Biomedical Engineering Reference
In-Depth Information
Table 6.1
Examples of bacteriocin applications in egg products
Bacteriocin treatment
Effect(s)
Reference(s)
Nisin
Decreased the decimal reduction
times (
D
-values) for
L. monocytogenes
in liquid whole egg
Knight et al.
1999
Schuman and
Sheldon
2003
Inactivation of
L. monocytogenes
in pasteurized liquid whole egg
Improves product shelf life,
inhibiting post-process proliferation of
L. monocytogenes
and
B. cereus
Nisin and PEF
Greater inactivation of
L. innocua
in liquid egg
Calderón-Miranda
et al
.
1999
Nisin and HHP
Greater inactivation of
L. innocua
and
E. coli
in liquid egg
Ponce et al.
1998
Nisin in polylactic acid (PLA)
coating
Inactivation of
L. monocytogenes
in liquid egg white
Jin
2010
Nisin plus allyl isothiocyanate
in PLA coating
Inactivation of a three-strain
S. enterica
cocktail in liquid egg white
Jin et al.
2013
was added at least 2 h before application of heat treatments (Knight et al.
1999
). In
spite of the fact that nisin is not active on Gram-negative bacteria, nisin addition also
increased the heat sensitivity of
Salmonella Enteritidis
PT4 in liquid whole egg and
in egg white during pasteurization (Boziaris et al.
1998
).
The presence of
B. cereus
in liquid egg can pose a serious hazard to the food
industry, since a mild heat treatment cannot guarantee its complete inactivation. In
one study, the effects of added nisin, lysozyme, or a combination of both antimicro-
bials on the lag phase of
B. cereus
inoculated in homogenized liquid egg samples
previously heated at 60 °C for 10 min to inactivate background microfl ora was
investigated. The combination of lysozyme and nisin delayed the average onset of
growth until 10 h at 25 °C or approximately 30 h in samples stored at 16 °C
(Antolinos et al.
2011
).
Bacteriocins have been tested in liquid egg in combination with pulsed electric
fi eld (PEF) and high hydrostatic pressure (HHP) treatments as a way to enhance
inactivation of microorganisms. Exposure of
Listeria innocua
to nisin after PEF
treatment at low temperature showed an additive to synergistic effect, depending on
the bacteriocin concentration and the electric fi eld intensity and number of pulses
(Calderón-Miranda et al.
1999
). PEF treatments sensitized
L.innocua
to further
exposure to nisin in liquid whole egg. The PEF treatment followed by the exposure
of
L. innocua
to nisin increased microbial inactivation compared to the inactivation
observed when the bacterium was subjected to PEF alone. The combined effect of
both factors (PEF treatment and nisin addition) was either additive or synergistic,
depending on the intensity of PEF treatments (Calderón-Miranda et al.
1999
).
Addition of nisin in combination with HHP treatment markedly reduced viable cell
counts of
Escherichia coli
and
L. innocua
in liquid whole egg (Ponce et al.
1998
). A
reduction of almost 5 log units in
E. coli
counts and more than 6 log units for
L.
