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Influence of Modified Atmosphere Packaging on Postharvest Quality of Baby Spinach ( Spinacia oleracea L.) Leaves

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The aim of the current study was to determine the influence of modified atmospheric pressure on the quality of baby spinach during storage. Treatments consisted of control [(normal air) (78% N2; 21% O2)], modified atmosphere (MA) (5% O2; 15% CO2; balance N2), storage temperature (4, 10, and 20 °C), and number of days after storage (0, 3, 6, 9, and 12). Parameters recorded are gas composition, weight loss, sensory quality, minerals and trace elements (Mg, Fe, and Zn), flavonoids, and antioxidant activity. The results of this study demonstrated that in the headspace gas there was overall reduction in O2 and increase in CO2 levels over the storage period. After 6 days of storage, all samples in normal air irrespective of the storage temperature were found to fall short of acceptable marketability with regard to visual appearance. The total antioxidant activity and flavonoids were well maintained under controlled atmosphere (CA) at 4 °C when stored for 9 days. © 2018, American Society for Horticultural Science. All rights reserved.
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HORTSCIENCE 53(2):224–230. 2018. https://doi.org/10.21273/HORTSCI12589-17
Influence of Modified Atmosphere
Packaging on Postharvest
Quality of Baby Spinach (Spinacia
oleracea L.) Leaves
Ambani R. Mudau
Department of Life and Consumer Sciences, University of South Africa,
Private Bag X6, Florida 1710, South Africa
Puffy Soundy
Department of Crop Sciences, Tshwane University of Technology, Private
Bag X680, Pretoria 0001, South Africa
Hintsa T. Araya
ARC-Roodeplaat Vegetable and Ornamental Plant Institute, Private Bag
X293, Pretoria 0001, South Africa
Fhatuwani N. Mudau
1
Department of Agriculture and Animal Health, University of South Africa,
Private Bag X6, Florida 1710, South Africa
Additional index words. leaf vegetable, storage temperature, sensory quality, gas composition,
off odor
Abstract. The aim of the current study was to determine the influence of modified
atmospheric pressure on the quality of baby spinach during storage. Treatments
consisted of control [(normal air) (78% N
2
; 21% O
2
)], modified atmosphere (MA) (5%
O
2
; 15% CO
2
; balance N
2
), storage temperature (4, 10, and 20 8C), and number of days
after storage (0, 3, 6, 9, and 12). Parameters recorded are gas composition, weight loss,
sensory quality, minerals and trace elements (Mg, Fe, and Zn), flavonoids, and
antioxidant activity. The results of this study demonstrated that in the headspace gas
there was overall reduction in O
2
and increase in CO
2
levels over the storage period.
After 6 days of storage, all samples in normal air irrespective of the storage temperature
were found to fall short of acceptable marketability with regard to visual appearance.
The total antioxidant activity and flavonoids were well maintained under controlled
atmosphere (CA) at 4 8C when stored for 9 days.
The biggest problem faced by the food
industry in South Africa is the maintenance
of quality of fresh produce during post-
harvest storage (Munhuweyi et al., 2016).
Attempts to reduce losses and maintain
quality of fresh food, primarily fruits and
vegetables, during postharvest storage has
been a challenge and priority for the food
industry (Velickova et al., 2013). Strategies
to prolong the shelf life of fresh-cut vege-
tables during storage are necessary to pre-
serve their nutritional value and to assure
food safety (Conte et al., 2008; Ninfali and
Bacchiocca, 2004).
Modified atmosphere packaging (MAP) is
the technique of sealing actively respiring pro-
duce, fresh fruit and vegetables, in polymeric
film packages to achieve the modification of
the O
2
and CO
2
levels within the package
atmosphere (Mir and Beaudry, 2004). The
MA packaging technology is said to be
efficient in maintaining shelf life of fresh
produce during storage (Sandhya, 2010).
Church and Parsons (1995) reported that the
combination of oxygen (O
2
), nitrogen (N
2
),
and carbon dioxide (CO
2
) is frequently used
when operating the MAP during storage,
based on its efficiency and specific effect it
has in slowing down the metabolism process
of the produce. The high CO
2
or low O
2
concentrations diminish respiration rate,
thus, reduces the occurrence of aerobic bac-
teria and deterioration rate of the stored
product (Babic and Watada, 1996).
