concentration of oyster peptides was 1% and the best chelating temperature was 35 ℃.Based on the single factor experiment,with chelation rate as response value,the chelation process response surface optimization test was performed.The results showed that the optimal process parameters of the chelation reaction were as follows: the mass ratio of oyster peptides to ferrous chloride of 4.4,p H = 6,and the ascorbic acid concentration of 1.4%.Under this condition,the chelation rate was up to 82.18 ± 0.64%.Finally,the structure and properties of oyster peptide ferrous chelate were analyzed.The results of ultraviolet spectrum,infrared spectrum,XRD and scanning electron microscopy analysis denoted that the oyster peptide ferrous chelate absolutely was a new substance different from the peptide,and it was speculated that ferrous ion was bound to peptides predominantly by interacting with the nitrogen atoms of amino groups and the oxygen atoms of carboxylic acid groups.The vitro antioxidant experiments demonstrated that oyster peptide ferrous chelate had good free radical scavenging ability,and its scavenging abilities to DPPH free radicals,hydroxyl free radicals,and ABTS free radicals were significantly stronger than oyster peptides.The stability experiment results revealed that: the oyster peptide ferrous chelate was stable at p H value 5～9;It also presented good digestive tolerance in simulated gastrointestinal digestion test,and the iron retention rate finally maintained at a level of 74%.Analysis of amino acid indicated that aspartic acid,glutamic acid,arginine,lysine and cysteine might provide ferrous ion binding sites for oyster peptides. |
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