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Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach

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Abstract

The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color differences (AE), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not significantly (P > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or temperature. Substantial losses of nutrients occurred at each storage temperature. Only 53% of folate in packaged spinach was retained after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Carotenoid losses increased with temperature with only 54%, 61%, and 44%, respectively, of initial detected levels remaining. Vitamin and quality changes were unaffected by presence or absence of packaging.
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C: Food Chemistry & Toxicology
JFS C: Food Chemistry and Toxicology
Retention of Folate, Carotenoids, and
Other Quality Characteristics in
Commercially Packaged Fresh Spinach
S. PANDRANGI AND L.F. LABORDE
ABSTRACT: The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and
other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color
and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color
differences (
E), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage
temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not
significantly (P > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or
temperature. Substantial losses of nutrients occurred at each storage temperature. Only 53% of folate in pack-
aged spinach was retained after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Carotenoid losses
increased with temperature with only 54%, 61%, and 44%, respectively, of initial detected levels remaining.
Vitamin and quality changes were unaffected by presence or absence of packaging.
Keywords: carotenoids, folate, temperature, spinach
MS 20030474 Submitted 8/20/03, Revised 9/17/03, Accepted 8/10/04. Au-
thor Pandrangi is with Dept. of Food Science and Technology, Ohio State
Univ., Columbus, Ohio. Author LaBorde is with Dept. of Food Science, Penn-
sylvania State Univ., Univ. Park, PA 16802. Direct inquiries to author
LaBorde (E-mail: lfl5@psu.edu).
Introduction
Among fresh leafy greens, spinach is an important source of nu-
trients in the diet ranking 2nd behind kale in total carotenoids
and folate (Holden and others 1999; USDA 2003) and 3rd in total
antioxidant capacity behind only garlic and kale (Cao and others
1996). A single 30-g serving of fresh spinach containing 58 g of
folate and 2015 IU of vitamin A is equivalent to 29% and 20% of the
daily value for each respective vitamin (NAS 1989).
Adequate intake of folate is an important factor in the prevention
of neural tube defects such as spina bifida and anencephaly, cor-
onary artery disease, and colorectal cancer (Herbert 1999). Caro-
tenoids in the diet are essential for normal growth, reproduction
and resistance to infection, and deficiencies have been linked to
blindness and increased risk of several types of cancers (Tee 1992).
Previous studies have demonstrated that the nutrient content
of fresh vegetables decreases during storage (Rodriquez-Amaya
1993; Buescher and others 1999). However, there are few studies on
folate degradation in fresh produce during storage. Chen and oth-
ers (1983) reported that folate in fresh spinach decreased by 26%
and 27% after holding for 7 d at 4 °C or 10 h at 20 °C. Gami and Chen
(1985) held Swiss chard at several temperatures and reported
folate decreases of 12% after 10 d at 4 °C and 43% after 6 h at 4 °C.
However, Mullin and others (1982) reported that folate levels in
fresh spinach remained unchanged after storing at 4 °C for 14 d.
Ezell and Wilcox (1962) reported minimal losses of beta-carotene
in kale and collard at 0 °C. However, losses increased to up to 67%
after 4 d of storage at 21 °C. Little or no decreases in carotenoids
have been reported in refrigerated broccoli and green beans
(Wu and others 1992; Paradis and others 1996). However, Barth and
Zhuang (1996) reported that total carotenoids in broccoli decreased
by 42% to 57% after 6 d at 5 °C, and Howard and others (1999) re-
ported a 64% decrease in broccoli after 21 d at 4 °C. In fresh spin-
ach, Simonetti and others (1991) reported a 10% decrease in beta-
carotene after 21 d at 4 to 6 °C. Kopas-Lane and Warthesen (1995)
reported beta-carotene losses of up to 18% after 8 d at 4 °C although
no changes were reported for the xanthophylls neoxanthin, violax-
anthin, and lutein.
Harvested spinach leaves are transported over long distances in
refrigerated trucks to the processing facility where they are sorted,
washed, centrifuged to remove surface moisture, and packaged in
plastic bags. Because of their high respiration rate, packages are
usually ventilated to maintain aerobic conditions inside the bag.
The shelf life of spinach is less than 14 d after harvest (Kader
2002). However, quality decline may be accelerated by structural
degradation, membrane lipid loss, increased respiration, and eth-
ylene production and is sometimes accompanied by increased en-
zymatic activity. Strategies to increase shelf life include reducing
physical damage during processing and storing at lower tempera-
tures in modified atmospheres (Price and Floros 1993). In this study,
the effects of storage temperature and time on retention of folate,
carotenoids, and other quality attributes in commercially pack-
aged fresh spinach were determined.
