title: Effectiveness of inactivation of foodborne pathogens during simulated home pan frying of steak, hamburger or meat strips.
abstract: In order to evaluate the effect of simulated home pan frying of raw meat and meat preparations of different animal species on the thermal inactivation of pathogens, the heat resistance (D-value) of three strains of Campylobacter jejuni, Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and two strains of generic E. coli was validated in BHI and adjusted BHI (i.e. pH5.6 and 1.5% NaCl) at 60°C. The D-values were obtained of the linear phase of the survivor curves created in GInaFiT, a freeware tool to fit models to experimental data. The obtained D-values corresponded to those previously published in literature and confirmed L. monocytogenes to be the most heat resistant pathogen among them. Heat treatment in adjusted BHI significantly increased heat-resistance of E. coli O157:H7 and generic E. coli. Subsequently, the thermal inactivation of L. monocytogenes, Salmonella spp., C. jejuni and E. coli O157:H7 was evaluated using a standardized procedure simulating commonly used home pan frying of various types of meat including steaks or filets, hamburgers and meat strips from various animal species such as pork, beef, chicken, lamb and some turkey, horse, kangaroo and crocodile meat. Corresponding F70-values were calculated based upon measured core time/temperature profiles. It was noted that a core temperature of 70 °C was not always achieved and, moreover, a heat treatment equivalent to 2 min at 70 °C was also not always obtained. This was in particular noted in hamburgers although the meat was visually judged well done. On several occasions, residual survivors of the initial inoculated (4 logCFU/g) food borne pathogens could be recovered either by enumeration (limit of detection 1 logCFU/g) or by the presence/absence testing per 25 g. Pan frying of hamburgers yielded the highest number of surviving pathogenic bacteria (46%), followed by well-done filets and steaks (13%) and meat strips (12%). Taking only steaks (beef, horse, kangaroo, crocodile and turkey) into account, residual detection of pathogens occurred for all levels of doneness: 18% for well-done, 71% for medium and even 90% for rare steaks. Numbers of L. monocytogenes recovered after heat treatment ranged from <1 logCFU/g to 2.6 logCFU/g. Although, the prevalence of pathogens in meat might be low, and the numbers present in case of natural contamination are probably lower than the current used inoculum of 4 logCFU/g, consumers could still be exposed to surviving food borne pathogens in case of these commonly used pan frying of raw meat and meat preparations at consumer's home.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium. Electronic address: evy.lahou@ugent.be.
authors.forename: Evy
authors.initials: E
authors.lastname: Lahou
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Elien
authors.initials: E
authors.lastname: De Boeck
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Elien
authors.initials: E
authors.lastname: Verguldt
authors.affiliation: Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems (BIOSYST), Faculty of Bioscience Engineering, KU Leuven, Willem de Croylaan 42-box 2428, 3001 Leuven, Belgium.
authors.forename: Annemie
authors.initials: A
authors.lastname: Geeraerd
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Devlieghere
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Mieke
authors.initials: M
authors.lastname: Uyttendaele
mesh_terms: D000489:Alligators and Crocodiles; D000818:Animals; D058491:Bacterial Load; D018407:Bacterial Physiological Phenomena; D002417:Cattle; D002645:Chickens; D003296:Cooking / Q000592:standards; D005516:Food Microbiology; D006736:Horses; D006358:Hot Temperature; D008460:Meat / Q000382:microbiology*; D050296:Microbial Viability; D012756:Sheep; D013552:Swine; D014422:Turkeys
keywords: Heat inactivation; Home cooking practices; Meat and meat preparations; Pathogens