Tilapia Fish Protein Peptides And The Preparation Of Zinc Complexes With Biological Activity

Preparation technology of tilapia protein hydrolysates by built single factor test, orthogonalexperiment and response surface methodology （RSM） were defined with the index degree ofHydrolysis （DH）, TCA-soluble nitrogen index （TCA-NSI） and yield of acid-solubility peptide（YASP）. The effect of hydrolysis temperature, pH, the quantity of Alcalase, the ratio ofLiquid-to-solid on DH, TCA-NSI, YASP were studied by RSM, rgression model was obtained byresponse surface analysis. Regression model indicated that the optimal condition hydrolyzedAnimal Protein of Tilapia Meat by Proteinase was described in the following：hydrolysistemperature54.30℃, pH8.77, the quantity of Alcalase2.4L was3702U/g, the ratio ofLiquid-to-solid was3.06, hydrolysis time1hour, and established a mathematic model ofhydrolysis technology. Form such mathematic model, the DH （%）, TCA-NSI （%） and YASP （%）calculated to33.63%,22.10%,64.55%respectively. Experiment result showed that the DH （%）,TCA-NSI（%） and YASP（%） were33.57%,22.09%,64.52%, the predictive value were andexperimental value have small deviation, indicated that Regression model was reasonable andreliable.Mathematic model of DH（%）, TCA-NSI（%） and YASP（%） were following：DH=33.49-0.65B-0.71CD-1.08A²-0.62B²-0.93C²-0.65D²TCA-NSI=22.14-0.60AC-0.55AD-1.05BC-2.19A²-0.75C²-0.72D²YASP=64.32-0.62A-0.56B-0.69C-0.78AC-0.55BD+1.09CD-0.85A²-0.78C²-2.32D²A: reaction temperature （℃）, B: pH, C: enzyme quantity （U/g）, D: liquid-to-solid ratio （W/W）The result of study on distribution of hydrolysis indicated that four peptides’ molecularweight were5721,1397,618,273. and the hydrolysis of1397has more clear content than others.Four single component of hydrolysate were isolated and purified by sephadex G-25, G-15chromatography.The optimum chelating conditions of peptide with zinc acetate were pH5.0, temperature45℃, and mass ratio of N-Zn4:1, reaction time40min. Under such conditions, yield ofZn-peptide complexes was up to63.02%, chelating rate of Zn was77.86%.The prodect was testified by IR and UV. The result showed that Zn²⁺-peptide complexeswere chelated after peptide and zinc acetate reaction, there have strong binding between Zn and peptide amino and carboxyl groups. Comparison of infrared spectrum of Zn²⁺-peptide complexesand mixture of peptide and znic acetate, result showed that Zn²⁺-peptide complexes weregenerated after reaction.The30-day feeding experiment showed that specific growth rate, the growth rate of fourorgan, content of lysozyme and activity of superoxide dismutase （SOD） and alkaline phosphatase（AKP） were remarkably increased by feeded feedstuff containing peptide, Zn²⁺-peptidecomplexes, znic acetate. Feed conversion ratio was significantly reduced as the additiveincreased. The content of total protein, albumin, and globulin were elevated too. The groupssupplied Zn²⁺-peptide complexes, peptide, znic acetate can improve phagocytosis capability ofmouse macrophage, the phagocytosis percentage and phagocytosis index of adding Zn²⁺-peptidecomplexes were the highest.