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Quality predictive models were developed to predict the freshness of bighead carp (Aristichthys nobilis) fillets during storage at different temperatures. Quality indices [sensory score, total volatile base nitrogen (TVB-N), total aerobic counts (TAC) and K value] at )3, 0, 3, 9 and 15°C were estimated and kinetically modelled by the Arrhenius equation. The activation energy (E A ) of sensory score, TVB-N, TAC and K value was 78.17, 75.93, 106.53 and 76.21 kJ mol )1 , and the corresponding rate constants (k 0 ) were 1.16 · 10 15 , 2.60 · 10 14 , 4.05 · 10 19 and 1.36 · 10 15 . The high regression coefficients (R 2 > 0.87) indicated the acceptability of the zero-order reaction for sensory score, TVB-N, TAC and K value. Relative errors between predicted and observed freshness indicators values of sensory score, TVB-N, TAC and K value were all below 10% except the values at 6th day of K value, 3rd day and 9th day of TVB-N. These results indicated that the models based on sensory score, TVB-N, TAC and K value could effectively predict the freshness indicators of bighead carp fillets at the range of )3 to 15°C.

In order to estimate the physicochemical changes of silver carp (Hypophthalmichthys molitrix) during 72 h post-mortem process at 0 • C, K-value, texture parameters, pH value, L * value, water holding capacity, cooking loss, salt-soluble protein, and electrical conductivity were studied. The highest inosine monophosphate concentration measured in silver carp occurred at 48 h and the lowest pH was reached at 12 h after slaughter. Adenosine triphosphate concentration, hardness, gumminess, and resilience within two hours and water holding capacity within four hours increased significantly (P < 0.05), and then decreased during post-mortem process. K-value and electrical conductivity increased as post-mortem process progressed while L * value and salt-soluble protein decreased. High correlations between electrical conductivity and biochemical/physical parameters were obtained. It was better to process silver carp in two to four hours after slaughter and electrical conductivity can be used as a rapid indicator to evaluate post-mortem change of silver carp within a certain period.

The changes in sensory assessment (SA), total aerobic counts (TAC), total volatile basic nitrogen (TVB-N), K value and electrical conductivity (EC) of allogynogenetic crucian carps (Carassius auratus gibelio) during chilling storage were determined. To evaluate the multiquality of allogynogenetic crucian carps, a Global Stability Index (GSI) method was developed with SA, TAC, TVB-N and K value. Then, predictive models of GSI and EC were established in combination with zero-order kinetics and Arrhenius equation. The results showed goodness of fit (R 2 > 0.97). The activation energies (EA) of GSI and EC models were 79.078 kJ/ mol and 80.595 kJ/mol, while the corresponding preexponential constants (k0) were 7.238 × 1013 and 2.466 × 1016, respectively. Relative errors between observed and predictive values of GSI and EC were within ±7% (12 days of storage) and ±0.6% (15 days of storage), respectively. Consequently, kinetic models based on GSI and EC can forecast the quality of allogynogenetic crucian carps during chilling storage. PRACTICAL APPLICATIONSThe allogynogenetic crucian carp is one of the crucian carp species with superiority in both production and genetic stability and is usually perishable during storage. Low temperature storage is a primary method to maintain fish freshness. It is meaningful to research the cold chain and try to predict the freshness of allogynogenetic crucian carps rapidly. Kinetic model is usually used in food quality prediction. Global Stability Index (GSI) is an index that can check the quality of food comprehensively, while electrical conductivity (EC) is widely used in determining meat and fish quality rapidly and economically. This work is to establish kinetic models based on GSI and EC to forecast allogynogenetic crucian carps' freshness and compare between EC and GSI to tick out which one is more suitable to predict the freshness of allogynogenetic crucian carps in cold chain circulations.