Biomedical Engineering Reference
In-Depth Information
(Ananou et al.
2005a
,
b
). Further the effectiveness of enterocin AS-48 alone or in
combination with chemical preservatives and/or heat against
L. monocytogenes
and
S. aureus
in a cooked ham model system was tested by same workers (Ananou et al.
2010
). AS-48 alone was effective against
L. monocytogenes
at 5 and 15 °C, but it
was not suffi cient to avoid regrowth of
Listeria
during the 60 days storage. However,
combination of AS-48 with nitrite/nitrate, pentasodium tripolyphosphate, sodium
benzoate or potassium sorbate improved the effectiveness and the most suitable
combination was AS-48-nitrite/nitrate (0.007 %) that reduced
Listeria
below detec-
tion level from the beginning to end of storage. Much more resistant,
S. aureus
was
also inhibited by AS-48 alone at 5 °C, and especially in combinations with nitrite/
nitrate, pentasodium tripolyphosphate, sodium lactate and sodium acetate. Best
results against both the pathogens were obtained when sodium pyrophosphate was
applied in combination with 60
g g
−1
AS-48. Sub-lethal heat (60 °C, 2 min) clearly
increased AS-48 activity against both
Listeria
and
Staphylococcus
.
In another trial enterocin CCM 4231 was added (12,800 AU/g) during prepara-
tion of dry fermented Hornad salamis artifi cially inoculated with 1 % of a
L. mono-
cytogenes
culture, containing approximately 10
8
cfu/ml. After 3 weeks of ripening,
the count of
L. monocytogenes
was 10
4
cfu/g in samples with added enterocin as
compared with 10
7
cfu/g in control samples (Lauková et al.
1999
). The anti-listerial
effect was examined for enterocins A and B in selected meat and meat products
(cooked ham, minced pork meat, deboned chicken breasts, pate and slightly fer-
mented sausages) stored at 7 °C (Aymerich et al.
2000
). A reduction in the counts of
artifi cially inoculated
L. innocua
was observed in all the samples during storage, as
compared with control treatments where the counts either increased or remained
constant during storage. Similar anti-listerial activity was also noted for enterocins
1071A and 1071B, produced by
E. faecalis
BFE 1071, in fi sh spread. More than
90 % reduction in the counts of
L. innocua
was found after 21 days of storage under
refrigerated conditions, when compared with untreated control (Dicks et al.
2006
).
The effect of different nisin concentrations on
L. monocytogenes
in experimentally
contaminated Turkish fermented sausage (
sucuk
) was observed (Hampikyan and
Ugur
2007
). No
L. monocytogenes
surviving cells were detected in groups which
contained 100
ʼ
ʼ
g/g and 50
ʼ
g/g nisin at day 20 and 25, respectively.
Natural antimicrobials in raw products
: Lactoferrin, an iron binding protein, has
the potential to be an antimicrobial in foods (Naidu
2002
). An investigation was
made to observe the potential of “activated lactoferrin” as a spray treatment on car-
casses or on chilled primal cuts as a microbial blocking agent. It was found that
activated lactoferrin has activity against an array of bacterial pathogens including
E.
coli
O157:H7,
L. monocytogenes
,
Salmonella
spp., and
Campylobacter
, as well as
some meat spoilage organisms including
Pseudomonas
spp. and
Klebsiella
spp.
(Naidu
2002
). Lysozyme is one of the most frequently used antimicrobial enzymes
and shows antibacterial activity, mainly on Gram-positive bacteria by splitting the
bonds between N-acetylmuramic acid and N-acetylglucosamine of the peptidogly-
can in cell walls (Güçbilmez et al.
2007
). The antimicrobials lysozyme, nisin, and
mixtures of the two were used to control the growth of the meat-borne spoilage
