3.1.2. Gram negative counts
Except for the PVC treatment, GN remained less than 4.00 log
CFU/g for all treatments through 25 day storage (Table 1). The PVC
treatment increased to 4.65, 4.41 and 4.51 log CFU/g on day 5 for
ground beef formulated with 10, 20 and 30% fat, respectively. The
GN counts were higher for 10 and 30% ground beef packaged in
PVC on day 7 when compared to all MAP and VP treatments, which
suggested that exposure to oxygen in the PVC treatments promoted
the growth of Gram negative microorganisms. The GN counts were
similar (P N 0.05) for MAP and VP treatments during storage and revealed
that both packaging methods (MAP and VP) exerted bacteriostatic
effects on GN microorganisms by reduction of oxygen in the
packages. The increase (P b 0.05) in all PVC treatments on day 5
and decrease on day 7was indicative of themicroorganisms entering
the stationary growth phase. In general the GN bacteria represented
approximately 40% of the total aerobicmicroflora on days 14 through
25.