Materials and Methods
Sample preparation and treatments
Spinach (Spinacia oleracea L., var. Unipack 151) was obtained
from a fresh-cut processor where it had been sorted, washed, and
packed into polyethylene plastic bags (284-g capacity). Each bag
contained approximately 2.5 perforations (1-mm dia) per cm2 of
package surface. After heat-sealing, the bags were immediately
placed in refrigerated rooms until shipped. Bags of spinach were
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Folate and carotenoids in fresh spinach…
transported in insulated boxes to the Pennsylvania State Univ.
Dept. of Food Science within 12 h of packaging.
Spinach in the sealed bags and spinach leaves removed from
bags were placed in temperature-controlled stainless-steel cham-
bers (Lunaire Limited, Williamsport, Pa., U.S.A.) for storage at 4 °C,
10 °C, or 20 °C. The temperature was continuously monitored using
a digital temperature logger (Model HH2002AL, Omega Engineer-
ing Inc, Stamford, Conn., U.S.A.). Relative humidity inside the
chamber was monitored using a Digital Humidity/Temperature
Meter (FisherbrandTM, Fisher Scientific, Pittsburgh, Pa., U.S.A.).
Experiments were performed in duplicate, and for each experiment,
2 random samples were removed for each assayed parameter. 20 °C
samples removed for analysis at 1-d intervals and 4 °C and 10 °C
samples at 2-d intervals. All absolute values are expressed on a wet
weight basis to facilitate comparison to literature, whereas compar-
isons over time were made on dry weight basis because of signifi-
cant weight loss observed during storage.
Color
Surface color of spinach leaves was measured using a spectro-
photometer (Model CM 3500d Minolta Corp., Ramsey, N.J., U.S.A.)
calibrated with a green standard tile (L* = 63.6, a* = –30.09,
b* = 8.92) as recommended by Shewfelt and others (1984). Dupli-
cate samples of 6 to 7 randomly selected leaves were placed above
the instrument so that the 30-mm aperture was completely cov-
ered. The change in total color that occurred during storage (E)
was calculated using the formula:
E = [(L*)2 + (a*)2 + (b*)2]1/2
where L*, a*, and b* are differences in spinach color between
day 0 and the sampling day (Shewfelt and others 1984).
Weight loss
At each sampling interval, spinach bags and spinach leaves were
removed from the chamber and weighed using a top loading bal-
ance (Mettler PM 4600, Mettler-Toledo, Columbus, Ohio, U.S.A.).
Average weight loss per sample was expressed as a percentage of
initial fresh weight.
Microbial populations
Mesophilic and psychrotrophic bacterial populations were de-
termined using the method of Garg and others (1990) with minor
modifications. Spinach samples were removed from the bags, and
5 g of leaves were immediately homogenized for 1 min in 45 mL of
commercial buffered peptone water (BPW, Difco, Sparks, Md.,
U.S.A.). Decimal dilutions were made in BPW and pour plated using
plate count agar (Difco). The plates were incubated for 2 d at 30 °C
for determination of mesophilic bacteria and for 14 d at 3.3 °C for
psychrotrophic bacteria.
Enzyme activity
Lipoxygenase. The method of Chen and Whitaker (1986) as
modified by Theerakulkait and Barrett (1995) was used. Twenty
grams of spinach leaves and 2 g of polyvinylpolypyrrolidone (PVPP)
were homogenized for 1 min in 40 mL of cold (4 °C) extraction buffer
(0.05 M K2HPO4, 0.05 M citric acid, 0.86 M NaCl, adjusted to pH 6.4
with 2.5 M KOH). The homogenate was filtered through 2 layers of
cheesecloth and centrifuged (4 °C) at 27000 g for 30 min. The
supernatant was kept on ice until analyzed.
For preparation of enzyme substrate, linoleic acid (157.2 L)
(Sigma-Aldrich Milwaukee, Wis., U.S.A.) was mixed with an equal
volume of Tween-20 and 10 mL of distilled water. The mixture was
clarified by adding 1.0 mL of 0.1 N NaOH and brought to volume
with 0.2 M phosphate buffer (pH 7.0) in a 200-mL volumetric flask.
This solution had a final concentration of 2.5 mM linoleic acid. The
substrate solution was allowed to equilibrate to 25 °C for 10 min,
flushed with O2 for 2 min, and 0.9 mL was mixed with 0.1 mL of
enzyme extract. A unit of enzyme activity is defined as that amount
of enzyme that produces a change in absorbance of 0.001/min at
234 nm under the assay conditions.
Peroxidase. The previously described enzyme extract that was
prepared was used for measuring peroxidase activity according to
the procedure of Shue and Chen (1991) with minor modifications.
