Application of high hydrostatic pressure for the reduction of STEC on raw ground beef patties and its impact on physicochemical properties: pH and color

This study on raw ground beef patties evaluated: resistance of STEC strains inoculated at 6 log CFU/g (O157:H7, O26, O45, O103, O111, O121, and O145) subjected to 350, 450 and 600 MPa, for 5 min at 10 °C; effectiveness of pressure for initial loads (2, 3 and 4 log CFU/g) of O157:H7; and general impact of high hydrostatic pressure (HHP) on raw patties. For 600 MPa treatments and 6 log CFU/g load of STEC, ~5 log CFU/g reductions were obtained with all strains. For 450 MPa, differences in baroresistance among strains became evident. When inoculating O157:H7 at different loads, counts after 600 MPa fell below quantification limits, though virulence genes were detected for the two highest loads. Additionally, HHP reduced native aerobic microbiota to