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Introduction
Stinging nettle (Urtica dioica, L. Urticaceae) is a ubiquitous
herb which is available in large part of the world. Urtica
dioica is a moderately shade- tolerant species, which occurs
on most moist or damp, weakly acid or weakly basic,
richly fertile soils. Its stems and leaves are densely covered
with Stinging hairs, which release potentially pain- inducing
toxins, is rarely eaten by castles and rabbits (Taylor, 2009).
This species is known as tenacious weeds, able to live
in the toughest conditions, and notoriously known for
inflicting pain. From ancient times, the fresh Stinging
nettle is used for flailing arthritic or paralytic limbs with
fresh Stinging nettle to stimulate circulation and bring
warmth to joints and extremities in a treatment known
as “urtication” (Green, 1820). Ancient Egyptians also re-
portedly used the infusion for the relief of arthritis and
lumbago (Harrison 1966). Above mentioned practice of
urtication or rubefaction became a standard in folk medi-
cine as a remedy for arthritis, rheumatism, and muscular
paralysis and is perhaps the most ancient medicinal use
of Stinging nettle (Upton 2013). Nettle can be used to
foster health and vitality of the people. Due to the nu-
tritional and functional qualities of nettle, it has been
utilized to alleviate symptoms associated with allergic
rhinitis and improve oxidative stability in brine anchovies.
It is also rich in fatty acids, carotenoid, and phenolic
compounds, while its extracts have been reported to im-
prove oxidative stability in brined vegetables (Rutto et al.
2013).
A comprehensive proximate analysis showed the shoots
harvested from Stinging nettle (Shoot) showed close to
90% moisture and rests are proteins (3.7%), fat (0.6%),
ash (2.1%), dietary fiber (6.4%), total carbohydrate (7.1%),
ORIGINAL RESEARCH
Comparison of nutritional properties of Stinging nettle
(Urtica dioica) flour with wheat and barley flours
Bhaskar Mani Adhikari1, Alina Bajracharya1 & Ashok K. Shrestha2
1Department of Food Technology, National College of Food Science and Technology, Kathmandu, Nepal
2Nutrition and Food Science, School of Science and Health, Hawkesbury Campus, University of Western Sydney, Penrith NSW 2751, Australia
© 2015 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc. This is an open access article under the terms of
the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
Keywords
Antioxidant activity, barley flour, nettle
powder, polyphenol
Correspondence
Bhaskar Mani Adhikari, Department of Food
Technology, National College of Food Science
and Technology, Kathmandu, Nepal. Tel:
+977 9841413448; Fax: +977 1 4428724;
E-mails: vaskarmani@gmail.com;
bm.adhikari@nist.edu.np
Funding Information
No funding information provided.
Received: 3 March 2015; Revised: 15 June
2015; Accepted: 17 June 2015
Food Science & Nutrition
2016; 4(1): 119–124
doi: 10.1002/fsn3.259
Abstract
Stinging nettle (Urtica dioica. L) is a wild, unique herbaceous perennial flower-
ing plant with Stinging hairs. It has a long history of use as a food sources as
a soup or curries, and also used as a fiber as well as a medicinal herb. The
current aim was to analyze the composition and bioactive compounds in Nepa-
lese Stinging nettle. Chemical analysis showed the relatively higher level of crude
protein (33.8%), crude fiber (9.1%), crude fat (3.6%), total ash (16.2%), car-
bohydrate (37.4%), and relatively lower energy value (307 kcal/100 g) as com-
pared to wheat and barley flours. Analysis of nettle powder showed significantly
higher level of bioactive compounds: phenolic compounds as 129 mg Gallic
acid equivalent/g; carotenoid level 3497 μg/g; tannin 0.93 mg/100 g; anti- oxidant
activity 66.3 DPPH inhibition (%), as compared to wheat and barley. This study
further established that nettle plants as very good source of energy, proteins,
high fiber, and a range of health benefitting bioactive compounds.
120 © 2015 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
B. M. Adhikari et al.Nutritional Properties of Stinging Nettle
and total calories (45.7 kcal/100 g) (wet basis). Besides,
Stinging nettle (shoot) contains vitamin A, vitamin C,
calcium, iron, sodium, and rich fatty acid profile (Rutto
et al. 2013). Farag et al. (2013) studied the geographic,
taxonomical and morphological diversity, genetics, etc.,
under control conditions. Urtica dioica is the only species
of Urtica to be cultivated commercially for pharmaceutical
purposes, and the commercial extraction of chlorophyll
and stem fibers. He further reported U. dioica as a good
source of flavonoids, phenylpropanoids, and caffeic acid
analogues. Besides, the use of Nettle extract for rheuma-
tism, eczema, allergic rhinitis, and arthritis is well studied
(Harrison 1966; Upton 2013).
