The Value-raised Utilization Research Of Gelatin Extracted From Tilapia Scale

The gelatin was extracted from the scale of tilapia by the hot water method in this paper, and the value-raised utilization of this gelatin was researched. The primary results were as follows:1. Study on the preparation and properties of gelatin extracted from tilapia scaleGelatin was extracted from tilapia scale (FSG) by hot water method. The extraction ratio was7.08%(on dry base), the purity was95.35%, and the molecular weight was mainly concentrated from60KDa to130KDa. The pH, plasma and isoelectric point of the FSG were7.01,6.84and4.50. The hardness, adhesion, viscosity and elasticity were352g,42g,2.4mJ and0.51mm respectively. FSG (0.25mg/mL) showed the maximum absorption peak at212nm. The results presented that the properties of FSG were similar to the gelatin derived from mammalian.2. The properties of modified FSGThe modificatiory condition of FSG by TG (transglutaminase,100U/g) was relatively mild. This modified FSG was stable with a hardness of508g and a molecular weight distribution of120KDa to200KDa. And the degree of the modificaiton could be controlled by the amount of enzyme and the enzyme reaction time. EGCG (epigallocatechin gallate ester) modified FSG indicated a small range increasing in molecular weight and a hardness of394g. The adhesion between FSG and EGCG was not strong, so that it had a special property that would release EGCG.3. The application of FSG modified by TG in microencapsulation(1) Cosmetic microcapsule. The cosmetic L-ascorbic acid (AA) sustained-release microcapsules was prepared by ultrasonic combined with emulsion process while FSG as wall material, AA as core material, liquid paraffin as mobile phase. The preparing conditions was optimized by the orthogonal test (L9(34). The resultes indicated that the highest encapsulation rate was81.17%with15mg/mL FSG,7.5mg/mL AA,150μL AEO-9,0.12g/mL TG and40℃of solidificaiton temperature for4h. The encapsulation rate was higher than the general encapsulated rate about50%while gelatin as wall material. The encapsulation rate was43.50%while FSG was substituted by the pursued mammalian gelatin and65.70%while the TG was substituted by glutaraldhyde. The target microcapsule was similar to spheroid with the average particle size of5.37μm. The microcapsule could sustain releasing AA at different temperature with different releasing rate. At5℃and25℃, the encapsulation rate decreased to43.50%and4.70%at the30d, respectively. When the microcapsule was placed at37℃for6h, it was39.2%.(2) Edible microcapsule. On the base of the conditions of preparing cosmetic microcapsule, the edible microcapsule was prepared. The corn oil was used as the mobile phase instead of liquid paraffin; sobitan monostearate (span65, S-65) was used as emulsifier in place of AEO-9. The orthogonal test (L9(34) results showed that when the concentration of FSG was15mg/mL; the AA was7.5mg/mL; the dosage of S-65and corn oil was105μL and22mL; the time of cross-linking was6.5h; the encapsulation rate of this microcapsule was90.60%. And the encapsulation rate was only58.50%while FSG was substituted by the pursued mammalian gelatin and71.50%while the TG was substituted by glutaraldhyde. The edible microcapsule got an average particle size of3.31μm which was similar to the cosmetic microcapsule. Before and after spray drying, the edible microcapsule hold an encapsulation rate of AA and a releasing rate of AA were32.14%and73.82%at37℃for6h, respectively.4. The application of FSG modified by EGCG in fresh keeping of tilapia filletsColor, pH, hardness, volatile basic nitrogen, TBARS value, total bacterial colony counts as indexes were detected in the study of fresh keeping of tilapia fillets.0%,2.5%and5%of FSG (w/v) and0%,0.1%,0.2%EGCG (w/v) were used respectively to keep the fresh of tilapia fillets. The results indicated that both0.2%EGCG and5%FSG could keep the freshness of tilapia fillets and extend the shelf life of tilapia fillets at least8days respectively. However,0.2%EGCG modified5%FSG presented the strongest effect on tilapia preservation than EGCG or FSG working individually.