Journal of the Science of Food and Agriculture
J Sci Food Agric 83:945–950 (online: 2003)
DOI: 10.1002/jsfa.1427
Chickpea leaves as a vegetable green for
humans: evaluation of mineral composition
Hayriye Ibrikci,† Sharon JB Knewtson and Michael A Grusak∗
USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX
77030, USA
Abstract: Chickpea (Cicer arietinum) is generally consumed as a seed food, being a good source of
protein and other essential human nutrients. However, young chickpea leaves are also eaten as a cooked
vegetable green in certain parts of the world and could be a useful source of dietary nutrients, especially
in malnourished populations. Because little information is available on the mineral content of this food,
we characterised leaf mineral concentrations in 19 diverse accessions of chickpea. Both desi and kabuli
chickpea types were studied. All plants were greenhouse-grown and were fertilised daily with a complete
mineral solution. Young, fully expanded leaves (fourth through seventh nodes from the apex) were
harvested at both early and late vegetative stages. The leaves were dried, ashed and analysed for mineral
concentrations. Macronutrient mineral (Ca, Mg, K, P) concentrations varied from 1.3-fold to 1.8-fold
and micronutrient mineral (Fe, Zn, Mn, Cu, B, Ni) concentrations varied from 1.5-fold to 2.4-fold across
all accessions. No major differences were observed in leaf mineral concentrations between the kabuli
and desi types; mineral concentrations were generally lower in leaves collected at the later harvest date.
Microscopic analyses demonstrated that all accessions contained crystal inclusions, suggestive of calcium
oxalate crystals. Overall, chickpea leaves were found to be a good source of several minerals required
by humans, and the levels of most of these minerals significantly exceeded those previously reported for
spinach and cabbage.
Published in 2003 by Society of Chemical Industry‡
Keywords: chickpea; leafy vegetables; kabuli; desi; minerals; human nutrition; calcium oxalate; food composition
INTRODUCTION
Chickpea (Cicer arietinum L) is the third most
important cool-season food legume after common
bean (Phaseolus vulgaris L) and pea (Pisum sativum L),
based on world production estimates.1 It is cultivated
in the Indian subcontinent, North Africa, the Middle
East, Southern Europe, Asia, the Americas and
Australia. In several developing countries, chickpea
serves as a staple food for humans and can account
for a significant proportion of daily caloric and
nutrient intake.2 Unfortunately, malnutrition and
micronutrient deficiencies are prevalent in many
chickpea-consuming regions,3 even though chickpea
seeds are a good source of protein and can provide
several essential minerals.4 The nutritional problems
stem from inadequate overall food intake, along with a
low density of micronutrient minerals within the diet.
New sources of nutrient-dense foods would be helpful,
therefore, in the effort to alleviate these problems.5 – 8
Although chickpea is predominantly consumed as a
seed food, young leaves of the plant are also cooked
and consumed as a vegetable green in India and
Nepal.9,10 Green vegetables rich in vitamins, minerals and various health-beneficial phytochemicals can
play an important complementary role in an otherwise
nutrient-incomplete diet.11 For chickpea leaves, data
on leaf mineral concentrations are limited;9,11 however, available reports on Fe, Zn and Cu suggest that
this food could be a good source of these minerals.11
More information is needed on the concentrations of
all the human essential minerals in chickpea leaves,
and whether certain types and/or cultivars of chickpea
might be more nutritious than others.
Cultivated chickpeas are divided into two types
according to colour and relative size of the seeds.
Kabuli chickpeas are large-seeded with a beigecoloured seed coat and are grown throughout most
of the world. Desi chickpeas are small-seeded with a
light- to dark-brown-coloured seed coat and are grown
mainly in India and Africa. Mineral composition data
for seeds of kabuli and desi chickpea have been
reported12 – 14 and some type differences in mineral
∗ Correspondence to: Michael A Grusak, USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of
Medicine, 1100 Bates Street, Houston, TX 77030, USA
E-mail: [email protected]
† Current address: Department of Soil Science, Çukurova University, 01330 Adana, Turkey
‡ This is a U.S. Government work and is in the public domain in the U.S.A.
Contract/grant sponsor: US Department of Agriculture, Agricultural Research Service; contract/grant number: 58-6250-6-001
(Received 7 August 2002; revised version received 8 January 2003; accepted 25 February 2003)
Published in 2003 by Society of Chemical Industry. J Sci Food Agric 0022–5142/2003/$30.00
945
H Ibrikci, SJB Knewtson, MA Grusak
composition have been noted. It is not known,
however, whether the kabuli and desi types might
have different mineral values as vegetable greens.
