Application of Modified Atmosphere Packaging on Quality of Selected Vegetables: A Review - Application of Modified Atmosphere Packaging on Quality of Selected Vegetables - page 20

presence of stains on the leaf surface or browning on the midribs than those in
AMAP, thus indicating a higher rate of deterioration.
Combined ultraviolet-C radiation (0.4, 0.81, 2.44, 4.07, and 8.14 kJ/m 2 ) and pas-
sive MAP (BOPP fi lm used) were applied by Allende and Artes ( 2003a ) to diminish
the growth of psychrotrophic (0.5-2 log CFU/g reduction) and coliform bacteria as
well as yeast growth. The sensory quality of lettuce pieces was not adversely
affected by this combined treatment when compared to control samples.
Aerobic counts with microbial limit of 7 log CFU/g were established by the
Spanish legislation exceeded on day 5 for control, and by day 8 for product treated
with 4.06 or 8.14 kJ/m 2 thereby showing that UV-C treatment and storage at 5 °C
under MAP (bioriented polypropylene fi lm (BOPP) used) conditions prolonged
shelf life of ' Lollo Rosso ' lettuce. Enhanced tissue brightness was due to the highest
dose whereas browning was reduced when 2.44, 4.07, and 8.14 kJ/m 2 were applied
(Allende and Artes 2003b ).
Iceberg lettuce was examined in regard with the impact of packaging atmosphere
(PMAP with OPP fi lm used with or without N 2 fl ushing) and storage temperature (3
and 8 °C) on total ascorbic acid (TAA) by Barry-Ryan and O'Beirne ( 1999 ). TAA
retention (14 and 12 mg/100 g for nitrogen fl ushed and OPP bags, respectively) over
that in unsealed bags (11 mg/100 g) increased by sealing the OPP bags (passive
MAP or nitrogen fl ush) and allowing a MA to develop.
AMAP (4 kPa O 2 and 12 kPa CO 2 ), as described by Beltran et al. ( 2005a ), was
effective in controlling microbial growth in iceberg lettuce, thereby reaching 2.0 log
reduction in relation to samples stored in air. AMAP initiated a 2.0-3.5 log reduc-
tion of coliforms on sanitized samples [washing at 4 °C using three ozonated water
dips (10, 20, and 10 mg L −1 activated with ultraviolet-C light minimum total ozone
dose)], compared with water-washed samples. Shredded lettuce had an excellent
visual quality after washing for all treatments, and no browning was observed.
Two types of atmosphere modifi cation (PMAP with PE bags used and A MAP
(AMAP) with the same bags and initial atmosphere 10 % O 2 -10 % CO 2 ) and initial
wash with chlorinated water was tested on romaine lettuce stored at 8 and 20 °C. The
treatment with chlorinated water reduced initial mesophile counts by 1.5 log CFU/g.
Bidawid et al. ( 2001 ) investigated the effect of various modifi ed atmospheres
(CO 2 , N 2 at 30:70, 50:50, 70:30 and 100 % CO 2 ) on the survival rate of hepatitis A
virus ( HAV ) on romaine lettuce stored at 4 °C and at room temperature. Lettuce
stored under a MA of 70 % CO 2 was found to have the highest HAV survival rates
(83.6 %). The virus survival rates diminished signifi cantly with an increase at stor-
age temperature. The higher CO 2 level caused injury and resulted in enhanced
browning, particularly under 100 % CO 2 .
Chua et al ( 2008 ) undertook the effort to evaluate the importance of temperature
abuse over the storage period. Several enterohemorrhagic E. coli strains, in spite of
their dysfunctional rpoS locus, were able to profi t from applied MAP conditions and
metabolites presence from lettuce surfaces to induce acid resistance at growth per-
missive temperatures ( ≥ 15 °C). However, for MAP-stored lettuce at tempera-

tures ≤ 10 °C or for lettuce under aerobic conditions, no acid resistance was induced.