The concentrations of O
2
in MAP during
storage of fresh-cut fruits and vegetables for
both quality and safety should range between
1% and 5% (Sandhya, 2010), whereas CO
2
concentrations should be above 10% (Zagory
and Kader, 1988). Izumi et al. (1997) dem-
onstrated the benefits of low O
2
atmospheres
on spinach during storage. In addition, Gil
et al. (1999) and Ko et al. (1996) reported
reduced respiration rate, weight loss, and
antioxidant loss on spinach stored in low O
2
concentrations. There is limited data avail-
able describing storage requirement of baby
spinach using MAP. Thus, the objective of
this study was to determine the effect of CA
on postharvest quality and shelf life of baby
spinach (Spinacia oleracea L.).
Materials and Methods
Experimental site. The trial was carried
out at the Agricultural Research Council
Vegetable and Ornamental Plant Institute
situated 25 km north of Pretoria on the
KwaMhlanga Road (R573), Gauteng Prov-
ince, South Africa, at lat. 2559#S; long.
2835#E. The study was initiated during
mid-May to early July 2014 and repeated in
June to late Aug. 2015, which was suitable
for baby spinach production in South Africa.
Plant materials. Ohio, a baby spinach
cultivar (Hygrotech, Pretoria, South Africa)
was used for the study. Seedlings of baby
spinach (S. oleracea L.) were thinned after
10 d of days after planting (DAP). Plants
were fertilized with a balanced nutrient solu-
tion that contained all nutrients as described
by Nemadodzi et al. (2017) and Zikalala et al.
(2016). The initial soil chemical analyses
were determined using a procedure described
by Hanlon et al. (1994). The field soil
conditions were light sandy clay soils, with
a pH ranging from 7.3 to 7.7. All plants were
irrigated by using drip irrigation system. The
trial was ended 37 DAP.
Treatment and experimental design.
Treatments consisted of control (78% N
2
;
21% O
2
), MA (5% O
2
; 15% CO
2
; balance
N
2
), at temperatures (4, 10, and 20 C) and
number of days (0, 3, 6, 9 and 12) arranged in
a randomized block design with five repli-
cates. Parameters recorded were gas compo-
sition, weight loss, sensory quality, minerals
and trace elements (Mg, Fe, and Zn), flavo-
noids and antioxidant activity.
Weight loss. Baby spinach leaves were
weighed using a digital electronic balance
[Model MK-500C, DENVER instrument
(±0.001 g); Sigma-Aldrich, St Louis, MO]
at the beginning and end of each storage
period expressed as percentage weight loss.
Gas composition. Headspace O
2
and CO
2
concentrations in packages of baby spinach
were measured using a PBI Dansensor
CO
2
/O
2
gas analyzer (Checkmate 9000,
Ringsted, Denmark) by inserting the needle
of the measuring assembly through a septum
adhered to the packaging container during
every storage interval (Mampholo et al.,
2013). At each sampling interval, five pack-
ages from atmosphere conditions were mea-
sured and thereafter, the mean value was
determined.
Sensory analysis (visual appearance and
off odor). Sensory attributes were scored
based on the methods described by Medina
et al. (2012) with slight modifications. Prod-
uct quality was evaluated in fresh material
and after 3, 6, 9, and 12 d of storage. Overall
acceptance and odor evaluation was carried
Received for publication 10 Oct. 2017. Accepted
for publication 6 Dec. 2017.
This work was financially supported by the Gauteng
Department of Agriculture and Rural Development
(GDARD; GUN number 359000).
1
Corresponding author. E-mail: mudaufn@unisa.
ac.za.
224 HORTSCIENCE VOL. 53(2) FEBRUARY 2018
out by 10 trained panelists between 23 and
45 years of age (70% females and 30% males).
In an assessment of postharvest decay condi-
tion, the samples were individually scored in
hedonic scale arranged as 1 to 9 [where 9 =
excellent, 7 = good (some leaves slightly
yellowed or decayed), 5 = fair (with accept-
able marketability), 3 = poor (dominated by
yellow or decayed leaves), 1 = extremely poor
(inedible)]. With regard to odor, a scale of 1 to
9 was applied: where 9 = excellent, 7 = slightly
off-odor, 5 = moderate off-odor, 3 = strong
off-odor, and 1 = intolerable off-odor.
Leaf color. Surface color of spinach
leaves was objectively measured using a Min-
olta CR-400 chromameter (Minolta, Osaka,
Japan), calibrated with a white tile. Five
leaves per atmosphere condition were mea-
sured at 0, 3, 6, 9, and 12 d of storage. The
change in total color that occurred during
the storage (DE) was determined using the
formula:
DE=DL
ðÞ
2+Da
ðÞ
2+Db
ðÞ
2
hi
1
=
2
where DL*, Da*, and Db* are differences in
spinach color between day 0 and the sam-
pling day (Pandrangi and LaBorde, 2004).