To gain a better understanding of the potential value
of chickpea leaves as a source of dietary minerals for
humans, we evaluated leaf mineral concentrations in
19 chickpea accessions, comprising both kabuli and
desi types. Plants were grown in a greenhouse with
complete mineral nutrition under controlled environmental conditions in order to observe the genetic
potential for leaf mineral accretion in each of the
selected lines. In this paper we report the mineral concentrations of these lines and discuss the nutritional
value of this food relative to other green vegetables.
MATERIALS AND METHODS
Plant material and growth conditions
Nineteen accessions of Cicer arietinum (Table 1)
were obtained from the USDA germplasm collection
(USDA/ARS Western Regional Plant Introduction
Station, Pullman, WA, USA) for this study. All
accessions were reported to have similar flowering
times (66–69 days after planting); nine of the
accessions were of the kabuli type and 10 were of
the desi type.
Plants were grown in 5 l black plastic pots filled with
a 2:1 (v/v) mixture of synthetic soil (Metro-Mix 360;
Scotts-Sierra Horticultural Products Co, Marysville,
OH USA) and vermiculite (Strong-Lite Medium Vermiculite, Sun Gro Horticulture Co, Seneca, IL, USA).
The growth medium was brought to approximate
field capacity with deionised water prior to planting. Plants of each accession were grown in six pots,
with plants thinned to three seedlings per pot 4 days
after emergence. Pots were randomly assigned positions in the greenhouse. An automated drip irrigation
system was used to deliver 56.5 ml of nutrient solution
Table 1. Chickpea accessions used for leaf mineral analyses
Accession no
Type
Source
PI 357654
PI 360162
PI 360244
PI 360690
PI 426190
PI 426561
PI 451143
PI 451199
PI 451649
PI 359313
PI 359697
PI 359746
PI 359841
PI 359916
PI 360667
PI 360673
PI 450577
PI 450670
PI 450843
Kabuli
Kabuli
Kabuli
Kabuli
Kabuli
Kabuli
Kabuli
Kabuli
Kabuli
Desi
Desi
Desi
Desi
Desi
Desi
Desi
Desi
Desi
Desi
Yugoslavia
Iran
Iran
Turkey
Afghanistan
Pakistan
Iran
Iran
Israel
India
India
India
India
India
Mexico
Morocco
India
India
India
946
to each pot, twice a day. The nutrient solution contained the following concentrations of mineral salts:
1.0 mM KNO3 , 0.4 mM Ca(NO3 )2 , 0.1 mM MgSO4 ,
0.15 mM KH2 PO4 , 25 µM CaCl2 , 25 µM H3 BO3 ,
2 µM MnSO4 , 2 µM ZnSO4 , 0.5 µM CuSO4 , 0.5 µM
H2 MoO4 , 0.1 µM NiSO4 and 1 µM Fe(III)-N, N ethylenebis[2-(2-hydroxyphenyl)glycine] (Sprint 138;
Becker-Underwood, Inc, Ames, IA, USA).
The environmental conditions within the greenhouse were a temperature regime of 22 ± 3 ◦ C day
and 20 ± 3 ◦ C night and relative humidity ranging
from 45 to 65% throughout the day/night cycle. Sunlight was supplemented with metal halide lamps set to
a 15 h day/9 h night photoperiod (lights on at 07:00),
ensuring a minimum intensity of photosynthetically
active radiation of 200 µmol photons m−2 s−1 at the
top of the plants.
Plant sampling and tissue analysis
Young, fully expanded leaves (fourth through seventh
nodes from the apex of the main stem) were harvested
for analysis. Four leaves from each plant (ie a total
of 12 leaves per pot) were harvested at an early
vegetative stage (33 days after planting) from three
pots of each accession, and from three other pots
at a late vegetative stage (61 days after planting, just
prior to the initiation of flowering). The 12 leaves
from each pot were combined and dried at 65–70 ◦ C
for a minimum of 48 h. Leaf samples were weighed,
dry ashed, resuspended in ultrapure nitric acid and
analysed for Ca, Mg, K, P, Fe, Zn, Mn, Cu, B and
Ni concentrations using inductively coupled plasma
atomic emission spectrometry (IRIS Advantage ICPAES; Thermo Elemental, Franklin, MA, USA). Dry
ashing was performed in quartz tubes, with samples
ashed for 6 h at 450 ◦ C. After cooling, to ensure
complete oxidation of all tissues, 2.5 ml of 300 g l−1
H2 O2 was added to each tube and the samples were
reheated to 450 ◦ C for 1 h. Apple leaf standards (SRM
1515; National Institute of Standards and Technology,
Gaithersburg, MD, USA) were ashed and analysed
along with chickpea samples to verify the reliability of
the procedures and analytical measurements. Mineral
values were determined with the ICP-AES using the
following spectral emission lines (nm): Ca, 184.0; Mg,
285.2; K, 769.8; P, 177.4; Fe, 238.2; Zn, 213.8; Mn,
260.5; Cu, 324.7; B, 208.9; Ni, 231.6.
