Thermal Food Processing

Thermal Processing of Poultry Products 207
Gande and Muriana 46 recorded a 1.25 to 3.5 log reduction in L. monocytogenes
populations following a prepackaging surface pasteurization treatment (60
to 120 sec at 246.1 to 398.9°C) of a fully cooked meat product removed from
its primary packaging wrap. When the turkey bologna was subjected to both a
pre- (60 sec) and postpackaging (45 or 60 sec) pasteurization process, they
detected a 2.7 to 4.3 log reduction in L. monocytogenes populations. These
relatively low log reductions for the time used for surface pasteurization can
be explained by the relatively large meat mass compared to individual slices. The
effect of thickness on heat penetration is well documented, but the effect of sample
thickness on surface heating rate is less well documented. Mangalassary et al. 47
found that thicker and higher fat turkey bologna samples had slower surface
heating rates than thinner and lower fat samples. For example, at 80°C the inpackage
pasteurization times for a 5 log reduction of L. monocytogenes on the
surface of turkey bologna were 0.72, 4.56, and 7.12 min for 4-, 12-, and 20-mmthick
samples. 47 The rates of surface heating for 4-, 12-, and 20-mm-thick bologna
in the package are shown in Figure 7.1.
7.2.2.2 Regulations for Packaged Ready-to-Eat Poultry Meat
The U.S. regulations governing the thermal processing of ready-to-eat meats have
evolved from a specific endpoint temperature requirement to a lethality requirement.
This evolution roughly follows the move from a USDA inspection-based meat and
poultry processing system to a food processing-derived HACCP-based program.
Thus responsibility for documenting the safety of food products has shifted from the
government to the processor. The 1999 USDA-FSIS ruling (CFR 381.150) specified
a lethality of heat treatment for ready-to-eat whole muscle poultry meat of 7.0 log 10
Temperature ( O C)
60
55
50
45
40
35
30
25
20
15
10
5
4cmthick
12 cm thick
20 cm thick
0 100 200 300
Time (s)
400 500 600
FIGURE 7.1 Meat thickness effect on surface heating rate in a 60°C water bath for inpackage
pasteurized bologna.