Stinging nettle is rarely domesticated due to its sting
but the species remains popular as food and medicines
in poor countries like Nepal (Uprety et al. 2012). From
the centuries, in the foothills of Nepal’s Himalayas, the
Himalayan Stinging nettle has naturally grown in the wild.
Recently, founder of Himalayan Wild Fibers, is in the
process of developing the nettle fiber industry with the
local community. It is expected to help in the develop-
ment of strong fiber that would create work and income
to many Nepalese and bring a durable and sustainable
textile to the market (Tree hugger).
In Georgia, a meal of boiled Stinging nettle seasoned
with walnut is common. Romanians use sour soup made
from fermented wheat bran vegetables and green nettle
leaves harvested from young plants (Costa et al. 2013).
However, one of the most underutilized and neglected
crops are now getting attention on their commercial uti-
lization due to its nutrition and functional properties.
Production and processing of different products from it
will also support to uplift the economic status of the
local people from third world countries (Palikhe 2012).
Stinging nettle is very popular as a vegetable in a range
of countries, particularly among the lower socioeconomic
people. More work is needed to learn the nutritive value
of Nepalese cultivars. Stinging nettle is consumed primarily
as a boiled or cooked fresh vegetable whereby it is added
to soups, cooked as a pot herb, or used as a vegetable
complement in dishes. Although popular in Nepal, there
is almost no study on Stinging nettle (Palikhe 2012).
In Nepal, wheat and barley are two most consumed
cereal grains, after rice. These are the major source of
starch, fiber, proteins, lipid, minerals, etc. Barley grain is
reported to be effective in lowering blood cholesterol be-
cause of its high β- glucan content, 2–9% (Hassan et al.
2012). The recent approval of soluble barley beta- glucan
health claims by the Food and Drug Administration of
the USA for lowering blood cholesterol level could further
boost food product development from barley and con-
sumer interest in eating these food products (Yamlahi
and Ouhssine 2013). Wheat is the staple diet for a majority
of global population, containing carbohydrates, protein,
minerals, B- group vitamins, and dietary fiber, etc. Starch
is the major component of wheat, providing calorie as
well as the inner bran coats, phosphates, and other mineral
salts; the outer bran, the much- needed roughage the in-
digestible portion that helps easy movement of bowels;
the germ, vitamins B and E. Kumar et al. (2011) have
comprehensively reviewed the nutritional content and
medicinal properties of wheat.
Nepal is one of the developing countries in the world
but it is rich in flora and fauna. Stinging nettle is one
of the most popular wild edible plants (WEP) that provide
staple and supplement foods. Often these WEPs become
the top cash income to the local communities which
contribute to food security to the region. However, there
is hardly any work on the composition and nutritional
properties of Stinging nettle in Nepal. Therefore, this work
studied the nutritional and functional properties of sting-
ing nettle dried powder. Besides, this work also compared
the properties of Stinging nettle powder with wheat as
well as barley flour.
Materials and Methods
Raw material collection and preparation
Stinging nettle (Urtica dioica) leaves were collected from
Kirtipur, Nepal. The collected samples were carefully car-
ried afresh to the laboratory for chemical analysis. The
Stinging nettle leaves were cleaned (washed) so that the
foreign particles are removed. The leaves were blanched
for 1 min at 80°C in wet condition. The leaves were then
drained, placed on the trays and so as to remove excess
water. Then the trays were put inside the cabinet drier
for drying at 60°C for 2 days, till the crispy texture was
observed. Dried leaves were ground in a coffee grinder
and sieved through the 80 size mesh making into a fine
Nettle powder as done previously (Palikhe 2012). Barley
and wheat flours were purchased from the local market.
All dried flours were analyzed for moisture content and
transferred into the hermitically sealed container.
