Biomedical Engineering Reference
In-Depth Information
to reduce maximum
Listeria
counts by 1-3 log units in an artifi cially inoculated
surubim. In another study, when an “alecrim pimenta” extract was tested in combi-
nation with strains of
Carnobacterium maltaromaticum
(bacteriocinogenic or not),
variable effects were observed on
L. monocytogenes
(dos Reis et al.
2011
), ranging
from strong inhibition to only transient inhibition, depending on the substrate (suru-
bin broth, or surubin homogenate). It was concluded that the use of alecrim pimento
extract and cultures of carnobacteria have potential to inhibit
L. monocytogenes
in
fi sh systems and the applications should be carefully studied, considering the infl u-
ence of food matrix.
Experimental work carried out with bacteriocin-producing lactobacilli indicates
that these bacteria can inhibit
L. monocytogenes
in seafood products. Cultures of
L. sakei
L6790 (producer of sakacin P) inoculated on CSS only had a bacteriostatic
effect on
L. monocytogenes
, similarly to an isogenic (bac
−
)
L. sakei
strain. However,
application of the bacteriocinogenic culture in combination with a sub-lethal con-
centration of purifi ed sakacin P resulted in a partial inactivation of
L. monocyto-
genes
population (Katla et al.
2001
). In another study, the bacteriocinogenic strain
L. curvatus
CWBI-B28 was tested against
L. monocytogenes
in CSS during storage
at 4 °C by using different approaches: producing bacteriocin
in situ
, spraying with
partially purifi ed bacteriocin, packaging in bacteriocin-coated plastic fi lm, and cell-
adsorbed bacteriocin (a suspension of producer cells on which maximum bacterio-
cin has been immobilized by pH adjustments) (Ghalfi et al.
2006
). In spite of the
fact that all different treatments achieved some inactivation of
L. monocytogenes
in
CSS, the cell-adsorbed bacteriocin provided best results, with complete inactivation
of listeria for up to 20 days (Ghalfi et al.
2006
). Vescovo et al. (
2006
) evaluated the
biopreservative potential of three antimicrobial-producing LAB strains (
L. casei
,
L. plantarum
and
C. piscicola
) on refrigerated CSS stored under vacuum. All three
strains were able to inhibit growth of
L. innocua
and none affected negatively the
sensory quality of the product. The combination of
L. casei - L
. plantarum
was the
most effective in inhibition of
Listeria
, while a
L. casei
-
C. piscicola
association
was less effective than
C. piscicola
alone (Vescovo et al.
2006
). In another study,
bacteriocin-producing LAB (
E. faecium
ET05,
L. curvatus
ET06,
L. curvatus
ET30,
L. delbrueckii
ET32 and
P. acidilactici
ET34), selected by their capacity for growth
and producing inhibition in vitro under conditions simulating cold-smoked fi sh (at
high salt-on-water content, low temperature and anaerobic atmosphere) were inocu-
lated onto salmon fi llets in co-culture with
L. innocua
2030c, and cold-smoked
processed. The fi nished product was then packed under vacuum and stored at 5 °C
(Tomé et al.
2008
).
L. curvatus
ET30 and
L. delbrueckii
ET32 showed a good bio-
preservation potential for CSS, while
L. curvatus
ET06 and
P. acidilactici
ET34
showed a bacteriostatic mode of action against the target bacteria in vitro as well as
when inoculated into the salmon fi llets. Comparatively, strain
E. faecium
ET05
showed the best results in controlling
L. innocua
growth in vacuum-packaged CSS
processed under the salting/drying/smoking.
Bioprotective cultures can also be applied during the dry-salting process. For
example, commercial preparations of
P. acidilactici
(Fargo-35, Laboratorios
Amerex S.A., Madrid, Spain),
L. curvatus
(InhiList-2, Innaves S.A., Pontevedra,