To determine the presence or absence of crystal
inclusions in leaves, a separate set of fully expanded
leaf samples (third fully expanded leaf from the apex)
was taken from a minimum of three plants of each
accession at two vegetative stages (33 and 61 days
after planting) and during the seed development
stage (approximately 90 days after planting). Ten
leaflets were collected from each accession; chlorophyll
was cleared from the samples with five changes
of acetone. Leaflet samples were rehydrated with
deionised water and immediately placed on a glass
microscope slide, under a coverslip. The presence,
location and dimensions of crystal inclusions were
J Sci Food Agric 83:945–950 (online: 2003)
Nutritional value of chickpea leaves as a vegetable green
determined in six randomly chosen leaflets from each
accession using a compound microscope (Optiphot2; Nikon Microscopes, Melville, NY, USA) equipped
with polarising optics. Birefringent crystals, observed
with polarised light, were presumed to be crystals of
calcium oxalate based on their morphology and size.15
Statistical analysis
Reported leaf mineral concentrations are the mean
±standard deviation of three independent samples
of each accession. Statistical comparisons of group
means were performed with an unpaired t-test (Excel
97 software; Microsoft Corp, Seattle, WA, USA).
RESULTS
Mineral concentrations were determined in leaf
samples (fourth through seventh nodes from the
shoot apex) from nine kabuli and 10 desi chickpea
accessions collected at two vegetative time points (33
and 61 days after planting). For the macroelements,
mineral concentrations across accessions (within a
given type or harvest date) varied by as much as
1.5-fold for Ca, 1.8-fold for Mg, 1.3-fold for K and
1.5-fold for P. With respect to the microelements,
leaf mineral concentrations across accessions (within
a given type or harvest date) varied by as much as 1.8fold for Fe, 2.1-fold for Zn, 2.4-fold for Mn, 2.3-fold
for Cu and 1.5-fold both for B and Ni.
Within each harvest date, few differences in mean
mineral concentration were observed between the
kabuli and desi accessions (Table 2). For the day 33
harvest, only Fe and Zn were significantly higher in the
kabuli accessions relative to the desi accessions. With
respect to the day 61 harvest, mean concentrations
of Ca, B and Ni were significantly higher in the desi
accessions relative to the kabuli accessions. Across
the two harvest dates, and within each chickpea
type, mineral concentrations were generally lower
in leaves collected at the later time point (Table 2).
Exceptions to this tendency were seen for Ca (similar
concentrations for the desi type at each time point;
higher day 61 concentrations for the kabuli type) and
Ni (statistically similar concentrations for the desi type
at each time point).
In addition to the mineral characterisation, microscopic studies were conducted to assess the potential
for crystal inclusions (presumed to be calcium oxalate
crystals) in leaves of the chickpea accessions. Crystals
were observed along the vascular bundles in the leaves
of all accessions at all three harvest dates. No crystals
were detected within the interveinal mesophyll tissues.
Across all accessions the observed crystals were prismatic in shape15 and averaged 17.0 ± 2.5 µm in length
by 8.5 ± 1.2 µm in width.