Chemical analysis
All three flour samples viz., wheat, barley and Stinging
nettle were immediately analyzed in triplicates. Moisture
content was measured by oven drying at 100°C until the
constant weight was reached. Total crude oil of all three
samples was extracted using hexane in Soxhlet System
HT2 Texator, (Sweden). Total ash values were obtained
by incineration of flour samples for overnight at 550°C
at minimum 6 h (AOAC, 2005). Calcium content was
measured by precipitation as calcium oxalate, dissolving
121
© 2015 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
Nutritional Properties of Stinging NettleB. M. Adhikari et al.
in concentrated sulfuric acid and titration with standard
potassium permanganate (Ranganna 2001). Iron was
determined by converting iron present in foods into ferric
form and treating thereafter with potassium thiocyanate
to form the red ferric thiocyanate which is measured by
colorimetry at 480 nm (Ranganna 2001). Total carbohy-
drate content was measured by the difference method.
All chemical analyses were conducted by the methods as
recommended by Ranganna (2001).
A number of functional properties of above samples
were also analyzed. The antioxidant activity (AA, DPPH
inhibition %) was determined by the method described
by Nuengchamnong et al. (2009). Total polyphenol (TP,
mg GAE/g) and carotenoids were determined as per the
method described by Ranganna (2001). Tannin as an
anti- nutritional factor was determined according to AOAC
(2005).
Data analysis
Data were statistically processed by Gen Stat for analysis
of variance (ANOVA), Microsoft Excel- 2007 for analysis.
Means of data were separated whether they are significant
or not by using LSD (least square difference) method at
5% level of significance.
Results and Discussion
Proximate analysis of raw materials
Wheat and barley flours were purchased from the local
market but nettle was processed into fine powders as
mentioned in the methodology section. The chemical
analyses of wheat flour, barley flour and nettle powder
were carried out and results are presented in dry basis.
The mean values of chemical composition of wheat flour,
barley flour, and nettle powder are presented in Table 1.
The initial moisture content of the leaves was not meas-
ured. However, previous studies have shown that the Nettle
plant contains relatively high level of moisture of, for
example, 89% (Rutto et al. 2013) and 84.4% (Mishra
2007). The moisture content of wheat flour was 12.4%
which is common in commercial wheat flour as previously
reported by Kent and Evers (2004). Barley flour had similar
moisture content, 12.2%. After cabinet drying of leaves
followed by grinding, the moisture content of the Nettle
powder was reduced significantly to 7.0% (Table 1).
Protein content of the ground wheat, barley and Stinging
nettle were 10.6%, 11.8%, and 33.8% (db), respectively.
Analytical data of the nettle powder exhibits about 3 times
protein level as compared to the traditional source of
cereal proteins, that is, rice, wheat, and barley. Previous
study also showed a relatively higher amount of protein
content, 33.6% (dry basis) in the Nettle powder.
Considering a higher level of protein in Nettle powder,
this species expected to supply higher concentrations of
essential amino acids. Besides, it has a better amino acid
profile than most of the other leafy vegetables (Rutto
et al. 2013).
Rutto et al. (2013) has reported relatively higher amounts
of all essential amino acid content in Stinging nettle,
except leucine and lysine. Nettle leaf flour has been in-
corporated in many recipes, for example, bread, pasta,
and noodles dough that suggest it could be used as a
protein- rich supplement in starchy diets associated with
poor and undernourished population like Nepal. As com-
pared to the conventional source of proteins, Nettle powder
contains 3.2 and 2.9 times greater amount of proteins as
compared to wheat and barley flours, respectively. Nettle
powder has one of the richest sources of crude fiber (9.1%,
db) (Table 1). The amount of crude fiber in the nettle
powder is significantly higher than most of the cereals
and other plant foods, more than 9 times higher as com-
pared to wheat and barley flour. Published literatures
showed the Nettle powder has 6.4% (db) crude fiber
(Rutto et al. 2013). The level of crude fat is relatively
low at 3.6% (db), but this value is still higher than wheat
(1.7%) and barley flour (1.7%).
Table 1. Chemical composition of wheat, barley, and nettle powders1.
Parameters Wheat flour Barley flour Nettle powder
Moisture (%) 12.37 ± 0.25 12.2 ± 0.19 7.04 ± 0.77
Crude protein (%,db) 10.6 ± 0.23 11.84 ± 0.09 33.77 ± 0.35
Crude fiber (%,db) 0.65 ± 0.13 1.03 ± 0.08 9.08 ± 0.14
Crude fat (%,db) 1.68 ± 0.23 1.73 ± 0.67 3.55 ± 0.06
Total ash (%,db) 0.56 ± 0.07 3.6 ± 0.08 16.21 ± 0.54
Carbohydrate (%,db) 86.51 ± 0.27 81.8 ± 0.08 37.39 ± 0.72
Calcium (mg/100 g) 18.94 ± 0.08 17.51 ± 0.26 168.77 ± 1.47
Iron (mg/100 g) 3.37 ± 0.29 3.63 ± 0.11 227.89 ± 0.21
db, dry basis.
