Lethality of Beef Cooking Methods Against Pediococcus Species Surrogates of Shiga Toxin-Producing Escherichia coli

Abstract

Shiga toxin-producing Escherichia coli (STEC) outbreaks in Kenya are low in contrast to the United States, where the consumption of undercooked minced beef is implicated in 46% of all foodborne outbreaks. This study hypothesized that the negligible meat-borne STEC incidences in Kenya are attributed to the high-temperature long-time cooking styles of meat. For laboratory biosafety concerns, the study utilized a surrogate bacteria starter culture, Bactoferm LHP-DRY (Chr. Hansen, Denmark), as the preferred challenge organisms. Beef steak was cooked by boiling (95°C/1 h), simmering (85°C/1 h), roasting (163°C/1 h), pressure cooking (85 kPa/80°C/30 min), sous vide cooking to three degrees of doneness, that is rare (60°C), medium (71°C) and very well done (82°C) all for 1 h, and pan-broiling (163°C/6 min per side) for burger patties. The beef cooking treatments yielded endpoint core temperatures ranging from 94.3°C to 55.07°C (p < 0.05). The log reductions of the surrogate ranged from 2.83 to 5.23 cfu/g (p < 0.05). The highest lethality was observed in pressure cooking (5.23), very well done sous vide (5.13), oven roasting (4.83), medium done sous vide (4.13), and boiling (4.0 log reductions cfu/g). The conventional beef cooking methods utilized in Kenya, namely boiling, simmering, and roasting attained endpoint core temperatures greater than 71.1°C that guarantee the required instant 5-log reduction of Salmonella and STEC without requiring a dwelling or holding time. The study concluded that the high-temperature long-time beef cooking methods practiced in Kenya together with the Kenyan consumer preference for very well-done beef could explain the almost negligible reporting of meat-borne pathogenic E. coli O157:H7 human infections or outbreaks. This study recommended the sensitization of meat consumers on potential hazards in meat, with emphasis on high-temperature long-time cooking methods that assure safety. Additionally, the study recommends Good Hygiene Practices (GHP) and HACCP in slaughter operations that will guarantee meat safety and possibly render undercooked meat safe.