DISCUSSION
Nineteen chickpea accessions were grown under
controlled greenhouse conditions with complete
nutrient fertilisation in order to characterise the
mineral nutritional value of young leaves as a food
Table 2. Mineral concentrations in kabuli and desi chickpea leaves (fourth through seventh nodes from apex) harvested 33 and 61 days after
planting
Ca
Mg
K
P
Fe
Zn
g kg−1 DM
Mn
Cu
B
Ni
86.8a
57.6
139.4
28.3
8.3a
5.0
11.2
2.1
55.9a
45.3
61.9
6.4
7.9a
6.4
9.3
1.0
mg kg−1 DM
Day 33 harvest
Kabuli accessions, n = 9
Mean
Minimum
Maximum
Standard deviation
17.4a
13.5
20.6
2.5
4.9a
3.5
6.2
0.7
41.7a
34.1
45.6
3.5
6.0a
5.1
7.6
0.8
143.6a
103.0
186.5
27.4
125.0a
81.9
163.1
29.9
Desi accessions, n = 10
Mean
Minimum
Maximum
Standard deviation
17.1a
13.1
19.0
2.1
5.1a
4.2
5.7
0.5
41.6a
37.0
47.8
3.8
6.3a
5.3
7.2
0.6
118.5b
102.6
154.8
14.8
107.0ab
74.6
114.9
21.8
60.7b
47.2
88.3
11.2
7.7a
5.2
10.2
1.5
57.2a
48.0
69.4
6.9
8.1a
6.9
10.6
1.1
Day 61 harvest
Kabuli accessions, n = 9
Mean
Minimum
Maximum
Standard deviation
17.1a
14.4
21.4
2.6
3.7b
3.2
4.3
0.5
37.2b
33.1
42.6
2.8
4.9b
4.4
5.4
0.3
99.1c
89.8
119.7
9.8
96.3bc
79.7
137.4
18.4
59.4b
47.1
94.5
14.8
2.2b
1.3
3.0
0.6
64.7b
49.6
76.7
8.2
6.6b
5.5
7.8
0.9
Desi accessions, n = 10
Mean
Minimum
Maximum
Standard deviation
19.9b
16.1
22.6
2.0
4.1b
3.6
4.6
0.3
37.4b
35.1
39.8
1.8
4.7b
4.3
5.1
0.2
92.0c
79.3
103.5
6.7
79.0c
55.9
114.6
19.2
63.0b
52.0
75.8
8.3
2.3b
1.6
3.0
0.5
74.8c
60.4
83.1
6.9
7.4a
6.1
8.5
0.7
Mean values in the same column followed by different letters are significantly different at p ≤ 0.05.
J Sci Food Agric 83:945–950 (online: 2003)
947
H Ibrikci, SJB Knewtson, MA Grusak
source for humans. Although variation was observed
in mineral concentrations amongst the accessions,
no major differences were seen between the two
chickpea types, kabuli and desi (Table 2). Previous
studies investigating mineral composition in seeds of
chickpea did find differences, especially for Ca,13,16
but this could also have been related to kabuli vs
desi differences in seed size.14 The concentrations
observed for all minerals in this study were within the
acceptable ranges reported for mature leaves from
other species.17,18 Thus it appears that all plants
in this study were provided a sufficient supply of
mineral nutrients and that each accession was able to
demonstrate its full genetic potential for leaf mineral
accretion.
Differences in leaf mineral concentration were
observed between the two harvest dates, with most
mineral concentrations being lower in leaves collected
at the day 61 time point (Table 2). It should be stressed
that leaves at each harvest were collected from the
fourth through seventh nodes (from the shoot apex)
and thus a different population of leaves was collected
at day 61 relative to day 33. Plants were much bigger at day 61 and it is possible that the partitioning
of root-absorbed nutrients throughout the larger shoot
mass of the older plants may have led to a lower overall
delivery of nutrients to the terminal leaves. However,
it should also be realised that no assessment of actual
leaf age was made for the leaves collected at either
harvest date (eg the number of days that leaves were
fully expanded prior to harvest). Because leaf age will
impact the net accretion of certain minerals,17 it is
possible that the day 61 leaves were developmentally
younger than the day 33 leaves. Alternatively, wholeplant influx of certain minerals may have declined
with plant age,19 such that the mineral concentrations
within younger leaves were reduced accordingly.
Because the focus of this study was on chickpea
leaves as a food source, we were interested in assessing
their nutritional value relative to other leafy vegetables.
In order to make a food-relevant comparison, we combined data for the kabuli and desi accessions on a fresh
weight basis and calculated mean mineral content for
a 100 g serving size (Table 3). Values for young chickpea leaves harvested at 33 and 61 days after planting
are presented along with database-derived values20 for
two common leafy vegetables, spinach and cabbage.
For either harvest date a serving of chickpea leaves
contained higher amounts of most minerals relative to
the other vegetables. In particular, the Ca content in
chickpea leaves was over three times higher than that
in spinach and over six times higher than that in cabbage. The contents of K and P were also significantly
higher in chickpea leaves, especially when compared
with cabbage.
With respect to leaf calcium content, we also
assessed whether this mineral was immobilised in crystallised form within each of the accessions. Legumes
are known to contain calcium oxalate crystals,21,22
and chickpea leaves in particular have previously been
reported to contain this type of crystal.23,24 The presence or absence of precipitated calcium oxalate is
important from a nutritional standpoint, because this
form of Ca has low bioavailability in the human
gut.25,26 Microscopic analyses verified that all accessions contained prismatic crystals along the vascular
bundles, with crystal sizes being comparable to those
of other legumes.21,22 It is presumed that these crystals
contained Ca and most probably were composed of
calcium oxalate.15 Although we did not determine the
proportion of total Ca associated with these crystals,
their presence makes it probable that a large part of
the leaf Ca would be poorly absorbed. Further studies
are needed to determine the specific bioavailability of
Ca in chickpea leaves.
