Kinetics of salmon quality changes during thermal processing

The kinetics of reactions leading to changes in salmon quality during thermal processing were evaluated. Small samples (D 30 mm × H 6 mm) cut from pink salmon (Oncorhynchus gorbuscha) fillets were sealed in aluminum containers (internal dimension: D 35 mm × H 6 mm) and heated in an oil bath at 100, 111.1, 121.1, and 131.1 °C for different time intervals up to 180, 150, 120, 90 min, respectively. A fractional conversion model was used to describe the increase in cook loss during heating; and a quadratic relationship to correlate cook loss with area shrinkage ratio. Color changes (CIE L∗, b∗ and ΔE) involved whitening and browning phases. In the browning phase, the changes of CIE L∗, b∗ and ΔE followed a zero-order reaction. The progressive change of texture with time as indicated by shear force during heating went through four different phases, and the second (rapid tenderizing) and third phases (slow toughening) were modeled using a first-order reaction kinetic model. The decay of thiamin during heating was modeled with two different relationships: a second-order reaction in which the temperature dependence of the rate constant followed an Arrhenius relationship; and a Weibull-log logistic model recently proposed.