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The Properties And High Value Utilization Research Of Tilapia Skin Collagen

Posted on:2014-09-06Degree:MasterType:Thesis
Country:ChinaCandidate:G H XiaFull Text:PDF
GTID:2181330467485079Subject:Food Science and Engineering
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China is the largest country of tilapia aquaculture and production in the world. A large number of by-products, such as fish skin, fish scale, fish bone, was produced during the rough machining of tilapia. Fish skin, which is the larger proportion of these by-products, has been selling as forages or directly discarding, it is a greatly waste that rich collagen resource of fish skin has not been fully used. In this study, we discussed the efficient and high value way of tilapia processing, in order to promote the utilization of tilapia in food industry, cosmetics and other fields, improve the economic value of tilapia. The main research contents were as follows:1Study on the preparation and properties study of tilapia skin collagenTilapia skin is rich in collagen which is account for about81%of the crude protein. The extraction ratio of skin collagen though hot water was16.02%, the purity of collagen was95.65%. The collagen had a maximum absorption peak at212nm,and none at280nm,275nm,257nm, it was indicated that the tilapia skin collagen was lacked of Trp, Tyr, Phe. The collagen, which minimum gel concentration was10mg/mL, hardness248g, springiness2.18mm, chewiness1.8mJ, exhibit good gel performances and it also has good oil-holding capacity,its isoelectric point was5. The collagen has good emulsifying property which is influence by temperature, pH, and ionic strength. The emulsifying property of collagen was significantly improved by pectin at a mass ratio of4:6, and the mixture exhibit well emulsifying property at pH3-10.2The preparation and antioxidant activities of collagen low molecular weight peptideOptimization of the preparation technology for antioxidant peptides from tilapia skin collagen was carried out. On the basis of the hydrolysis of Alcalase and Trypsin, The method of response surface analysis of Orientase20A with4factors including hydrolysis temperature, time, pH and enzyme to substrate ratio [E/S] on the degree of hydrolysis and DPPH radical scavenging activity was adopted. The optimal hydrolysis conditions are as follows:hydrolysis temperature41.74℃,pH3.97, hydrolysis time6h,[E/S]1.5%. The experiments of antioxidant activity also show that the peptides from tilapia skin collagen could present the strong antioxidant activities to the DPPH and ABTS radical, and the IC50was10.78mg/mL and8.26mg/mL, respectively, the results was similar to the reducing power test. The results of determination of the molecular weight indicate that we could get low molecular weight peptides through three enzyme hydrolysis, the peptides which molecular weight lower then1355Da account for52.8%.3Study on desalination of antioxidant peptides from tilapia skin collagenThe desalting technology of antioxidant peptides from tilapia skin collagen by DA201-C macroporous adsorption resin was investigated. The results indicated that the optimum condition for desalting was obtained as follows:The static absorption rate and absorbing capacity was82.56%and54mg/g, respectively; loading sample concentration of60mg/ml, sampling flow rate of1mL/min and75%alcohol as eluent. Under these conditions, the desalination rate was97.13%and recovery of peptides was81.16%, the antioxidant activity was increased to39.58%at the concentration of0.245mg/mL. In conclusion, it is available and effective to desalt the antioxidant peptides from tilapia skin collagen by using DA201-C macroporous absorption resin.4Isolation and characterization of antioxidative peptides from tilapia skin collagenFour different peptides showing antioxidative activity were isolated from the hydrolysate using DA201-C macroporous adsorption resin which were eluting with different concentration of alcohol, the F3peptide fraction showing strongest antioxidative activity which ABTS radical scavenging rate was21.63%. The SAX anion exchange chromatography was applied to purify the F3peptide fraction, the isolated peptide fraction of F3-2showing the highest ABTS radical scavenging activity, which was27.08%at the concentration of0.1mg/mL. The determination result of amino acid compositions of F3-2peptide fraction shows that it Contains eighteen kinds of amino acid, including seven kinds of essential amino acid, but lacked of Typ. Ala was the most abundant amino acid and then was Gly, Pro, Hyp.5Study of collagen polypeptide chelated with calcium and Antioxidant activityOptimization of the preparation for Tilapia fish skin collagen polypeptide chelated calcium was carried out. Alcalase, Neutrase and Orientase20A were utilized for preparation for collagen polypeptide, the polypeptide was then chelated with calcium. The orthogonal design with4factors including temperature, time, pH and polypeptide to calcium ratio was adopted by measuring chelate ratio. The optimal chelate conditions were as follows:chelate temperature50℃, chelate pH8, chelate time30min, chelate polypeptide to calcium ratio was7:1.under the optimized conditions,the chelate rate of ca-polypeptide could reach78.04%.The formation of ca-polypeptede chelate was confirmed by the UV-VIS and FT-IR spectra. The results indicated that the UV-VIS and FT-IR spectra absorption wavelength of ca-polypeptede chelate were shifting apparently, in other words, it was demonstrated that the calcium was chelated with polypeptide and the chelate has stable structure. The effect of ca-polypeptide to the stabilization of corn oil was shown that the stabilization of corn oil with ca-polypetide was significantly improved comparing the corn oil with calcium.
Keywords/Search Tags:tilapia skin, collagen, peptide, Antioxidant, desalt, purify
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