The substrate was prepared by mixing 558 L of guaiacol (Sigma-
Aldrich) with 194.4 L of 30% H2O2 (Sigma-Aldrich) and brought to
volume with 0.2 M sodium phosphate buffer (pH 6.0) in a 100-mL
volumetric flask to obtain a final concentration of 0.05 M guaiacol
and 0.2 M H2O2. Three milliliters of substrate was mixed with 25 L
of enzyme extract and the reaction at 25 °C was monitored for 3 min
at 420 nm. A unit of enzyme activity is defined as the amount of
enzyme that produces a change in absorbance of 1.0/min at 420 nm
under assay conditions.
Gas composition
O2 and CO2 concentrations in packages of spinach were mea-
sured using Mocon PAC CHECK 450 and 550, respectively, gas an-
alyzers (Modern Controls Inc., Minneapolis, Minn., U.S.A.). Gas
samples (5 or 8 cc, respectively) were withdrawn from a single per-
foration on each package using the automatic sampler mode. Mea-
surements were made at 3 different perforations on each package
and an average value was determined. O2 and CO2 concentrations
in the storage chambers were also measured.
Folate analysis
Total folate in spinach samples was determined by enzymatic
digestion of the tissue matrix to release bound folate vitamers fol-
lowed by microbiological assay using the 96-well microplate proce-
dure described by Tamura (1990) and modified by Pandrangi and
LaBorde (2004). The microbiological method for vitamin quantifica-
tion uses the growth response of folate-dependent Lactobacillus
rhamnosus in food sample extracts that have been enzymatically
treated to release the bound vitamin. Spinach leaves (10 0.01 g)
were homogenized in a blender with 50 mL of 0.1 M phosphate buff-
er containing 114 mM ascorbic acid (Sigma-Aldrich) (final pH 4.1).
The homogenate was heated in a water bath at 100 °C for 10 min and
immediately cooled for storage at –70 °C. Folate was enzymatically
released from the tissue matrix by combining 250 L of the homoge-
nate with an equal volume of 0.3 M citric acid buffer (pH
4.0) and 500
L of protease (20 mg/mL) and then incubating at 37 °C
for 8 h. At the
end of incubation period, protease was denatured by heating the
sample at 100 °C for 5 min in a water bath. After cooling to room tem-
perature (approximately 23 °C), 200 L of protease-treated sample
was mixed with 950 L of 0.3 M phosphate buffer (pH 7.0) and 50 L
of conjugase (from rat serum, Harlan Bioproducts, Indianapolis, Ind.,
U.S.A.) and then incubated at 37 °C for 3 h. Total folate in each en-
zyme-treated sample was determined by microbiological assay us-
ing L. rhamnosus and 5-formyl tetrahydrofolate (5-HCO-H4PteGlu,
calcium salt) as the folic acid standard. Turbidimetric growth after 18
h at 37 °C was compared by measuring absorbance at 490 nm using
a 96-well microplate reader (Model 315, Bio-tek Instruments, Her-
cules, Calif., U.S.A.). Pooled human blood plasma was used as an
internal standard and assay validity was confirmed by determining
the folate content of triplicate samples of infant formula obtained
from the Natl. Inst. of Standards and Technology (standard reference
material nr 1846, NIST, Gaithersburg, Md., U.S.A.).
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Folate and carotenoids in fresh spinach…
Carotenoid and chlorophyll analysis
Sample extraction and high-performance liquid chromatogra-
phy (HPLC) analysis were achieved using the method of Bushway
(1986) modified by Kopas-Lane and Warthesen (1995). Spinach
extracts were prepared by adding 60 mL of cold (4 °C) methanol/tet-
rahydrofuran (1:1 vol/vol) containing 20 g of sodium sulfate and
1 g of magnesium carbonate to 10 g of spinach leaves and homog-
enizing for 1 min in a Brinkmann Polytron (Model PT 10/35, Brink-
mann Instruments Inc., Westbury, N.Y., U.S.A.) at a speed setting of
6. The homogenate was filtered through a Whatman nr 42 filter and
the residue was re-extracted twice. The filtrate was transferred to a
200-mL volumetric flask and diluted to volume with the homoge-
nizing solvent. A 5-mL aliquot was dried under nitrogen, and the
residue was dissolved in 1 mL of methanol. The solubilized pig-
ments were filtered through 0.45-mm Gelman membrane filter
before HPLC injection.
