Study On Material Characteristics Of Conventional Freshwater Fish

Freshwater fish resource in China is rich, and the conventional freshwater fish (black carp, grass carp, silver carp, bighead carp, common carp, crucian carp, bream) yield accounts for about 60 percent of that. Along with the increase of breed dimensions and yield, freshwater fish processing is urgently needed to meet the rising consumption demand. Because of the weakness of basic research of freshwater fish processing and lack of basic data of material characteristics and processing properties of conventional freshwater fish, freshwater fish processing industry is week in our country. In this paper, material characteristics of seven conventional freshwater fishes and heat processing properties of sliver carp were studied, in order to provide the basic data of conventional freshwater fish and theoretical guidance for conventional freshwater fish processing and product development.Take the current market sold conventional freshwater fishes as experiment materials, each part weight percentage, meat-obtain ratio, nutritional composition, pH value, protein composition and texture profile analysis (TPA) of muscle were investigated. Results indicated that: body parameters of conventional freshwater fish were different. The meat-obtain ratio showed differences, black carp was highest 54.33%, bighead carp was lowest 32.80%. The moisture contents of seven conventional freshwater fishes were higher than that of main economic marine fishes 5% to 8%, the fat content of bream was highest 4.08%. PH value were located in 6.5 to 7.0 except that of grass carp, in the range of best pH forming surimi gel. Water-soluble protein of common carp was highest 4.68%, suggesting that rinsing should be intensified during processing common carp surimi products. Salt-soluble protein of grass carp was highest 9.91%, suggesting that grass carp muscle was more suitable for processing surimi products. Comparing TPA testing parameters, textural characteristics of black carp, grass carp and common crap were better than other four freshwater fishes; considering their higher meat-obtain ratios, processing properties of black carp, grass carp and common crap were better than other four freshwater fishes.The sliver carp back muscle was taken as research object, protein denaturation temperature was tested by differential scanning calorimeter(DSC), heat transfer curves of hot water and steam heating were determined, effect of heating on whiteness, mass loss rate, protein content in juice, TPA, pH value of silver carp back muscle were discussed. Results showed that: myosin denaturation temperature were 46.49℃and 59.24℃, actin denaturation temperature was 75.32℃. The heat transfer curve of sliver carp muscle was first smooth, then rapidly rised, and slowly rised finally. The whiteness, mass loss rate, mass of protein in juice and pH value of silver carp back muscle were gradually increased during heated. Different heating conditions of positive and back of silver carp back muscle during steam heating brought about different variation trends. The whiteness was increased quickly when the temperature reached to 60℃, which induced the changes of texture. Denaturation degree and stability feature of protein components during heating were analysised by SDS-PAGE electropheresis. The results showed that the proportion of water-soluble protein and salt-soluble protein were obviously reduced, the proportion of alkali-soluble protein was increased greatly. The thermal stability of actin was batter than myosin.