Mineral and trace elements. All mineral
and trace elements were analyzed using
a method described by van der Walt et al.
(2009).
Table 1. Percentage cumulative weight loss of packaged baby spinach stored under modified atmosphere
packaging (5% O
2
; 15% CO
2
; balance N
2
) and under untreated atmosphere (78% N
2
; 21% O
2
) at 4, 10,
and 20 C for 12 d.
Storage duration (d)
Wt loss (%)
z
Modified atmosphere packaging Untreated atmosphere
4C10C20C4C10C20C
0 0.00 b 0.00 d 0.00 c 0.00 bc 0.00 c 0.00 d
3 0.39 a 1.59 c 3.39 b 0.06 c 3.14 b 4.21 c
6 0.55 a 2.93 b 3.60 b 0.61 b 3.33 b 6.23 b
9 0.89 a 3.08 b 5.33 a 1.19 a 5.23 a 6.76 b
12 0.94 a 5.03 a 5.79 a 2.24 a 5.29 a 7.56 a
z
Weight loss (%) is presented as the mean of five replicates. Means in columns with different letters are
significantly different (P#0.05) using Duncan’s multiple range test.
Fig. 1. Changes in headspace gas composition [% O
2
(A) and % CO
2
(B)] of baby spinach stored at 4, 10,
and 20 C for 12 d in modified atmosphere (5% O
2
; 15% CO
2
; balance N
2
) and untreated atmosphere
(78% N
2
; 21% O
2
). Each value represents the mean of five determinations at each temperature ±SE.
Data points indicate mean gas composition SE.
Fig. 2. Influence of modified atmosphere and normal air conditions on overall appearance in baby spinach leaves stored at 4, 10, and 20 C for 12 d. Data points
indicate mean score SE.
HORTSCIENCE VOL. 53(2) FEBRUARY 2018 225
Determination of antioxidant activity.
Antioxidant activity (by free radical scav-
enging) of the extracts was determined using
Trolox equivalent antioxidant capacity assay
as described by Awika and Rooney (2004).
Evaluation of total flavonoid content. The
total flavonoids were measured using a mod-
ified calorimetric method described by Yoo
et al. (2008) and slightly modified by Mudau
et al. (2015).
Statistical analysis. Data were subjected
to analysis of variance using IBM SPSS
statistics version 23.0. Means were separated
using Duncan’s multiple range test. The
Wilcoxon Mann–Whitney test was used for
sensory analysis to compare treatments ap-
plied during postharvest. The significant
differences were considered at P< 0.05.
Results
Weight loss (MAP). Table 1 showed that
baby spinach leaves stored under MA from 3
to 12 d significantly reduce % weight loss.
The difference between the highest and
lowest weight loss was 0.94% when stored
at 4 C, whereas at 10 and 20 C, the highest
weight loss was 5.03% and 5.79%. All
treatments significantly maintained percent-
age weight loss with the highest achieved at
12 d of storage.
Untreated (normal) atmosphere. Percent-
age weight loss (%) in spinach leaves stored
under normal air showed demonstrated sim-
ilar trends in all storage temperature for 12 d
(Table 1). After 12 d, the highest weight loss
(7.56%) was observed in samples stored at
20 C. The least weight loss (2.24%) was
observed in the samples stored at 4 C. This
storage temperature showed great potential in
maintaining weight than at 10 and 20 C.
However, the CA samples maintained more
weight greater than those that were exposed
to untreated atmosphere.
Gas composition. Figure 1A and B dem-
onstrated the changes in the headspace gas
composition of baby spinach in MA and
normal air conditions at different tempera-
tures over the storage period. There was
a rapid decrease of O
2
ranging from 4.9%
to 2.5% on the 3 d of storage at 20 C. A faster
CO
2
production was observed at 20 C on the
3 d of storage under baby spinach leaves
stored at normal air condition, ranging from
15.5% to 19.2%. Irrespective of gas condi-
tions, samples stored at 20 C had the lowest
O
2
and the highest CO
2
followed by those
stored at 10 and 4 C.
Sensory analysis. Significant differences
(P< 0.05) in the overall visual appearance
and off-odor were observed among baby
spinach samples stored in MA and normal
air condition at different temperatures over
the storage duration (Figs. 2 and 3). Samples
from all treatments scored high with similar
values for day 0 and no significant difference
was noted (P> 0.05), whereas on the day 3,
samples stored in normal air at 20 C showed
signs of a faster deterioration in quality from
all other treatments (Fig. 2). Samples in MA
at 10 C had better quality than those in
normal air condition stored at 4 C on the 6
and 9 d of storage. In comparison between
samples in MA and normal air conditions,
significantly faster quality deterioration was
observed in samples exposed to normal air.
