4 °C - the National Sea Grant Library

Part II Evaluation of the cooling process.
Air cooling of atmospheric steamed crab meat was accomplished by
transferring meat from perforated s.s. trays on exit from the tunnel to solid s.s. trays.
This transfer resulted in a temperature drop of 15°C from exit temperatures. Allowing
the meat to cool in the tray for an additional l0-15 minutes prior to packing further
lowered meat temperature depending upon the relative thickness of the sample. Hotfilled
crab meat was immediately packed into plastic cups after transfer (not allowed
to air cool) to the solid S.S. trays.
Figure 3 shows cooling rate differences between air-cool and hot-fill packing
of crab meat after placing on ice. Both samples rapidly cooled to below 37.7°C in less
than one hour and were virtually identical (14.5°C) after two hours on ice. The
primary difference observed was the initial cooling rate. Even though the two packing
techniques yielded only a small difference in cooling time, the results are significant.
Further studies were conducted to simulate conditions where crab meat would be
directly filled into containers from the end of the tunnel without handling. This
packing technique would minimize exposure of crab meat to environmental conditions
in the packing room.
Figure 3. Air-cool vs. Hot-fill Pack
0 15 30 45 60 75 90 105 120 135 150 165 180
Time (min)
4 Hot-fill 8 Air-cool
By using a mathematical spreadsheet and model generator, cooling times for
- initial temperatures outside the experimental conditions could be approximated. This
task was accomplished by noting trends in cooling rate constants observed for initial
meat temperatures. These trends were used as a base line and extrapolated in order
to achieve a good estimate on rate constants at higher initial temperatures. Figure 4
shows that as the initial meat temperature increases, a rise in the rate constant occurs
resulting in a drop in time to reach a specified temperature.