The reverse-phase HPLC system consisted of Waters 510 series
pumps connected to a Waters 717 autosampler (Waters Inc, Milford,
Conn., U.S.A.). The gradient solvent system consisted of 90% ace-
tonitrile/water/methanol (90/5/5, vol/vol) at a flow rate of 1.5 mL/
min reaching 100% methanol in 15 min. Pigments were separated
on a C-18 column (Model 218TP54, Grace Vydac Inc, Hesperia,
Calif., U.S.A.), and spectra were obtained using a Waters 996 pho-
todiode array detector for peak identification at 436 nm. Spectra and
retention times of chlorophyll a and b and trans beta-carotene were
compared with standards (Sigma Aldrich, Milwaukee, Wis., U.S.A.).
All other identifications were based on published spectral informa-
tion (Braumann and Grimme 1981; Quackenbush 1987). Quantities
of total carotenoids and xanthophylls in treated spinach samples
were compared by calculating changes in peak areas for each of the
identified compounds.
Statistical analysis
The data were analyzed within individual temperatures using
Analysis of Covariance. Differences between packaged and un-
packaged samples were analyzed using Dunnett’s test (Minitab,
Minitab Inc., State College, Pa., U.S.A.). Differences at the maxi-
mum storage time at each temperature were compared using 1-way
analysis of variance (ANOVA).
Results and Discussion
Spinach characteristics
Leaves were considered unacceptable for commercial sale when
they became noticeably wilted and curled along the edges with
approximately 5% of the leaves showing signs of yellowing. Shelf life
parameters used in this study are similar to those used by Piagentini
and others (2002) to describe loss of quality in fresh-cut spinach
during refrigerated storage. Based on preliminary visual observa-
tions, spinach was considered commercially unacceptable after 8
d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. These respective
storage times were designated as shelf life values for each temper-
ature and were used as maximum storage times in subsequent ex-
periments.
Changes in visual quality were confirmed by objective measure-
ments. Color differences (E) increased at all storage temperatures
and were most rapid at higher temperatures (Figure 1). However,
after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively, E values
did not significantly (P > 0.05) differ from each other. Gnanasekha-
ran and others (1992) similarly reported that E values for fresh
spinach increased more rapidly under temperature abuse condi-
tions compared with refrigeration.
The total amount of chlorophyll initially contained in spinach
was 332.8 17 and 65.5 5 g/g, respectively. The ratio of chloro-
phyll a to b remained approximately 5:1 throughout the study.
Chlorophyll decreased (P 0.05) with increasing storage time and
degradation was more rapid at higher temperatures (Figure 2). Only
75%, 69%, and 58% of the initial amount remained after storing for
8 d, 6 d, or 4 d at 4 °C, 10 °C, or 20 °C. Results from chlorophyll de-
termination and color change (Figure 2) indicate that chlorophyll
levels at the end of each spinach shelf life at 4 °C, 10 °C, and 20 °C
do not correlate with E values.
Weight loss, caused by evaporative loss of moisture, significant-
ly (P 0.05) increased with storage time and temperature (Figure
3). After 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, fresh weights did
not differ significantly (P > 0.05) from each other. Loss of water
4C 10C
20C
Figure 1 Change in total color (E) of packaged spinach
stored at 4, 10, and 20 °C for up to 8, 6, and 4 d, respec-
tively. Each value represents the mean of 4 determinations
at each temperature SE.
4C 10C
20C
Figure 2 Retention of chlorophyll (%) in packaged spin-
ach stored at 4, 10, and 20 °C for up to 8, 6, and 4 d, re-
spectively. Each value represents the mean of 4 determi-
nations each temperature SE. Initial total chlorophyll con-
tent was 399 18 g/g.
4C 10C
20C
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Folate and carotenoids in fresh spinach…
Figure 3 Fresh weight loss in packaged spinach stored
at 4, 10, and 20 °C for up to 8, 6, and 4 d, respectively.
Each value represents the mean of 10 determinations at
each temperature SE.
through transpiration can be attributed to differences in internal
relative humidity of the tissue with that of the storage chamber,
which remained within a narrow relative humidity range of 55% to
58% at all temperatures. The approximately equal loss of moisture
at the end of the shelf life for each temperature is consistent with
the equally wilted appearance of the leaves at the same storage
times and temperatures.
Microbial populations
Mesophilic and psychrotrophic bacteria populations in stored
spinach are shown in Table 1. The amount of mesophilic bacteria
populations initially contained in packaged spinach varied between
5.0 and 6.0 logs. Garg and others (1990) reported a similar range for
microbial populations in salad vegetables in the packinghouse.
Microbial populations in spinach stored at 4 °C, 10 °C, and 20 °C
increased by 1.6, 1.1, and 2.3 logs, respectively, with final levels
reaching 7.1 to 7.5 logs.
