| As a kind of safe food, egg contains high protein and affluent lipide and isalso the sourceof some vitamin and mineral matter, what is more, easy to absorb and not expensive.Therefore, egg is known as a nutrition food to maintain life. There are more and morecountries that are attaching importance to the deeper processing of egg these years, especiallysome outstanding breakthrough in the development of the extraction of functional ingredientsin egg yolk. At present, there has been some obvious development of egg product in ourcountry, however, the gap between our country and some other developed countries is stillvery big, such as few researches, low technology level, few kinds of deeper eggproducts.(Chi，2001). To meet the requirement of egg product consumption, to expand thepathway of egg resource and improve the high added value, developing the functional factorscompressively is very prospective in the future.In this study, egg yolk protein was used as the raw material. This experiment hasconducted a systematic researches on the egg yolk polypeptide preparation, the purificationand the biological activity, the main conclusions are as follows:egg yolk protein was used as the raw material to prepare polypeptides by enzymatichydrolysis. In order to obtain polypeptides from egg yolk protein as much as possible, theoptimal hydrolysis mode of egg yolk protein was selected from hydrolysis with pairwisecombination (used sequentially or simultaneously) of Flavourzyme, Alcalase based on thecomparison of Neutrase and Protamex. The effects of enzyme dose, complex enzyme ratio,hydrolysis time ratio, pH on the degree of hydrolysis (DH) and peptide concentration wereresearched and the parameters for optimum were obtained by using Response Surface Method(RSM). Results show that the optimal enzymatic production process was obtained bysequential hydrolysis for2h using Alcalase at55℃and pH7.2with a material/liquid ratio of1:9and0.8%enzyme dose followed by2h using Flavourzyme with0.4%enzyme dose, whichgave13.31%DH and1.85mg/mL peptide concentration.By utilizing ultrafiltration to separate enzynolysis of the egg yolk in the test. The effectsof operating pressure, temperature, pH and concentration of filtrate on ultra-filtration fluxwere investigated by single-factor method. Result showes that the best separate condition waswas obtained by20min ultrafiltration at0.10MPa and25℃with the concentration of filtrateof6%, which gave24.37mL/m2·min ultra-filtration flux. Utilize the zeolites column to purify the egg yolk polypeptide in the test. Test result showes that the egg yolk polypeptide solutionis separated by Sephadex G-15gel filtration chromatography,buffer with NaCl of0.25mol/Lsolution elute, get4peptides components named EYP-1、EYP-2、EYP-3and EYP-4. Theirmolecular weight are5810Da、1330Da、894Da、557Da. Utilizing the high performance liquidchromatogram to carry out further purification to the egg yolk polypeptide,,can get3peptidescomponents named EYP-4-1、EYP-4-2and EYP-4-3.Through the antioxidant test of the egg yolk polypeptide outside the body, theantioxidant stability properties of egg yolk peptides obtained from egg yolk protein bysequential hydrolysis were measured with respect to temperature and pH. The results showedthat the scavenging capacities of egg yolk peptides against hydroxyl free radical, superoxideanion and DPPH free radicals were all increased with increasing egg yolk peptidesconcentration. Meanwhile, temperature and pH had a great impact on the antioxidant activityof egg yolk peptides. The storage of egg yolk peptides at pH12.0for4h could result in theloss of antioxidant activity. |
PDF Full Text Request