Biomedical Engineering Reference
In-Depth Information
Chapter 8
Biopreservation of Vegetable Foods
8.1
Application of Bacteriocins
8.1.1
Fresh Produce
Fresh produce products can become contaminated with human pathogenic bacteria
from different sources (such as manure, irrigation water, insects, and during har-
vesting and other process operations), and have been implicated in a number of
outbreaks (Lynch et al.
2009
). Several bacteriocin preparations (such as nisin,
pediocin, or enterocin AS-48) have been assayed for inactivation of foodborne
pathogenic or toxinogenic bacteria (such as
Listeria monocytogenes
,
Bacillus
cereus
, and
Bacillus weihenstephanensis
,
Escherichia coli
,
Salmonella
and other
enterobacteria) on the surfaces of fresh-cut vegetables and on sprouted seeds
(Galvez et al.
2008
; Randazzo et al.
2009
; Abriouel et al.
2010
) (Table
8.1
).
Bacteriocin treatments have also been proposed for decontamination of whole fruit
surfaces, and to avoid transmission of pathogenic bacteria from fruit surfaces to
processed fruits (Ukuku et al.
2005
; Silveira et al.
2008
), and to decrease bacterial
survival of bacteria on sliced fruit surfaces during storage.
Several studies have reported inactivation of human pathogenic bacteria in sal-
ads. Torriani et al. (
1997
) reported that salad vegetables treated with culture super-
natant of a
Lactobacillus casei
strain reduced the coliform count, but the presence
of a bacteriocin was not confi rmed. Randazzo et al. (
2009
) tested the effect of bac-
teriocin RUC9 from a wild strain of
Lactococcus lactis
(previously isolated from
minimally processed mixed salads) in minimally processed iceberg lettuce samples
artifi cially inoculated with a wild strain of
L. monocytogenes
during storage at 4 °C,
in comparison with commercial nisin. None of the bacteriocin treatments com-
pletely eliminate the pathogen on the produce, but RUC9 treatment achieved a
greater reduction of
L. monocytogenes
viable counts after 7 days of storage at 4 °C
compared to nisin (2.7 log units versus 1 log unit). It was suggested that treatment
with RUC9 bacteriocin could be used as sanitizer to improve microbial safety and