This was evident in that after 6 d of storage;
all samples in normal air irrespective of the
storage temperature were found to fall short
of acceptable marketability. On the 12 d,
samples in CA stored at 4 C still had overall
quality for acceptable marketability.
Moderate off-odor was observed after
12 d of storage in spinach samples under
MA when stored at 4 C (Fig. 3). However,
samples exposed to normal air stored at
similar temperature after 12 d had strong
off-odor. Furthermore, no significant differ-
ences (P> 0.05) were observed among
samples under MA and normal air at 4 C
during the entire storage period. Similar trend
was observed in samples stored at the storage
temperature of 10 and 20 C for modified and
normal air conditions, respectively. Samples
exposed to normal air at 20 C revealed
a defect which occurred rapidly because
a strong off odor was evident on day 6 of
storage.
Leaf color. Statistical analysis of color
changes in spinach leaves during storage
showed slight differences in MA at all three
storage temperatures. In general, the nature
of samples stored under normal air showed
significantly lower a*, higher b*, and higher
chroma than samples stored in MA. The color
differences (DE) increased (P< 0.05) in both
MA and normal air samples and most rapid
changes were observed at 20 C (Fig. 4).
Whereas, samples stored at 4 and 10 C
Fig. 3. Influence of modified atmosphere and normal air conditions on the off-odor in baby spinach leaves
stored at 4, 10, and 20 C for 12 d.
Fig. 4. Change in total color (DE) of spinach packaged with modified atmosphere (5% O
2
; 15% CO
2
;
balance N
2
) and control (78% N
2
; 21% O
2
) at 4, 10, and 20 C for 12 d. Each value represents the mean
of five determinations at each temperature ±SE. Data points indicate color change SE.
226 HORTSCIENCE VOL. 53(2) FEBRUARY 2018
remained constant during the entire storage
duration.
Mineral and trace elements. Modified
atmospheric pressure revealed a similar ef-
fect of normal air on Mg, Fe, and Zn.
Magnesium concentration was highly
retained in the lowest storage temperature
regardless of the surrounding gas composi-
tion on the spinach leaves (Fig. 5A). After
12 d of storage, spinach leaves stored at 4 C
under MA and normal air conditions had Mg
concentration of 11 and 9.2 mg·kg
–1
dry
weight (DW). The least concentration of
Mg was pronounced in spinach leaves stored
at 20 C under MA (7.5 mg·kg
–1
DW) and
normal air (7 mg·kg
–1
DW). The rate in which
Fe was declining was very slow compared
with Mg and Zn concentration. Iron concen-
tration ranged between 0.4 and 0.67 mg·kg
–1
DW in both gas conditions (Fig. 5B). Iron
concentration was not significantly different
(P> 0.05) between MA and normal air
conditions. From 3 to 9 d of storage, Zn
concentrations were similar at 4 and 10 C
(Fig. 5C).
Total antioxidant activity. Total antioxi-
dant activity decreased in all treatments;
however, the baby spinach stored under MA
showed better activity when compared with
those stored in a normal air. During storage
period at 4 C, total antioxidant activities
were closer in both MA and normal air
conditions. Nevertheless, at the end of the
experiment baby spinach leaves stored under
MA demonstrated a higher maintenance of
total antioxidant activity when compared
with those stored in the normal air environ-
ment (Fig. 6).
On the other hand, it was found that the
total antioxidant activity in baby spinach
leaves stored under normal atmosphere dras-
tically decreased, after day 3 in particular,
from 6.45 to 5.58 mg·kg
–1
DW, whereas
those stored under MA slightly decreased
from 6.45 to 5.91 mg·kg
–1
DW (Fig. 7). Thus,
Fig. 5. Effect of modified atmosphere on the Mg (A), Fe (B), and Zn (C) in the spinach leaves stored at 4, 10, and 20 C for 12 d. Data points indicate mean SE.
Fig. 6. Total antioxidant activity (mg·kg
–1
DW) of baby spinach leaves stored under modified atmosphere
(5% O
2
; 15% CO
2
; balance N
2
) and control (78% N
2
; 21% O
2
), at 4 C for 12 d. Data points indicate
mean total antioxidant activity SE.
HORTSCIENCE VOL. 53(2) FEBRUARY 2018 227
the total antioxidant activity was significantly
affected as the difference was statistically
significant. It can be concluded that the MA
technique is ideal as it delays degradation of
leaf pigment. Immediately, after day 3 of
storage period, it was clear that the highest
level of total antioxidant activity was ob-
served in the baby spinach leaves stored at
4C under MA when compared with the
other samples stored at 10 and 20 C under
both MA and normal air atmosphere (Figs.