1Values are mean ± Standard deviation of triplicates.
122 © 2015 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
B. M. Adhikari et al.Nutritional Properties of Stinging Nettle
Stinging Nettle is rich in minerals. Current study showed
the Nettle powder contained 16.2% (db) ash content which
is much higher than conventional cereals (Table 1). Rutto
et al. (2013) reported that the total ash content of Nettle
powder is 19.1% (db) or 2.1% in wet basis. The higher
level of minerals in Nettle is also demonstrated by higher
level of calcium (169 mg/100 g) and iron (277 mg/100 g)
(Table 2). Once again, these values are much higher than
those from wheat and barley flours. USDA data showed
the Nettle powder contains 4% calcium (db), 2.8% (db)
potassium followed by phosphorus, magnesium and traces
of iron, sodium and zinc (USDA, 2008). Based on this
data, Nettle powder probably is one of the richest sources
of minerals among the plant foods. In comparison, wheat
flour and barley flour have much lower total ash content,
0.6% and 3.6%, respectively.
Nettle powder contained the lowest amount of carbo-
hydrate (37.4%, db) as compared to regular cereals, for
example, wheat (86.5%) and barley (81.8%). It shows the
Nettle powder is much less glycemic as compared to the
conventional sources of plant foods such as cereals and
tuber in particular. Table 1 shows the crude fiber (9.1%
db) forms a significant component of Nettle powder. Rutto
et al. (2013) shows the carbohydrate content of Nettle
powder is close to the currently analyzed value, 7.1% db.
The calorific value of wheat flour was higher, that is,
381.9 kcal/100 g than barley flour and nettle powder which
were 369.7 kcal/100 g and 307.2 kcal/100 g, respectively.
This also shows the Nettle powder is low in calorie as
compared to conventional cereals.
Carbohydrate levels in the nettle powder decreases with
increase in the protein content, fiber, ash, and fat as shown
in Table 1. The results agree to the report given by Palikhe
(2012) Thapaliya (2010). Therefore, the current finding
showed that the use of nettle powder and barley in bakery
products likely to increase the protein, ash and fiber
whereas decrease in calorific value as well as increase in
bioactive compound (discussed later). The incorporation
of barley flour in the cereal based food products such as
biscuits, breakfast cereals, noodles, etc., potentially lower
the blood cholesterol, cardiovascular and other diet related
because of soluble β- glucan (Hassan et al. 2012).
Functional properties of raw materials
Nettle plant and its associated products are reported to
be rich in a number of bioactive compounds (Knipping
et al. 2012; Johnson et al. 2013; Rutto et al. 2013). It
has been reported that the natural phenolic compounds
play an important role in cancer prevention and treat-
ment. Phenolic compounds from medicinal herbs and
dietary plants include phenolic acids, flavonoids, tannins,
stilbenes, curcuminoids, coumarins, lignans, quinones, and
others. Various bioactivities of phenolic compounds are
responsible for their chemopreventive properties (e.g.,
antioxidant, anticarcinogenic, or antimutagenic and anti-
inflammatory effects) and also contribute to their inducing
apoptosis by arresting cell cycle, regulating carcinogen
metabolism and ontogenesis expression, inhibiting DNA
binding and cell adhesion, migration, proliferation or dif-
ferentiation, and blocking signaling pathways (Knipping
et al. 2012; Johnson et al. 2013).
Table 2 shows the nettle powder contained relatively
higher level of bioactive compounds, for example, tannin,
total polyphenol (TP), antioxidant activity (AA), carote-
noid, and total caloric value as compared to wheat and
barley flours. The total phenolic content of nettle powder
was 129 mg GAE (Gaelic Acid Equivalent)/g, which is
much higher than the wheat flour (1.3 GAE/g) and barley
flour (1.7 GAE/g). One of the quantitative analysis of
plant phenolics in Nettle plant showed only 21 of the
45 compounds in levels above the reliable quantification
limit (Orcic et al. 2014). Natural phenolic compounds
reported to play important role in cancer prevention and
treatment. A comprehensive review showed the compounds
from medicinal herbs such as Nettle plant and dietary
plants include phenolic acids, flavonoids, tannins, cur-
cuminoids, coumarins, lignans, etc. (Huang et al. 2010).
