Studies On Physicochemical Parameters And Texture Changes Of Lateolabrax Japonicus Meat During Storage And Transportation

Lateolabrax japonicus, which have nice flavor, tender texture, many medical and nutritional functions, is one of the economic fish in coastal and potamic area. In this paper, the Lateolabrax japonicus was chosen as the material and the following researches were carried out.Firstly, application of nonlinear curve fitting method in analyzing stress-relaxation empirical data of food was studied. Compared with the successive approximate method, nonlinear curve fitting method was studied by analyzing the stress-relaxation curves of four kinds of materials (ham, cheese, Lateolabrax japonicus and whelk). The results suggested that the nonlinear curve fitting method could fit generalized Maxwell model. The analytic results were steady, credible, and with a high fitting degree. In addition, it had features of easy-operation and swiftness, which could be applied in many kinds of materials. Nonlinear curve fitting method was proved to have advantages over the successive approximate method for food with a high moisture content and complicated viscoelasticity.Secondly, the quality and texture changes of Lateolabrax japonicus meat during frozen storage were studied. Tissue structures, texture profile analysis and changes of rheological properties (elastic modulus E0, stress-relaxation time t1, viscosityη1, rupture strength), as well as the total number of bacteria, K value, TVB-N, pH value and sensory scores were determined. The results suggested that the total number of bacteria decreased, while K value and TVB-N increased with the extension of storage time. As the storage time extend, the space of the myofibril increased, the tissue structure deteriorated, elastic modulus Eo increased, and rupture strength, hardness, springiness, cohesiveness and chewiness decreased, while viscosityη1 and stress-relaxation time t1 had no significant changes. Compared with that of refrigerated samples, frozen storage samples have characteristics of high quality freshness and long shelf-life. It showed that freezing could effectively inhibit the activity of enzymes in the meat of Lateolabrax japonicus and the growth of micro-organisms, so that it could alleviate the decomposition of protein. As a result, freezing storage is an effective method to extend the storage time of Lateolabrax japonicus.The third, the quality and texture changes of Lateolabrax japonicus meat during partially frozen storage were studied. Tissue structures, texture profile analysis and changes of rheological properties, as well as the total number of bacteria, K value, TVB-N, pH value and sensory scores were determined. The results suggested that the total number of bacteria, K value and TVB-N increased with the extension of storage time, while pH value decreased first and then increased. As the storage time extend, the space of the myofibril increased, the tissue structure deteriorated, elastic modulus E0 increased, and rupture strength, hardness, springiness, cohesiveness and chewiness decreased, while viscosityη1 and stress-relaxation time tj had no significant changes. Compared with that of refrigerated samples, the shelf-life of partially frozen storage samples could be extended for 20 days longer. It showed that partial freezing could effectively inhibit the activity of enzymes in the meat of Lateolabrax japonicus and the growth of micro-organisms, so that it could alleviate the decomposition of protein. As a result, partial freezing storage is an effective method to extend the storage time of Lateolabrax japonicus.Finally, keeping alive of Lateolabrax japonicus was studied. The live time of Lateolabrax japonicus was confirmed in different concentrations of anesthetic MS-222. The primary components, lactic acid, texture profile analysis and changes of rheological properties in different alive situation were investigated. The results were shown that lactic acid increased with the extension of keeping alive of anesthetic MS-222, while primary components, tissue structures, texture profile analysis and rheological properties had no significant changes. It showed that anesthetic MS-222 could effectively inhibit the respiration intensity and metabolic rate of Lateolabrax japonicus, so that it could effectively extend the carrying time.