Microwave oven heating for inactivation of Listeria monocytogenes on frankfurters before consumption.
Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (<-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between > 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of <-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination.
Center for Meat Safety & Quality, Food Safety Cluster, Dept. of Animal Sciences, Colorado State Univ., Fort Collins, CO 80523, USA.
Mawill
M
Rodríguez-Marval
Ifigenia
I
Geornaras
Patricia A
PA
Kendall
John A
JA
Scanga
Keith E
KE
Belk
John N
JN
Sofos
D000085:Acetates / Q000737:chemistry; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry; D002417:Cattle; D015169:Colony Count, Microbial; D003296:Cooking / Q000379:methods; D005503:Food Additives / Q000737:chemistry; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000737:chemistry; D008089:Listeria monocytogenes / Q000254:growth & development / Q000528:radiation effects*; D008461:Meat Products / Q000032:analysis / Q000382:microbiology*; D008872:Microwaves; D013499:Surface Properties; D013552:Swine; D013997:Time Factors; D014871:Water Microbiology
D000085:Acetates; D000890:Anti-Infective Agents; D005503:Food Additives; D007773:Lactates