5–7).
In fact, the total antioxidant activity in the
baby spinach leaves stored under MA at 4 C
after 3 and 12 d of storage period was 6.39
and 4.41 mg·kg
–1
DW, respectively, as shown
in Fig. 8. Whereas, the lowest total antioxi-
dant activity after 3 d (3.65 mg·kg
–1
DW) and
12 d (2 mg·kg
–1
DW) was observed at 20 C
in baby spinach leaves stored under untreated
atmosphere. Although the baby spinach
leaves stored under normal atmosphere had
shown very poor total antioxidant sustain-
ability, baby spinach leaves stored at 4 C
resembled the steadiest of total antioxidant
over those stored at 10 and 20 C under
normal air.
Total flavonoid content. Total flavonoids
in samples stored in MA ranged from 6.12 to
25.14 mg·kg
–1
DW, whereas total flavonoids
of untreated (normal) samples ranged from 5
to 25.14 mg·kg
–1
DW in all three different
temperatures (Figs. 9–11). Total flavonoid
contents decreased as the storage duration
increased in all treatments. However, baby
spinach samples under MA when stored at
4C showed higher capacity to retain the
high levels of total flavonoids from the
beginning of storage until day 12 (Fig. 9).
There was a significant difference between
modified samples stored at 4 and 20 C after
day 6 of storage.
Discussion
The headspace gas composition com-
pletely relies on the fresh produce O
2
con-
sumption and CO
2
production rate when
packaged and stored (Mastromatteo et al.,
2012). The increase in O
2
consumption and
CO
2
production with relative increase in
temperature over storage time could be at-
tributed to the respiration activity of baby
spinach. Samples in CA had slow O
2
con-
sumption and CO
2
production rate compared
with those stored in normal air condition.
Thus, the findings in this study suggest that
CA coupled by low temperature over storage
period could reduce respiration rate, which
leads to extended shelf life of the fresh
produce. Similar findings were obtained in
previous studies for baby spinach (Kaur et al.,
2011; Kou et al., 2014; Tudela et al., 2013).
Furthermore, similar results were found by
other authors for different vegetables (Leceta
et al., 2015).
Weight loss during storage period varies
depending on the vegetable, packaging con-
ditions (include modified atmospheric pres-
sure), and also, temperature levels. Modified
atmosphere has proved to reduce weight loss
compared with normal air. Similar findings
were confirmed in the study conducted by
Antmann et al. (2008), who observed a weight
loss of 72% after 6 d of storage at 5 Cin
unpackaged mushrooms, whereas mushroom
in packaged conditions reduced weight loss.
Reduced weight loss in plants stored under
MA could be caused by the fact that the
respiration rate is passive, and also carbohy-
drate resources were consumed slowly in the
atmospheric condition. In this current study,
weight loss increased with storage duration
gradually. However, at higher temperature it
has been observed that there is a rapid in-
crease. This could be attributed to the fact
that high temperature may increase the res-
piration rate which may result in dehydrated
product. Mudau et al. (2015) and Watada
et al. (1987) reported similar findings as
greater loss of weight was observed in baby
spinach samples stored at 20 C. Zenoozian
(2011) reported the maximum weight loss of
spinach during storage at 10 and 25 C when
stored in normal air; however, active MA
packaging had minimum loss of weight.
Spinach samples under MA were consid-
ered not acceptable for marketing after 9 and
12 d at 20 and 10 C, respectively. Similar
findings were reported by Pandrangi and
LaBorde (2004), who found that spinach
under normal air stored at 4, 10, and 20 C
were commercially unacceptable after 8, 6,
and 4 d, respectively. Although less pro-
nounced in their studies, we assume that the
extended of commercial acceptability in our
findings was effected by an introduction of
modified atmospheric pressure.
The shelf life of the stored produce is
pronounced to be influenced largely by sen-
sory quality parameters, among others, odor,
which may either invigorate or discourage
consumers’ consumption. Off-odor became
notably more perceptible in spinach leaves
Fig. 7. Total antioxidant activity (mg·kg
–1
DW) of baby spinach leaves stored under modified atmosphere
(5% O
2
; 15% CO
2
; balance N
2
) and control (78% N
2
; 21% O
2
), at 10 C for 12 d. Data points indicate
mean total antioxidant activity SE.
