Rosmarinus was less effective than the other EOs against both
Listeria and Staphylococcus, although it was able to reduce bacterial
number according to Fern
andez-Lopez et al. (2005) and Skandamis
and Nychas (2001), thanks to the presence of 1.8 cineol (43.9%) and
a pinene (11.5%) (Table 1) (Burt, 2004; Lv et al., 2011). Both concentrations
0.5 and 1% (v/w) caused bacteriostasis on all the
pathogen concentrations (regression line slope coefficients of the
curves were all near zero), even in the more concentrated dilution
(DIL 1) of the pathogens. In particular, the 1% concentration showed
bactericidal activity against DIL 4 of Staphylococcus after 14 days of
preservation. Rosmarinus at 2% (v/w) caused a slight and gradual
reduction (time-dependent) of the microbial load of the three
higher Listeria concentrations and represented the MIC100 for DIL 4
after 11 days of preservation at 4 C (Table 8). The regression line
slope coefficients of the time trend curves of each bacteria had
negative values, thus indicating a general decrease of the microbial
load; moreover, their absolute values had increasingly large values
going from DIL 1 to DIL 4, showing the increase of the EO action
with the decrease of the pathogen concentration. MBC90 and
MBC100 determination was possible only for the lowest bacterial
concentrations, respectively after 11 and 14 days of preservation for
Listeria and Staphylococcus