Agriculture Reference
In-Depth Information
1.7
MAP Application on Vegetables
1.7.1
Roots
1.7.1.1
Lotus
Lotus roots were treated with chitosan coating and subsequently stored under MAP
at 4 °C for 10 days.
L
* values of treated samples differed signifi cantly from the
control (68.8 and 48.9 for treated and control samples, respectively after 8 days of
storage). MDA (malondialdehyde) content (8.2 nmol/g after 8 days of storage) and
PPO (polyphenol oxidase) activity (520.7 U/min mL at the end of storage) were
lower compared to control (Xing et al.
2010
).
1.7.1.2
Carrots
Growth potential of inoculated pathogens such as
Escherichia coli O157
:
H7
, was
tested on carrots stored under PMAP (two OPP fi lms were used with OTR of 3,500
and 1,100 cm
3
m
−2
day
−1
atm.
−1
for OPP 1 and OPP 2 respectively) at 5 and 25 °C
for 8 days.
E. coli O157
:
H7
reached 7, 8 and 8.4 log CFU/g on samples stored in
OPP 1, OPP 2 and control bags, respectively after 3 days of storage at 25 °C. At
5 °C, pathogens strains survived but did not increase their populations (Abadias
et al.
2012
).
Alasalvar et al. (
2005
) focused on shredded orange and purple carrots under
MAP (95 % O
2
/5 % CO
2
, 5 % O
2
/5 % CO
2
) at 5 ± 2 °C. A major decrease in antioxi-
dant activity (from 220 to 180
mol TE/g) under specifi c conditions (95 % O
2
+ 5 %
CO
2
) was reported for purple carrots. A signifi cant reduction of the accumulation of
total phenols resulted in better sensory quality and extended shelf-life for purple
carrots (for at least 2-3 more days).
Amanatidou et al. (
2000
) studied the impact of high O
2
and high CO
2
MA (90 %
O
2
/10 % CO
2
, 80 % O
2
/20 % CO
2
, 50 % O
2
/30 % CO
2
, 70 % O
2
/30 % CO
2
, 1 %
O
2
/10 % CO
2
) in the presence of citric acid (0.1 or 0.5 %), hydrogen peroxide, chlo-
rine, CaCl
2
and an alginate edible coating on the preservation of carrots. The origi-
nal appearance of the carrots for 8 days at 8 °C was maintained by applying citric
acid 0.5 % (w/v). Firmness of carrots and initial pH were not affected by the chlo-
rine treatment. Satisfactory quality was recorded for carrots stored in lesser than
50 % O
2
/30 % CO
2
.
Passive MAP at both temperatures led to a severe decrease in pH of carrots.
Inoculation with microorganisms such as
Listeria
or
Salmonella
infl uences the
product's pH probably because of metabolism by-products. Treatment with chlorine
dioxide induced minor pH changes versus storage (Fig.
1.1
).
Ready-to-eat (RTE) carrots, after being peeled and sliced, were packed (4 °C)
under passive (PP fi lm used) and A MAP at low (5 % O
2
, 10 % CO
2
,) and high
oxygen concentrations (80 % O
2
, 10 % CO
2
) after dipping into citric acid
ʼ
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