Effect of temperature history on the growth of Listeria monocytogenes Scott A at refrigeration temperatures.
The effect of pre-inoculation temperature on the subsequent growth of Listeria monocytogenes Scott A at 5 degrees C was examined in microbiological medium, UHT milk, canned dog food, and raw ground beef (untreated and irradiation-sterilized). In microbiological medium, the duration of the lag phase was decreased when aerobic and anaerobic cultures were initially grown at less than or equal to 28 and less than or equal to 13 degrees C, respectively. Subsequent exponential growth rates and maximum population densities of the 5 degrees C cultures were not affected by temperature history. Differences in lag phase durations were also observed when L. monocytogenes initially cultured at 19 and 37 degrees C were grown at 5 degrees C in UHT milk and some of the canned dog food varieties. Growth of L. monocytogenes was not observed in either untreated or irradiation-sterilized raw ground beef. While temperature history can affect the growth kinetics of L. monocytogenes at 5 degrees C, it did not account for the lack of growth in raw meat, suggesting that there is an inhibitory condition or component in ground beef that is lost upon cooking.
Buchanan
R L
RL
Microbial Food Safety Research Unit, U.S. Department of Agriculture, ARS Eastern Regional Research Center, Philadelphia, PA 19118.
Klawitter
L A
LA
D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D003080:Cold Temperature; D015169:Colony Count, Microbial; D003470:Culture Media; D005514:Food Irradiation; D005516:Food Microbiology; D007700:Kinetics; D008089:Listeria monocytogenes / Q000254:growth & development*; D008460:Meat; D008461:Meat Products; D008892:Milk / Q000382:microbiology; D012034:Refrigeration; D013696:Temperature
D003470:Culture Media