Agriculture Reference
In-Depth Information
Gleeson and O'Beirne (
2005
) investigated the inoculation of sliced carrots (with
blunt or sharp machine blade and a razor blade) with
E. coli
and
L. innocua
and
storage under passive MAP (8 °C). They found that
E. coli
counts on razor sliced
carrots were approximately 1 log cycle lower than counts on the blunt or sharp
machine blade sliced carrots. Subsequently,
E. coli
survived better on carrots sliced
with blades that caused the most damage to cut surfaces.
Gomez-Lopez et al. (
2007a
) monitored the effect of gaseous chlorine dioxide
treatment in conjunction with MAP (4.5 % O
2
+ 8.9 % CO
2
) to reach shelf life exten-
sion of grated carrots stored at 7 °C. After ClO
2
treatment, the decontamination
levels (log CFU/g) obtained were 1.88, 1.71, 2.60, and 0.66 for mesophilic aerobic
bacteria, psychrotrophs, lactic acid bacteria (LAB) and yeasts, respectively. The
treated samples showed yeast counts that were initially only minimally reduced
with respect to the untreated ones, and reached the same level on the fi fth day
(Table
1.1
).
The survival of inoculated
S. enteritidis
and
L. monocytogenes
on shredded car-
rots under MAP (2.1 % O
2
/4.9 % CO
2
, 5.2 % O
2
/5 % CO
2
) at 4 °C was analyzed by
Kakiomenou et al. (
1998
). Even though both pathogens survived they did not grow
regardless of the packaging system used. It was detected that numbers of total viable
counts (TVC) and LAB were always lower in samples stored under MA conditions
than in those stored aerobically.
Grated carrots, inoculated with
E. coli
(6 log CFU/g) and stored at 4 ± 1 °C were
used to assess the effi ciency of gamma irradiation (doses from 0.15 to 0.9 kGy) in
conjunction with MAP (60 % O
2
+ 30 % CO
2
) by Lacroix and Lafortune (
2004
).
Inoculated
E. coli
was completely eliminated at doses
0.3 kGy in samples treated
under MAP. A 4 and 3 log reduction in samples treated under MAP and under air
was reported.
Carrots were washed in hydro-alcoholic solution (30 % v/v in ethanol), coated
into a sodium alginic (4 % w/v) water solution and then washed again in the alco-
holic solution and subsequently stored under both PMAP (PP fi lm with OTR:
2,076.9 cm
3
/m
2
day) and AMAP (10 % O
2
/10 % CO
2
) at 4 °C. Lag phase of micro-
bial population on coated samples was extended with cell loads remaining stable at
3 log CFU/g for the initial 7 days. Combination of both PMAP and AMAP and
coating of carrots offered a shelf life extension of 12 days compared to control
(Mastromatteo et al.
2012
).
Pilon et al. (
2006
) investigated carrots stored under air, vacuum and MA condi-
tions (2 % O
2
+ 10 % CO
2
) at 1 ± 1 °C for 21 days (LDPE-BOPP fi lm). Average val-
ues recorded for pH ranged from 6.2 to 6.5 for minimally processed carrot, over
different storage periods, whereas vitamin C remained intact up to 21 days of stor-
age. For the minimally processed carrot, faecal and total coliforms, anaerobic meso-
philes and
Salmonella
could not be detected in any of the treatments.
Grated carrots stored in air, MA (2.1 % O
2
, 4.9 % CO
2
) were used to monitor the
fate of inoculated
Salmonella enteritidis
and vacuum at 4 °C to trace the presence of
Lactobacillus
irrespectively of the size of its inoculum. As Tassou and Boziaris
(
2002
) pointed out, acetic acid was produced mostly under modifi ed atmosphere in
comparison with samples stored under vacuum or aerobic conditions.
≥
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