| The thermal property parameters of fresh water fish muscle such as the freezingpoint, the apparent specific heat, and the enthalpy during low temperature phasetransition (-40℃～10℃) were important datum which were applied to calculate thefreezing processing time, analyze the changes of the energy and quality during freezing(or thawing) phase transition, determine the optimum technics of the freezing (orthawing). Those properties during low temperature phase transition (-40℃～10℃) weredetermined by Differential Scanning Calorimetry (DSC), and influences of the sodiumchloride, sucrose and mixture of them on the thermal properties and proteinthermostability of fresh water fish muscle were studied, and the thermal parametersmodels during phase transition were established which were applied to the cryogenicengineering, and the freezing processing temperature and time of the silver carp musclein -18℃was simulated. The research results were as follows:1. The freezing phase transition area and enthalpy of four species of fresh water fishmuscle were -17℃～-11℃and -212 J/g～-184 J/g, and the thawing phase transition areaand enthalpy of fresh water fish muscle were -2.8℃～0.0℃and 191 J/g～212 J/g,respectively. Temperature of freezing point, completely frozen the apparent specific heat(-40℃), completely thawed the apparent specific heat (10℃) and the peak value ofapparent specific heat were -0.33℃～-0.83℃,1.57 J/g·℃～2.36 J/g·℃, 3.70 J/g·℃～3.76J/g·℃and 107 J/g·℃～130 J/g·℃respectively.2. The linearity assembled freezing point predictive model based on water-solubilitycontent, two segment apparent specific heat model and enthalpy model deduced fromapparent specific heat model were well established for fresh water fish muscle duringlow temperature phase transition. The freezing point and apparent specific heat above thefreezing point were influenced by water content, soluble solid content, protein contentand fat content significantly, and the enthalpy and apparent specific heat under thefreezing point was only influenced by temperature.3. Effects of the adding amount of the sodium chloride and sucrose on thermalproperties of the fresh water fish muscle were investigated. With the sucrose and thesodium chloride added to the fish flesh muscle, the unfreezable water content increased,which resulted in the shift of the freezing or melting phase transition area to lowertemperatures, and the phase transition enthalpy, the completely melted apparent specificheat (10℃) and the apparent specific heat maximum value all were reduced gradually, while the completely frozen apparent specific heat (-40℃) were increased. The sodiumchloride and sucrose reduced the energy that the melt needed during the entire phasetransition area (-40℃～10℃), which was more advantageous to thawing. The freezingpoint, the phase transition enthalpy and the apparent specific heat were influenced by theadding amount of the sodium chloride, the additive sucrose, the soluble solid content, themoisture content and the unfreezable water content significantly, and the influence of theadding amount of the sodium chloride was most significant.4. Effects of the sodium chloride and sucrose on the protein thermotropy of thesilver carp muscle were investigated. Myosin, sarcoplasmic proteins and actindenaturation temperatures of the silver carp muscle were 41.50℃, 53.28℃and 72.4℃,respectively, and their denaturation enthalpy were 0.125 J/g, 0.73 J/g and 0.33 J/g,respectively. After addition of the sucrose, the transition temperatures shifted to highertemperature, enhancing the protein thermostability; while addition of the sodium chlorideleaded to the shift of the transition temperatures to lower temperature, decreasing theprotein thermostability; After addition of the sucrose-NaCl compound, the proteindenatured temperature were mainly influenced by the sodium chloride. With the sodiumchloride and the sucrose added to the fresh water fish muscle, the protein of accessibilitywater was descended, and the denaturation enthalpy was decreased.5. The dynamic thermal property parameters were applied to establish unified gridenergy separating equation during the fish muscle freezing region by the enthalpy law,and the silver carp muscle freezing process in -18℃was simulated. The simulationfreezing time and speed relative error were 1.54% and 2.33% respectively, and the resultshowed the freezing process for the silver carp meat in -18℃was well simulated.
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