Psychrotrophic populations similarly increased from 3.6 to 5.9
logs initially to a maximum of 6.9 to 7.5 logs. Other studies have
reported similar increases in mesophilic and psychrotrophic bac-
teria on spinach leaves under refrigerated (5 °C to 7 °C) and temper-
ature abuse (10 °C) conditions (Garg and others 1990; Babic and
others 1996; Piagentini and others 2003).
Enzyme activity
Lipoxygenase activity did not significantly (P > 0.05) change
during storage at each of the temperatures studied (data not
shown). However, activity tended to be higher in spinach leaves
stored at 20 °C compared with 10 °C or 4 °C. In contrast, peroxidase
activity increased with storage time for spinach leaves stored at 4 °C
and 10 °C (Figure 4). Increases in peroxidase activity in stored spin-
ach have been reported (Baardseth and von Elbe 1989) although
both enzymes may participate in degradation reactions (Rodriquez-
Amaya 1993).
Gas composition of packages
Concentrations of oxygen and carbon dioxide inside packages
were not significantly (P > 0.05) affected by storage time or temper-
ature (data not shown). Mean O2 and CO2 levels inside the packages
were 20.1% and 0.03%, respectively, and did not significantly
(P > 0.05) differ from air inside the chamber that surrounded the
packages. Fresh vegetables respire during storage and, in sealed
packages, can result in depletion of oxygen and accumulation of car-
bon dioxide (Price and Floros 1993). These results suggest that the
perforated packaging film provided little resistance to diffusion of
gases between the respiring tissue and the atmosphere surround-
ing the bags.
Folate and carotenoid loss
Total folate in packaged spinach samples taken over the entire
experiment ranged between 84 and 225 g/100 g with a mean value
of 160 42 g/100 g. Previous studies have reported folate values
for fresh spinach from 161 to 410 g/100 g (Klein an others 1981;
Mullin and others 1982; Aiso and Tamura 1998; Lin and Lin 1999;
Shrestha and others 2000; Iwatani and others 2003; USDA 2003;
Pandrangi and LaBorde 2004). Lower folate concentrations in fresh
spinach before storage in this study may be the result of intrinsic
differences between spinach cultivars, growing and handling con-
ditions, or by vitamin degradation during minimal processing and
storage (Mullin and others 1982).
Folate levels decreased (P0.05) with increasing storage time
at approximately the same rate for each temperature (Figure 5). Af-
ter 8 d, 6 d, or 4 d at 4 °C, 10 °C, or 20 °C, folate remaining at each
temperature was an average of 53% of the initial amount. Chen and
others (1983) reported that fresh spinach held in a refrigerator (4 °C)
for 7 d showed a 26%, reduction in folate.
All-trans beta-carotene, 9-cis beta-carotene, and the xantho-
phylls neoxanthin, violaxanthin, and lutein were detected in spin-
ach samples (Figure 6). The same carotenoids were reported by
Kopas-Lane and Warthesen (1995). Values for beta-carotene in fresh
spinach before storage ranged from 54 to 127 g/g with a mean
value of 89.7 23 g/g. These values are comparable to other re-
ported ranges of 30 to 82 g/g (Quakenbush 1987; Masrizal and
others 1997; Holden and others 1999).
Total carotenoids in spinach samples, compared at each time by
adding individual HPLC peak areas, decreased (P 0.05) as stor-
4C 10C
20C
Figure 4 Peroxidase (POD) activity of packaged spinach
stored at 4, 10, and 20 °C for up to 8, 6, and 4 d, respec-
tively. Each value represents the mean of 4 determinations
at each temperature SE.
4C 10C
20C
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Table 1 Growth of mesophilic and psychrotrophic bacteria in packaged spinach stored at 4, 10, and 20 °C for up to
8, 6, and 4 d, respectively.
C 1C 2C
Storage Mesophiles Psychrotrophs Storage Mesophiles Psychrotrophs Storage Mesophiles Psychrotrophs
Time Time Time
(d) Log10 CFU/g (d) Log10 CFU/g (d) Log10 CFU/g
0 5.9 A15.5 A 0 6.0 A 5.9 A 0 5.00 A 3.6 A
2 6.4 A 5.5 A 2 7.0 B 7.0 B 1 7.3 B 7.2 B
4 5.7 A 5.3 A 4 7.2 B 7.2 B 2 7.4 B 7.4 B
6 7.5 B 7.4 B 6 7.1 B 7.0 B 3 7.5 B 7.4 B
8 7.5 B 7.5 B 4 7.3 B 6.9 B
1 Values in a column followed by different letters are significantly different (
p
0.05)
bles compared to tissues that are not wilted or damaged (Ezell and
Wilcox 1962; Yang 1985; Price and Floros 1993).
