2.2. Cooling curves
Cooling curves were obtained using two household refrigerators:(1) a domestic refrigerator (DC49A, Eletrolux, Curitiba,Brazil) with a freezing compartment, static cooling and no ‘‘quickfreeze’’ function, which was named ‘‘Freezer A’’ and (2) a second freezer (FFE24, Electrolux, Curitiba, Brazil) with a ‘‘quick freeze’’compartment equipped with a forced-air cooling system denoted as ‘‘Freezer B’’. When the quick freeze function was enabled, thefreezer worked with no interruption and the temperature dropped quickly to lower temperatures than conventional freezers. Freezer A had a total volume of 115 L and a freezing capacity
2.3. Freezing time and freezing rate The freezing time was obtained from the cooling curves and
was established according to the time for the central temperature of the sample to decrease from 0 to _5 _C (critical zone of maximalice crystal formation) and from 0 to _18 _C (almost complete freezing), as Chen and Pan (1997). Freezing rates were calculated as the half thickness of the fish burger