The bacteria were then sedimented by
centrifugation (1200 g, Hermle Model Z206A, Hermle Labortechnik,
Germany) and resuspended in an equal volume of sterile
0.1% peptone water (SPW, BD-Difco). Thawed ground beef (10 g)
was aliquoted into 2 oz. Nasco (Ft. Atkinson, WI) Whirl-Pak bags,
inoculated with 0.1 ml of STEC, mixed manually for 30 s, and then
sealed using the Multi-Vac A300 Packager. The final concentration
of STEC in the ground beef was ca. 8 log CFU/g. The sample bags
were then sealed in a second bag and stored at 4 C until HPP
treatment.