Effect of electron beam irradiation on minas frescal cheese artificially contaminated with Shiga toxin-producing Escherichia coli O157:H7

Abstract

Minas frescal cheese (MFC) is a potential vehicle for Shiga toxin-producing Escherichia coli (STEC) O157:H7. The effect of electron beam irradiation on the control of STEC O157:H7 in artificially contaminated MFC (5 log cfu g−1) was evaluated. Samples were irradiated at doses of 1.0, 1.5, and 2.0 kGy and evaluated for 40 days at 4 °C. Shelf life extension and the stability of the lipid fraction of the cheeses were also evaluated. At a dose of 1.0 kGy, STEC O157:H7 was reduced by 3 log cfu g−1, while at 1.5 and 2.0 kGy, STEC O157:H7 was eliminated. Shelf life extension, measured by the count of total aerobic bacteria (TAB), occurred in up to ten days. Irradiated and non-irradiated samples were affected by lipid oxidation. Electron beam irradiation proved to be a viable technology and a good alternative to guarantee the quality and control of STEC O157:H7 in the MFC.