Biomedical Engineering Reference
In-Depth Information
bacteria,
B. thermosphacta
B2 and
Carnobacterium
spp. 845 (Nattress et al.
2001
).
An estimated surface concentration of 130
g/cm
2
of each of the antimicrobials
effectively inhibited
B. thermosphacta
B2 on inoculated cores of fat and lean pork
tissue when the cores were incubated in vacuum packages for 6 weeks at 2 °C. Nisin
and mixtures of the two antimicrobials inhibited
Carnobacterium
spp. 845 so that
its numbers were at least 3 log units lower than untreated samples after 26 and
27 days incubation for APT broth and pork juice, respectively. On lean pork tissue,
numbers of
Carnobacterium
spp. 845 were signifi cantly lower when 260
ʼ
ʼ
g/cm
2
of
a 1:3 (w/w) ratio of nisin to lysozyme was introduced to the cores.
A mixture of lysozyme and nisin at a ratio of 3:1 (w/w) and at a surface concen-
tration of approximately 260
g/cm
2
was effective in controlling the growth of lactic
acid bacteria (Nattress and Baker
2003
). Sensory evaluation of the loins showed no
difference between treated and untreated samples, but aerobically displayed chops
treated with antimicrobial had more prevalent off-odours and reduced odour accept-
ability than untreated samples. According to Branen and Davidson (
2004
) when
lysozyme is combined with ethylenediaminetetraacetate (EDTA), the antibacterial
spectrum increases signifi cantly and it is effective against Gram negative organisms.
The inhibitory effect of Microgard
TM
100, Microgard
TM
300, nisin, Alta
TM
2002,
Perlack 1902, sodium lactate and essential oil of mustard on experimentally inocu-
lated microorganisms was screened in an acidifi ed chicken meat model (Lemay et al.
2002
). Sodium lactate was found most effective against
B. thermosphacta
. Essential
oil of mustard lowered the aerobic mesophilic bacteria and lactic acid bacteria sig-
nifi cantly with respect to control after 2 days of storage. The other antimicrobial
agents tested had no signifi cant effect on the aerobic mesophilic bacteria,
E. coli
,
B. thermosphacta
and lactic acid bacteria counts, when compared to the control.
The antilisterial effi cacy of chitosan-coated plastic fi lms alone or incorporating
fi ve generally recognized as safe (GRAS) antimicrobials viz., nisin, sodium lactate
(SL), sodium diacetate, potassium sorbate (PB) and sodium benzoate (SB) in ham
steaks stored at room temperature for 10 days was evaluated (Ye et al.
2008a
).
Incorporating antimicrobials into chitosan-coated plastic fi lms slowed down or
inhibited the growth of
L. monocytogenes
. The chitosan-coated plastic fi lm contain-
ing SL was the most effective antimicrobial fi lm against
L. monocytogenes
. The fi lm
showed excellent longterm antilisterial effect with the counts of
L. monocytogenes
being slightly lower than the initial inoculum.
The antimicrobial effect of thyme essential oil (EO), nisin, and their combina-
tion, on
E. coli
O157:H7 was examined in both tryptic soy broth (TSB) and minced
beef meat (Solomakos et al.
2008
). A 0.6 % of EO was found suitable for the prod-
uct and further examined against the pathogens in minced meat. Treatment of
minced beef meat with EO showed an inhibitory activity against
E. coli
O157:H7
during storage at 10 °C, but not at 4 °C. Treatment of minced beef meat or TSB with
nisin did not show any antibacterial activity against
E. coli
O157:H7. The combina-
tion of 0.6 % EO and 500 or 1,000 IU/g nisin showed an additive effect against the
pathogen, which was higher during storage at 10 °C than at 4 °C. The inhibitory
effect of essential oils (EOs) extracted from the aerial parts of cultivated
Salvia
offi cinalis
L. and the berries of
Schinus molle
L. were evaluated against two foodborne
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