The carotenoid content of wheat flour, barley flour
and nettle powder were 320, 382.3, and 3496.7 μg/g, re-
spectively. Nettle powder appeared to have almost ten
times higher amount of carotenoid as compared to wheat
flour and barley flour (Table 2). According to Rutto et al.
(2013), the blanched nettle at 98°C for 1 min contained
4689 μg/g amount of carotenoids. It seems that in both
Table 2. Analysis of wheat flour, barley flour, and nettle powder1.
Parameters Wheat flour Barley flour Nettle powder
Tannin content (% as is) ND 0.53 ± 0.03 0.93 ± 0.01
Total polyphenol (mg GAE/g, db) 1.31 ± 0.01 1.76 ± 0.01 128.75 ± 0.21
Antioxidant activity (DPPH inhibition, % as is) 23.72 ± 0.45 28.64 ± 0.03 66.3 ± 0.12
Carotenoids (μg/g, db) 320.05 ± 0.08 382.3 ± 0.56 3496.67 ± 0.56
Calorific value (kcal/100 g) 381.93 ± 0.05 369.68 ± 0.84 307.24 ± 0.13
db, dry basis; ND, not detected.
1Values are mean ± standard deviation of triplicates.
123
© 2015 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
Nutritional Properties of Stinging NettleB. M. Adhikari et al.
cases, the most significant reductions might have occurred
due to the longer exposure to heat during the drying
process. It has been reported that the amount of vitamin
A, iron, and calcium are significantly affected by the heat
(Rutto et al. 2013).
Carotenoids are the precursors of vitamin A and similar
compounds. β- carotene is one of most commonly known
carotenoids which is a potent antioxidant as well as a
dietary factor for growth. It is a precursor of vitamin A
that has important role in vision, as the prosthetic group
of the light sensitive proteins in retina, and a major role
in the regulation of gene expression and tissue differentia-
tion (Bender, 2003). Deficiency of vitamin A is a major
public health problem around the world. The prevention
of vitamin A deficiency is one of the three micronutrient
priorities of the World Health Organization (WHO), oth-
ers are iron and iodine.
Tannins (Polyphenols) occur in cereals, especially in
the seed coat (Reilly et al. 2009). The tannin content of
barley flour and nettle powder was 0.53 and 0.93 mg/100 g,
respectively, whereas, no tannin was observed in the wheat
flour. Polyphenols occur in cereals and these form com-
plexes with proteins and inhibition of digestive enzymes.
Nettle powder had higher level of anti- oxidant activity
of 66.3 DPPH inhibition (%) as compared to wheat flour
23.72 DPPH inhibition (%) and barley flour (28.64 DPPH
inhibition (%). Higher level of antioxidant activity (AA)
was also observed in Nepalese nettle powder. Current
data showed similar amino acid value in Nepalese nettle,
as reported by Thapaliya (2010).
A prospective, randomized, double- blind, placebo-
controlled, crossover study showed the Urtica dioica re-
ported to have beneficial effects in the treatment of
symptomatic benign prostatic hyperplasia (BPH). Further
clinical trials should be conducted to confirm these results
before concluding that Urtica dioica is effective.
Conclusions
Stinging nettle (Urtica dioica) is a common herb and its
stem and leaves are densely covered with Stinging hairs
that inflict pain. It is eaten as a curry, sour soup, vegetable
complement in dish, etc. Stinging nettle has a great me-
dicinal value such as relieve of arthritis, rheumatism, mus-
cular pain, etc. Nettle powder contains high amount of
protein (38%), crude fiber (9%), total ash (16.2%), calcium
(0.17%), iron (0.23%), and relatively low in carbohydrate
(37%). As compared to barley and wheat flour, it has
much higher protein, crude fiber, fat, ash, calcium and
iron, and low in glycemic index. Besides, it has excellent
health enhancing functional properties as compared to
conventional grains. As compared to barley and wheat, it
has much higher level of tannin content, total polyphenol,
antioxidant activity, carotenoids, and lower calorific value.
Bioactivities of these functional components may play im-
portant role in arthritis, rheumatism, muscular paralysis,
potentially cancer prevention, etc.
Conflict of Interest
None declared.
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