Packaging effect
There were no significant (P > 0.05) differences for all parameters
studied between packaged and unpackaged spinach (data not
Figure 5 Retention of total folate in packaged spinach
stored at 4, 10, and 20 °C for up to 8, 6, and 4 d, respec-
tively. Each value represents the mean of 4 determinations
at each temperature SE.
4C 10C
20C
Figure 7 — Retention of total carotenoids in packaged spin-
ach stored at 4, 10, and 20 °C for up to 8, 6, and 4 d, re-
spectively. Each value represents the mean of 4 deter-
minations at each temperature SE.
4C 10C
20C
Figure 6 Chromatogram of spinach pigments.
age time increased and degraded more rapidly at higher tempera-
tures (Figure 7). After 8 d, 6 d, and 4 d of storage at 4 °C, 10 °C, and
20 °C, respectively, total carotenoids retained were 54%, 61%, and
44% of initial detected levels. All-trans beta-carotene levels ranged
from 84% to 34% of initial levels after storage between 4 °C and 20
°C, respectively (Table 2) and this isomer was more stable than the
9 –cis form. Retention of xanthophylls, determined by comparing
HPLC peak areas, was also enhanced at lower storage tempera-
tures. Mean retention values for the 3 compounds were 44% after 4
d at 20 °C, 59% after 6 d at 10 °C, and 65% after 8 d at 4 °C. Kopas-
Lane and Warthesen (1995) reported comparable losses of beta-car-
otene in spinach stored at 4 °C. However, they did not observe sig-
nificant losses of neoxanthin, violaxanthin, or lutein.
Lower losses of folate (Mullin and others 1982; Chen and others
1983) and carotenoids (Simonetti and others 1991; Kopas-Lane and
Warthesen 1995) have been reported by others using similarly
stored fresh spinach. In these studies, store-bought or field-grown
spinach was used that was sorted immediately before experiments
began to remove damaged or discolored leaves. In the present
study, the entire content of packages of spinach was used and may
have included leaves that had already lost moisture to evaporation
or had been damaged during washing, centrifuging, and packag-
ing. The greater loss of nutrients in this study is consistent with
reports of more rapid quality decline in wilted or wounded vegeta-
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Folate and carotenoids in fresh spinach…
Table 2 — Retention of carotenoids in packaged spinach stored at 4, 10, or 20 °C for 8, 6, or 4 d, respectively.
Carotenoids remaining (%)
Storage All-trans 9-cis
conditions beta-carotene beta-carotene Neoxanthin Violaxanthin Lutein
4 °C / 8 d 84.3 A 49.9 A 65.1 A 69.1 A 61.0 A
10 °C / 6 d 40.9 B 52.4 AB 57.5 A 55.4 AB 65.0 A
20 °C / 4 d 34.3 B 33.4 B 41.5 B 41.3 B 48.3 B
1 Values in a column followed by different letters are significantly different (
p
0.05)
shown). Diffusion of moisture and gasses through the bag perfora-
tions is apparently unimpeded as evidenced by identical fresh
weight losses and gas compositions in packaged and unpackaged
samples. Gas composition in minimally processed vegetables is
known to strongly influence the retention of vitamins and other
quality characteristics during storage (McGill and others 1966; Barth
and others 1993; Barth and Zhuang 1996; Howard and Hernandez-
Brenes 1998). The absence of differences in microbial populations,
chlorophyll loss, color, enzyme activity, and vitamin retention be-
tween packaged and nonpackaged spinach in this study is consis-
tent with the identical fresh weight losses and gas compositions
observed.
Conclusions
Minimally processed vegetables are attractive to consumers
because of their convenience and nutritional value. Howev-
er, substantial losses of folate and carotenoids occurred in pack-
aged spinach under both refrigerated and temperature abuse con-
ditions. Published values for these nutrients in fresh spinach may,
therefore, not always accurately reflect levels that are consumed. It
is, therefore, essential that growers, packers, fresh-cut processors,
and retailers maintain storage temperatures as low as possible to
minimize vitamin losses in fresh spinach. Consumers should keep
fresh spinach refrigerated and use the product as close as possible
to the time at which it was purchased.
References
Aiso K, Tamura T. 1998. Trienzyme treatment for food folate analysis: optimal
pH and incubation time for -amylase and protease treatment. J Nutr Sci Vi-
taminol 44:361–70.
Baardseth P, von Elbe JH. 1989. Effect of ethylene, free fatty acid, and some enzyme
systems on chlorophyll degradation. J Food Sci 54(5):1361–3.
Babic I, Roy S, Watada AE, Wergin WP. 1996. Changes in microbial populations on
fresh cut spinach. Int J Food Microbiol 31:107–19.
