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Cooked pork chops may still contain Listeria, Salmonella pathogens
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Only cooking pork meat to well-done temperatures — not to rare or medium-level temperatures — in a static oven fully eliminated Salmonella and Listeria pathogens, according to findings published in Risk Analysis.
“Pork meat, like loin chop, must be cooked before consumption. It is generally accepted that when meat is subjected to a core temperature of 70°C for 2 minutes or to a heat treatment equivalent to 2 minutes at 70°C, it will accomplish a substantial inactivation of pathogens,” Alessandra De Cesare, PhD, professor in the department of agricultural and food sciences at University of Bologna in Italy, and colleagues wrote. “However, if a few pathogen cells persist during and after cooking, they might be able to multiply during storage in the refrigerator and when meat is left at room temperature.”
The degree of cooking and storage of leftovers impact the microbiological safety of pork meat. Factors like moisture, water activity, fat levels, salts, carbohydrates, pH and proteins affects the cooking treatment and effectiveness on bacteria survival. Researchers experimentally contaminated 160 packs of loin chop with 10 million cells of L. monocytogenes and Salmonella to examine the pathogen levels in cooked pork. They divided the samples to be cooked to rare, medium and well-done by gas on a non-stick pan or in a static oven. A total of 240 cooking tests were completed, with 40 repetitions for each cooking combination. De Cesare and colleagues interviewed 40 people aged 20 to 60 years to determine how household consumers preferred their meat cooked and meat storage practices.
The results showed that only well-done pork cooked in a static oven completely inactivated the tested pathogens. When each of the tested cooking treatments were applied with product temperatures of 73.6°C or higher, only then did the meat reach a reduction between one and 10 million of pathogen cells. In total, the mean level of exposure to Listeria and Salmonella was one cell per each gram of meat at the time of consumption.
According to simulation results, the few surviving cells can multiply during storage in the refrigerator and at room temperature, with probabilities of 0.059 and 0.035 for L. monocytogenes and 0.049 and 0.031 for Salmonella for all combinations excluding well-done meat cooked in an oven. These findings suggest that the final temperature necessary to inactivate pathogens should be considered before consuming pork meat.
“The results of this research show the inactivation dynamic of L. monocytogenes and Salmonella associated with different cooking scenarios as well as the impact of meat leftover storage on human exposure to those pathogens,” De Cesare and colleagues wrote. “The results obtained can be directly implemented in risk assessment models and guidelines for consumers on practices to follow in order to manage cooking of pork meat at home.” – by Savannah Demko
Disclosures: Infectious Diseases in Children was unable to confirm relevant financial disclosures at the time of publication.
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