The Tilapia Fillets Discoloration Mechanism And Protecting Color Technology

Tilapia is a kind of good eating fish and economic fish with high nutrition, good taste, a wide breeding range, low cost and good economy efficiency. In this paper, the physical, chemical and storage properties of tilapia’s flesh were studied. On the basis of the existing processing technology, the changes of compressing texture parameters, chemical compositions and appearances of tilapia fillets’are studied, focusing on the prevention of the fading of the CO colored tilapia fillet and the browning of the original tilapia fillet during their storages. The partitioning method, processing eligibility, color change rule, pigment content change rule and the color protection means of tilapia were discussed. And a new improved method of existing frozen tilapia fillets’storage technology was presented. The experimental conclusions in this paper were as follow:(1) By the different change trend of the tilapia’s chromatism parameters, Mb content and the met-Mb’s percentage content, its frozen storage process can be devided into the prior period of storage (1d～22d) and the last of storage (>22d). In the prior period of storage, the color of tilapia fillet changes in a lesser degree but speed increases gradually. After arriving late storage, the values of chromatism linear decreases, and the rate of Mb content’s and the met-Mb’s percentage content’s changing reachs the maximum and then decrease gradually.(2) CO coloring, water glaze, and Potassium sorbate soaking can slow the rate of browning tilapia to some extent. Their degrees of improvement in the order of water glaze> CO coloring>soaking.(3) Their is a highly positive correlation between the coefficient of the change of the met-Mb’s percentage content and the coefficient of the change of a*. An experiment with the water glaze of original tilapia fillet mixed into0.3192%o erythorbic acid and0.6808%o sorbic acid get a result with the coefficient of the change of the met-Mb’s percentage content being13.79, which means it effectively reduces the browning rate of the original tilapia fillet. An experiment with the water glaze of CO colored tilapia fillet mixed into0.3196%o erythorbic acid and0.6804%o sorbic acid get a result with the coefficient of the change of the met-Mb’s percentage content being10.42, which means it effectively reduces the fade rate of the CO colored tilapia fillet.(4) The abdomen of tilapia are very different from the other parts with the physical and chemical properties of texture parameters, fat content, water activity, which makes it more easily to be oxidized deterioration and discoloration. Therefore its taste declines after storage was also faster. It is suggested that we can cut the abdomen in the processing of tilapia fillets and for other use. In processing of the other tilapia products we can also take the various parts to fine processing following the differences of their physical and chemical properties. The main external factors which causes the differences on tilapia fillets’texture parameters are the interaction with the air and the lost of the water, while the internal factors are the changes of its tissue structure, physical and chemical properties.