Barth MM, Kerbel EL, Perry AK, Schmidt SJ. 1993. Modified atmosphere packaging
affects ascorbic acid, enzyme activity, and market quality of broccoli. J Food Sci
58(1):140–3.
Barth MM, Zhuang H. 1996. Packaging design affects anti-oxidant vitamin reten-
tion and quality of broccoli florets during postharvest storage. Postharvest Biol
Technol 9:141–50.
Braumann T, Grimme LH. 1981. Reverse-phase high-performance liquid chroma-
tography of chlorophylls and carotenoids. Biochim Biophys Acta 637:8–17.
Buescher RW, Howard LR, Dexter P. 1999. Postharvest enhancement of fruits and
vegetables for improved human health. Hortscience 34(7):12.
Bushway RJ. 1986. Determination of alpha and beta carotene in some raw fruits and
vegetables by high performance liquid chromatography. Can J Food Sc Tech
15:165–9.
Cao G, Sofic E, Prior RL. 1996. Antioxidant capacity of tea and common vegetables.
J Agric Food Chem 44:3426–31.
Chen TS, Song YO, Kirsch AJ. 1983. Effects of blanching, freezing and storage on
folacin content of spinach. Nutr Rep Int 28:317–24.
Chen AO, Whitaker JR. 1986. Purification and characterization of a lipoxygenase from
immature English peas. J Agric Food Chem 34:203–11.
Ezell BD, Wilcox MS. 1962. Loss of carotene in fresh vegetables as related to
wilting and temperature. J Agric Food Chem 10:124–6.
Gami DB, Chen TS. 1985. Kinetics of folacin destruction in Swiss chard during
storage. J Food Sci 50:447–9, 453.
Garg N, Churey JJ, Splittstoesser DF. 1990. Effect of processing conditions on the
microflora of fresh-cut vegetables. J Food Prot 53:701–3.
Gnanasekharan V, Shewfelt RL, Chinnan MS. 1992. Detection of color in green veg-
etables. J Food Sci 57(1):146–8, 154.
Herbert V. 1999. Folic acid. In: Shils M, Olson J, Shike M, Ross AC, ed. Nutrition in
health and disease. Baltimore: Williams & Wilkins.
Holden JM, Eldridge AL, Beecher GR, Buzzard IM, Bhagwat SA, Davis CS, Dou-
glass LW, Gebhardt SE, Haytowitz DB, Schakel S. 1999. Carotenoid content of
U.S. foods: an update of the database. J Food Comp Anal 12:169–96.
Howard LR, Hernandez-Brenes C. 1998. Antioxidant content and market qual-
ity of jalapeno pepper rings as affected by minimal processing and modified
atmosphere packaging. J Food Qual 21:317–27.
Howard LR, Wong AD, Perry AK, Klein BP. 1999. Beta-carotene and ascorbic acid
retention in fresh and processed vegetables. J Food Sci 64(5):929–36.
Iwatani Y, Arcot J, Shrestha AK. 2003. Determination of folate contents in some
Australian vegetables. J Comp Anal 16(1):37–48.
Kader AA. 2002. Postharvest biology and technology: and overview. In: Kader AA,
editor. Postharvest technology of horticultural crops. Oakland, Calif.: Univ. of
California Div. of Agriculture and Natural Resources, Spec. Publ. 3311. p 39–48.
Klein BP, Kuo CHY, Boyd G. 1981. Folacin and ascorbic acid retention in fresh raw,
microwave, and conventionally cooked spinach.. J Food Sci 46(2):640–1
Kopas-Lane LM, Warthesen JJ. 1995. Carotenoid photostability in raw spinach
and carrots during cold-storage. J Food Sci 60:773–6.
Lin BF, Lin RF. 1999. Effect of Chinese stir-fry cooking on folate contents of veg-
etables. J Chinese Agric Chem Soc 37:443–54.
Masrizal MA, Giraud DW, Driskell JA. 1997. Retention of vitamin C, iron, and
beta carotene in vegetables prepared using different cooking methods. J Food
Qual 20:(5)403–18.
McGill IN, Nelson AI, Steinberg MP. 1966. Effects of modified storage atmosphere
on ascorbic acid and other quality characteristics of spinach. J Food Sci 31:510–
6.
Mullin WJ, Wood DF, Howsam SG. 1982. Some factors affecting folacin content of
spinach, Swiss chard, broccoli and brussels sprouts. Nutr Rep Int 26(1):7–16.
[NAS] Natl. Academy of Sciences. 1989. Recommended dietary allowances. 10th
ed. Washington, D.C.: Subcommittee on the 10th Edition of the RDAs. Food and
Nutrition Board. Commission on Life Sciences, Natl. Research Council.
