Effects of High Hydrostatic Pressure and Beef Patty Formulations on the Inactivation of Native Strains of Shiga Toxin-Producing Escherichia coli O157:H7

This study aimed to evaluate the effects of beef patty formulations and pressure levels on the inactivation of spoilage microbiota and native Shiga toxin-producing Escherichia coli (STEC) O157:H7. Beef patties were made with different salt and fat content (A: 1% NaCl - 10% fat, B: 2% NaCl - 10% fat, C: 1% NaCl - 20% fat and D: 2% NaCl - 20% fat) and treated at 400 and 600 MPa. STEC reductions after 400 and 600 MPa were 2 and 4 log CFU/g, respectively. STEC inactivation was similar in patties with 10 and 20% of fat content. However, patties with 1% of NaCl showed higher STEC reductions than those made with 2% of NaCl. The baroprotective effect of salt was probably related with the accumulation of compatible solutes, a well-known bacterial response to osmostress. After HPP treatment, all counts of spoilage microbiota were under the detection limit regardless of the formulation.

Automated summary

This study demonstrated that the salt content and pressure levels in beef patty formulations have an impact on the inactivation of STEC. Beef patties with 1% salt content showed higher reductions in STEC, whereas patties with 10% and 20% fat content had similar STEC inactivation effects. After HPP treatment, the spoilage microbiota counts were below detection limit, regardless of the formulation.