Fig. 8. Total antioxidant activity (mg·kg
–1
DW) of baby spinach leaves stored under modified atmosphere
(5% O
2
; 15% CO
2
; balance N
2
) and control (78% N
2
; 21% O
2
), at 20 C for 12 d. Data points indicate
mean total antioxidant activity SE.
228 HORTSCIENCE VOL. 53(2) FEBRUARY 2018
exposed to normal air stored at 10 and 20 C
as the storage duration increased. When
considering O
2
evolution, oxygen uptake will
rise with an increase in storage temperature.
Most importantly, low O
2
and high CO
2
concentrations retarded the respiration rate.
Off-odor was less pronounced in MA sam-
ples stored at 4 and 10 C, whereas similar
trend was observed with those samples ex-
posed to normal air at 4 C. It was only MA
samples stored at 4 C which were found to
be commercially acceptable after 12 d of
storage. These findings were in agreement
with results found by Tudela et al. (2013),
who reported that baby spinach exposed to
low O
2
with CO
2
was rejected after 10 d at
7C.
According to Rizzo and Muratore (2009),
color remains to be the core parameter that
customers apply when judging the quality of
vegetables. Our findings were similar to those
reported by Pandrangi and LaBorde (2004).
In their study, they found that there was no
significant difference after 8, 6, and 4 d at 4,
10, and 20 C. Rizzo and Muratore (2009)
reported that unacceptable color change from
green to yellow was more noticeable in con-
trols, whereas MAs of celery leaves showed no
signs of color change.
The postharvest storage retained high
level of antioxidant under low temperature.
This findings concur with the study by Mudau
et al. (2017), who reported that the antioxi-
dant content were mostly retained at 4 C
when compared with 10 and 22 C. This
could be attributed to metabolic reactions that
are greatly reduced, although are not shut
down completely. Pereira et al. (2014)
experimented the effect of CA on the total
antioxidant activity in the radicchio (Cicho-
rium intybus L.) when stored at 1 C for 10 d
and observed that there was a slight increase
in the total antioxidant activity for first 3 d of
storage, and thereafter declined drastically.
Chu et al. (2002) stressed that there is no clear
indication on the causes of antioxidant activ-
ity variation in the vegetables during storage.
However, it is commonly understood that the
antioxidant activity of vegetables totally de-
pends on several compounds, such as flavo-
noids, phenolic acids, amino acids, and ascorbic
acid.
Total flavonoids were well maintained at
4 and 10 C, whereas there was a drastic
decline at 20 C. Gil et al. (1999) reported an
increase of total flavonoids in Swiss chard
during storage at 6 C under CA, whereas this
increase was not significant in the air-stored
Swiss chard. The present study findings
concurred with the study by Gil et al.
(1999) in that there was no significant differ-
ence between the total flavonoids in plants
stored in CA and those stored in normal air,
except at high storage temperature. Else-
where, Martínez-S
anchez et al. (2006) re-
ported that the flavonoids content in the wild
rocket leaves remained constant or even in-
creased during storage when stored in CAs at
temperature of 1.5 to 4 C for 14 d, whereas
flavonoids in leaves stored under normal air
kept on declining even when stored at low
Fig. 9. Total flavonoid contents (mg·kg
–1
DW) in baby spinach leaves stored under modified atmosphere
(5% O
2
; 15% CO
2
; balance N
2
) and control atmosphere (78% N
2
; 21% O
2
), stored at 4 C for 12 d. Data
points indicate mean total antioxidant activity SE.
Fig. 10. Total flavonoid contents (mg·kg
–1
DW) in spinach leaves stored under modified atmosphere (5%
O
2
; 15% CO
2
; balance N
2
) and control atmosphere (78% N
2
; 21% O
2
), stored at 10 C for 12 d. Data
points indicate mean total flavonoids SE.
Fig. 11. Total flavonoid contents (mg·kg
–1
DW) in spinach leaves stored under modified atmosphere (5%
O
2
; 15% CO
2
; balance N
2
) and control atmosphere (78% N
2
; 21% O
2
), stored at 20 C for 12 d. Data
points indicate mean total flavonoids SE.
HORTSCIENCE VOL. 53(2) FEBRUARY 2018 229
temperature. This could indicate that MAP
can have pronounced effects of metabolism
of phenolics depending on the variety or
cultivar. Modified atmosphere packaging
also plays a crucial role in reducing the
oxygen level around the produce during
storage, which inhibits the existence of aer-
obic microorganisms.