Leaf concentrations of B and Ni were also measured in this study. Currently, these minerals have
not been confirmed as essential nutrients for humans,
although there is circumstantial evidence in support of
their essentiality.27 The B content in chickpea leaves
(100 g serving; Table 3) was four- to eightfold higher
than that reported for broccoli (Brassica oleracea L,
Italica group) and kale (Brassica oleracea L, Acephala
group).28 Similarly, the Ni content in chickpea leaves
Table 3. Mineral concentrations (mg) in 100 g serving sizes (fresh weight)a of chickpea leaves harvested 33 and 61 days after planting, of raw
spinach (Spinacea oleracea L) leavesb and of raw cabbage (Brassica oleracea L, Capitata group) leavesb
Chickpea 33 days
Chickpea 61 days
Spinach
Cabbage
Mineral
Mean
SE
n
Mean
SE
n
Mean
SE
n
Mean
SE
n
Ca
Mg
K
P
Fe
Zn
Mn
Cu
B
Ni
310
90
749
111
2.4
2.1
1.3
0.1
1.0
0.1
9.3
2.5
14.8
2.9
0.10
0.11
0.10
0.01
0.03
0.00
19
19
19
19
19
19
19
19
19
19
334
70
672
86
1.7
1.6
1.1
trace
1.3
0.1
10.9
1.7
9.4
1.2
0.04
0.08
0.05
0.00
0.04
0.00
19
19
19
19
19
19
19
19
19
19
99
79
558
49
2.7
0.5
0.9
0.1
5.0
4.8
28.7
3.5
0.52
0.04
0.05
0.01
9
7
10
7
10
7
6
7
47
15
246
23
0.6
0.2
0.2
trace
2.3
1.6
9.2
1.6
0.15
0.01
0.02
0.00
37
30
30
35
30
39
49
49
a
b
Water content in leaves (g kg−1 ): chickpea, 820; spinach, 916; cabbage, 916.
Values derived from Ref 20. SE, standard error of the mean; n, number of samples for each analysis.
948
J Sci Food Agric 83:945–950 (online: 2003)
Nutritional value of chickpea leaves as a vegetable green
was two- to threefold higher than that found in 100 g
servings of these same two vegetables.28
In summary, our analysis of 19 diverse chickpea
accessions using controlled greenhouse conditions
demonstrates that young leaves can contain high levels
of several minerals, comparing favourably with other
common leafy vegetables. Under field conditions, soil
nutrient availability and other environmental factors
could lower the leaf concentrations of some minerals;17
nonetheless, chickpea leaves show great promise as
a dietary source of several human essential minerals, especially for populations where malnutrition and
micronutrient deficiencies are prevalent.29 Based on
what is known about nutrient composition in chickpea and other leafy vegetables,11,20 the consumption
of chickpea leaves should also provide a number of
vitamins and health-promoting phytochemicals such
as folate, phylloquinone (vitamin K), ascorbate (vitamin C), β-carotene (a source of vitamin A) and other
carotenoids (which can serve as antioxidants).30 The
consumption of chickpea leaves should be promoted
in areas where chickpea is produced as a staple grain,
although additional field-based studies are needed to
determine what impact, if any, the harvesting of young
leaflets will have on final seed yield.31
ACKNOWLEDGEMENTS
This work was supported in part by the US
Department of Agriculture, Agricultural Research
Service under Cooperative Agreement Number 586250-6-001. The contents of this publication do not
necessarily reflect the views or policies of the US
Department of Agriculture, nor does mention of trade
names, commercial products or organisations imply
endorsement by the US Government.
The authors would like to express their appreciation
to Crystal Burgett and Valeria Musetti (USDA/ARS
Children’s Nutrition Research Center, Houston,
TX, USA) for assistance in the assessment of
calcium oxalate crystals, to Lucia Tyler and John
Edelman (Department of Horticulture Nutrient and
Element Analysis Laboratory, Cornell University,
Ithaca, NY, USA) for mineral analyses, to Clarice
Coyne and Dave Stout (USDA/ARS Western Regional
Plant Introduction Station, Pullman, WA, USA) for
providing the chickpea germplasm, and to Jagdish
Kumar (International Crops Research Institute for
the Semi-Arid Tropics, Patancheru, India) for useful
suggestions that led to the execution of this study.
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