Pandrangi S, LaBorde LF. 2004. Optimization of microbiological assay of folic acid
and determination of folate content in spinach. Int J Food Sci Tech 39:1–8.
Paradis C, Castaigne F, Desrosiers T, Fortin J, Rodrigue N, Willemot C. 1996. Sen-
sory, nutrient and chlorophyll changes in broccoli florets during controlled
atmosphere storage. J Food Qual 19(4):303–16.
Piagentini AM, Guemes DR, Pirovani ME. 2002. Sensory characteristics of fresh-
cut spinach preserved by combined factors methodology. J Food Sci 67(4):1544–
9.
Piagentini AM, Guemes DR, Pirovani ME. 2003. Mesophilic aerobic population
of fresh-cut spinach as affected by chemical treatment and type of packaging
film. J Food Sci 68(2):602–7.
Price JL, Floros JD. 1993. Quality decline in minimally processed fruits and veg-
etables. Dev Food Sci 32:405–27.
Quakenbush FW. 1987. Reverse-phase HPLC separation of cis- and trans-caro-
tenoids and its application to beta-carotene in food materials. J Liq Chro-
matogr 10:643–53.
Rodriquez-Amaya DB. 1993. Stability of carotenoids during storage of foods. In:
Charalambous G, editor. Shelf life studies of food and beverages. St. Louis:
Elsevier. p 591–628.
Shewfelt RL, Heaton EK, Batal KM. 1984. Nondestructive color measurement of
fresh broccoli. J Food Sci 49:1612–3.
Shrestha AK, Arcot J, Paterson J. 2000. Folate assay by traditional and tri-enzyme
treatments using cryoprotected Lactobacillus casei. Food Chem 71:545–52.
Shue SC, Chen AO. 1991. Lipoxygenase as blanching index for frozen vegetable
soybeans. J Food Sci 56(2):448–51.
Simonetti P, Porrini M, Testolin G. 1991. Effect of environmental factors and
storage on vitamin content of Pisum sativum and Spinacia oleracea. Ital J
Food Sci 3(4):187–96.
Tamura T. 1990. Microbiological assay of folates. In: Piccian MF, Stokstad ELR,
Gregory JF, editors. Folic acid metabolism in health and disease. Contempo-
rary issues in clinical nutrition. New York: Wiley-Liss. 13:121–37.
Tee ES. 1992. Carotenoids and retinoids in human nutrition. CRC Cr Rev Food
Sci 31:103–63.
Theerakulkait C, Barrett DM. 1995. Lipoxygenase in sweet corn germ: isolation
and physicochemical properties. J Food Sci 60(5):1029–32, 1040.
[USDA] U.S. Dept. of Agriculture, Agricultural Research Service. 2003. Bethseda,
Md.: USDA Natl. Nutrient Database for Standard Reference. Release 16. Nutri-
ent Data Laboratory Home Page. Available from: http://www.nal.usda.gov/
fnic/foodcomp. Accessed 12 Aug 2003.
Wu Y, Perry AK, Klein BP. 1992. Vitamin C and beta-carotene in fresh and frozen
green beans and broccoli in a simulated system. J Food Qual 15(2):87–96.
Yang SF. 1985. Biosynthesis and action of ethylene. Hortscience 20(1):41–5.
... All batches had the same final average value of 28.53 (± 6.56) μg/100 g, which coincided with the report of 39.4 μg/100 g by Irías-Mata et al. (2018). The loss of carotenoids in horticultural products during storage postharvest has been previously reported (Pandrangi and Laborde, 2004). In the present work, fruits that were not at yellow maturity experienced a decrease in the content of carotenoids; however, once they reached the mature stage, concentrations of these compounds remained approximately constant. ...
... On the other hand, the highest carotenoid contents were found at 15°C, and the lowest at 25°C ( Figure 3B). Temperature is a factor that affects carotenoid stability, and a higher thermal condition causes higher loss of these compounds during storage (Pandrangi and Laborde, 2004). ...
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... Conversely, 5-CH 3 -H 4 -folate and H 4 -folate (in diglutamate form) levels slightly increased. O'Hare et al. [39] suggested a possible interconversion among folate forms, after one week of storage, and that the folate losses could be influenced by senescence processes such as moisture loss and leaf degradation (damaging and discolouring) as already observed by Pandangri and LaBorde [40] for spinach. This last observation seemed to be partly confirmed in the present study, where a marked loss of leaves integrity and turgidity in unprocessed/ unpackaged leaves after the third day of storage, as highlighted by sensory analysis, seemed to be associated with the marked reduction on the total folate content. ...
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