When considering all conditions under
which this study was carried out, it has been
found that baby spinach leaves stored under
CA (5% O
2
; 15% CO
2
; balance N
2
)at4C
for 9 d maintained a high level of antioxidant
activity and flavonoids. Common observa-
tion was that substantial losses of nutrients
occurred at each storage temperature. Thus, it
is ideal to apply a combination of control
atmosphere and low temperature to promote
longer shelf life without compromising the
produce quality during storage.
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230 HORTSCIENCE VOL. 53(2) FEBRUARY 2018
... Visual Quality (VQ) was scored according to the methods of Medina et al. (2012) and Mudau et al. (2018) with partial modifications. VQ was evaluated by six trained panel members with equal gender ratio, ages ranging between 25-40 years old, considering appearance, color, brightness, uniformity, and freshness following a 9-point Hedonic scale where, 9= ""Excellent""; 1= ""Extremely poor""; 5= ""Fair"". ...
... In a report conducted by Garande et al. (2019), WL was determined as 8.54 and 9.64% in PE bags at 5 °C on the 6 th and 8 th days of the storage. Meanwhile, the results of WL were lower than the findings of Mudau et al. (2018), who stored spinach in MAP at 4 and 10°C for 12 days and 7 days, respectively. Spinach quality is particularly sensitive to WL, with 3% water loss, making this commodity unmarketable (Bartz and Brecht, 2002). ...
... According to the experience, this could be greatly dependent on multiple factors such as variety, growth stage, storage period, and temperature. Mudau et al. (2018) pointed out that a score of 5.0 for VQ could be a marker for the end of shelf life or marketability period in spinach. Based on these visual scores after 15 days of storage, spinach was considered commercially unacceptable after 6 days at 4 °C and 3 days at 10 °C, respectively, in MAPs in terms of showing yellowing, and decay. ...
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... Although MAP is not a substitute for proper temperature management (Lange, 2000), it may have the potential to benefit stored spinach when the cooling capabilities are limited and could be a prospective solution for reducing postharvest spinach losses for those growers who lack proper cooling and storage facilities. A beneficial effect of MAP for produce that is stored in nonoptimum temperatures has been reported for a variety of crops (D'Aquino et al., 2016;Fonseca et al., 2005;Løkke et al., 2012;Murmu and Mishra, 2017), including spinach (Garrido et al., 2016;Medina et al., 2012;Mudau et al., 2018). The main challenge for applying passive MAP in nonoptimum storage temperatures is finding a film with appropriate OTR that can match the respiration rate of the stored product (Lange, 2000) and create a beneficial atmosphere for the product. ...
... However, maintaining the optimum storage temperature is not always feasible, especially in smaller horticultural operations (Cantor and Strochlic, 2009;Harrison et al., 2013). The optimum postharvest temperature for leafy greens is near 0°C, but there have been MAP designs that have shown benefits at nonoptimum storage temperatures (Fonseca, 2006;Løkke et al., 2012;Mudau et al., 2018). Table 1. ...
... acephala DC.) was extended for 2 d when stored in MAP vs. air at 20°C to simulate retail handling conditions (Fonseca et al., 2005). Wild rocket (Diplotaxis tenuifolia L.) maintained good visual quality after 4 d of MAP storage at 10°C (Løkke et al., 2012), whereas the shelf life of spinach stored in MAP at 20°C was extended for 3 d (Mudau et al., 2018). Our results indicate that passive MAP created using the Breathe-Way technology is beneficial to the postharvest quality and storage life of spinach at nonoptimum storage temperatures. ...
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... Even for the same crop, depending on whether Lactuca indica L. is a whole or baby leaf variety and whether tomatoes are whole or fresh cut, the loss rate of fresh weight during storage, the changes in the overall quality, and the O2, CO2, and ethylene concentrations in the films during film packaging showed differences in storability [12,13]. It was reported that when baby spinach leaves were packaged in a modified atmosphere at a ratio of 5% O2 to 15% CO2, high levels of antioxidant activity were maintained, and the shelf life was extended compared to the untreated atmosphere [14]. The modified atmosphere packaging of rocket leaves has a beneficial effect on the quality; this packaging method can cause off-odor, but it retains its typical flavor for up to 6 days [15]. ...
