Response of four types of coliphages to high hydrostatic pressure

Pressure inactivation of four types of coliphages, ϕX 174 (ssDNA virus), MS2 (ssRNA virus), λ imm434 (dsDNA virus) and T4 (dsDNA virus), was studied to evaluate their potential as human enteric viral surrogates for use in validation of commercial pressure processing treatments. Phage ϕX 174 demonstrated an unexpected high resistance to pressure with no more than 1-log10 reduction observed following exposures to 350-600 MPa. There was no greater than 1-log10 reduction below 500 MPa for MS2 in modified phosphate-buffered saline, but a 3.3-log10 reduction was observed for MS2 pressurized at 600 MPa. Coliphages λ imm434 and T4 were relatively sensitive to pressure in demonstrating inactivation at 350 MPa. At 21 °C, λ imm434 was inactivated in modified phosphate-buffered saline or Dulbecco's Modified Eagle's Medium plus 5% fetal bovine sera by at least 7.5-log10 when exposed to 400 MPa for 5 min. Treatment at 450 MPa for 5 min was necessary to obtain a log10 reduction of 6-7 for T4.