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This study aimed to examine the effect of modified atmosphere (MA) storage on the quality and storability of romaine lettuce. Whole and fresh-cut romaine lettuce were packaged with 1300; 10,000; 50,000; 100,000 cc m−2·day−1·atm−1 O2 transmission rate (OTR) films and stored at 2 or 8 °C for 15 days. The respiration and ethylene production rates before pre-cooling were higher in fresh-cut lettuce than in whole romaine lettuce. The reduction in fresh weight for whole and fresh-cut romaine lettuce during storage was less than 0.5%. The CO2 concentration was less than 2%, except for the 1300 cc treatment (at 8 °C for whole and fresh-cut lettuce) and 10,000 cc (in fresh-cut lettuce). At the end date of storage, the overall quality of the whole lettuce was good, the off-odor was lower in the 10,000 cc treatment, and the 50,000 cc treatment at 8 °C led to good overall quality in the fresh-cut lettuce. The chlorophyll content of the whole lettuce was maintained at a higher level in the treatment of 10,000 cc at 8 °C, while it was higher in the 50,000 cc treatments at 2 and 8 °C in the fresh-cut lettuce. Correlation and PCA confirmed that the main factors affecting the storability and quality of romaine lettuce were fresh weight loss rate, off-odor, and the concentration of CO2. In addition, the storage characteristics of whole and fresh-cut lettuce were opposite to 0 in PC1 and PC2, indicating that the storage characteristics were different depending on the processing type.
... Atmospheric packaging is an elegant way of preserving vegetables by controlling the composition of gas in the storage environment, thus reducing the rate of vegetable respiration and metabolism, inhibiting the growth and reproduction of spoilage bacteria and extending the storage period of vegetables [4]. Mudau et al. [5] found that the total antioxidant activity and the flavonoid content of fresh-cut spinach were well maintained at 4 • C in an aerated package (5% O 2 , 15% CO 2 , 80% N 2 ). Francisco et al. [6] indicated that a high O 2 atmosphere inhibited microbial growth and effectively suppressed the browning of fresh-cut lettuce. ...
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Fresh-cut vegetables are prone to microbiological contamination and oxygenation during handling and storage. In this study, fresh-cut amaranth was subjected to various gas ratios (5–15% O2, 5–15% CO2, 80% N2) for 12 days. Chlorophyll content, ascorbic acid content, antioxidant enzyme activity, microbial population, and physiological and biochemical indicators were measured to evaluate the impact of atmospheric packaging. Suitable atmospheric packaging could slow the respiration of amaranth, delay the decline in physiological and biochemical characteristics, maintain the antioxidant enzyme activity, promote the sensorics, and prolong the shelf life by 2 days. According to the analysis of the results, modified atmospheric packaging (10% O2, 10% CO2, 80% N2) retarded the decline in fresh-cut amaranth quality, provided effective antioxidative browning, and inhibited Pseudomonas fluorescens development.
... for strawberry was similar to that reported for packaged whole strawberry fruit (%0.09% per day) held at 1 C (Nunes et al., 1998). Mudau et al. (2018) found about 0.18% weight loss per day for spinach in perforated low-density polyethylene packages held at 4 C. For carrots, a weight loss rate of 0.14% per day was recorded for roots stored in microperforated packages at 4 C (Mastromatteo et al., 2012). ...
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... Oxidative damage might be possibly reduced with the conservation of higher antioxidant activities during storage . Earlier, it has been reported that MAP coupled with low temperature storage significantly displayed higher antioxidants in spinach during storage by altering atmospheric gases inside (Mudau et al., 2018). Similar results for conserving antioxidants have been reported for litchi (Ali et al., 2019a), pomegranate arils (Mphahlele et al., 2016) and sweet cherries (Wang et al., 2015) during storage. ...
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Temperature abuse of fresh-cut products occurs routinely during transport and retail store display. However, the stage of product shelf life during temperature abuse and its impact on sensory attributes have not been studied. This study evaluated the effect of temperature abuse occurring immediately after processing and late in shelf life through measurements of sensory attributes, and membrane integrity of commercially packaged ready-to-eat baby spinach. The packaged products were received within 2 days of processing. Samples subject to early temperature abuse were immediately placed at 1, 4, 8, 12, 16 and 20 C storage upon arrival, and those subject to late temperature abuse were stored at 1 degrees C for six days, and then transferred to 4, 8, 12, 16 and 20 degrees C storage. Package headspace gas composition, in-package visual appeal, purchase intent, product color, off-odor, decay, texture, overall quality, and tissue electrolyte leakage were evaluated every 1-2 day up to 16 day total. Results indicate that when the product temperature is maintained at 1-4 degrees C, the quality of commercially packaged baby spinach can be retained for up to 18 days post-processing. However, storage temperature of 8 C or above, significantly (P<0.001) shortened product shelf life as exhibited by accelerated tissue electrolyte leakage, product yellowing, decay and off-odor development. Most importantly, the product's shelf life stage significantly affected its response to temperature. Quality deterioration proceeded more rapidly when temperature abuse occurred in late as opposed to early shelf life stage. Published by Elsevier B.V.
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