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VOL. X, ISSUE XXXIV, JULY 2020 MULTILOGIC IN SCIENCE ISSN 2277-7601
An International Refereed, Peer Reviewed & Indexed Quarterly Journal in Science, Agriculture & Engineering
PEARL MILLET: A FUNDAMENTAL REVIEW ON UNDERUTILIZED SOURCE OF NUTRITION
Monika Satankar
1*
, Amit Kumar Patil
2
, Sheshrao Kautkar
3
and Utkarsh Kumar
4
1
PhD Scholar, Division of Agricultural Engineering, ICAR- IARI, (New Delhi)
monikasatankar94@gmail.com
2
Scientist, ICAR-Indian Grassland and Fodder Research Institute, Jhansi, (Uttar Pradesh)
amitpatilbetul@gmail.com
3
Scientist, GTC ICAR-Central Institute for Research on Cotton Technology, Nagpur (MH)
sskautkar15@gmail.com
4
Scientist, ICAR-VPKAS, Almora (UK)
utkarsh.mail.id@gmail.com
(MS Received: 25.06.2020; MS Revised: 29.07.2020; MS Accepted: 30.07.2020)
MS 2590 (RESEARCH PAPER IN AGRICULTURAL ENGINEERING)
Abstract
Pearl millet is an important cereal crop as it is rich in nutrition with capability to grow at harsh climacteric condition. A sudden climate
changes and other natural disasters can create food security problem which raises the price of foods and also reduces the availability of
food materials. In this condition pearl millet is an alternative nutritious crop for the poor men which provide enough nutrition for active and
healthy life. It is cheap source of nutrition when compared to other major cereal crops. While having its nutrition and health benefits,
utilization of this crop is restricted due to some anti-nutrition factors and poor keeping quality. Therefore, the aim of this review is to provide
the information about nutritional profile, processing techniques, health benefits, products and problem of pearl millet in order to bring the
great potential of this important small grain to producers and consumers.
Keywords: Pearl millet, health benefits, millet processing, food products
Introduction
Pearl millet (Pennisstum glaucum ) is multipurpose cereal crop
belongs to the Poaceae family. It is commonly called as Bajra,
Bajri, Sajje, Kambu, Kamban, Sajjalu etc in variour Indian local
languages. It is commonly used for food, feed, and forages purpose
(Arora et al., 2003). This millet cultivated mostly in semi-arid part
of Africa and Asia. In India, pearl millet is a third most important
crop grown after rice and wheat. It is grown on 7.4 million ha area
with an average production of 9.13 million tonnes during 2017-18
(Project Coordinator Review, 2019). The major pearl millet
growing states are Rajasthan, Maharashtra, Gujarat, Uttar Pradesh
and Haryana which accounts for 90% acreage in the country (Singh
et al. 2018).
Fig. 1 Pearl millet crop in the field
This crop has a capability to grow at very high temperature with
low water requirement where other crops like rice, wheat, maize
fail to grow. It has also advantageous physiological characteristics
when compared to other cereals as it is resistant to drought, low
soil fertility and high salinity (Rai et al., 2008). Pearl millet grain
content 75% endosperm, 17% germ, and 8% bran (Serna-Saldival
and Rooney, 1995).The pearl millet germ proportion is thus about
twice that of sorghum, it is a factor that contributes to the higher
nutritive value of pearl millet grain (Andrew and Kumar 1991).
Because of the higher content of nutrition value, pearl millet is
notified as one of the millet under “Nutri-Cereals” by the
Agriculture ministry, Government of India (GOI).
Pearl millet is a good source of energy, protein, vitamins, dietary
fibers and minerals. It is high in fat and better fat digestibility than
other cereals. This is also high in unsaturated fatty acids with higher
content of nutritionally important n-3 fatty acid. Among all the
millets, pearl millet has highest content of macronutrients and
significantly rich in resistant starch, soluble and insoluble dietary
fibers (Antony et al. 1996; Ragaee et al., 2006). Pearl millet
effectively helps in maintaining the blood sugar level constant in
diabetes patient for long period of time (Dayakar Rao et al. 2017).
Thus the nutritional composition and health benefits attracted
today’s market focused present health segment highlighting
commercial viability of the crop. Therefore the main objective of
this article is to explore nutritional quality, health benefits,
processing techniques, problems and product of pearl millet grain
so as to use it for further research in the area of post harvest
processing and value addition of pearl millet crop.
Nutritional value of pearl millet
Pearl millet has deep root system so it extract soil nutrient and holds
higher nutritional value than the other cereal crops such as wheat,
rice, maize and sorghum. Mineral-wise, this crop contain high
amount of iron, zinc, magnesium, copper, manganese, potassium
and phosphorous. It is good source of energy, with calorific value of
361 Kcal/100g and high in fiber content (1.2g / 100g) (Singh et al.
2018). Protein content in pearl millet is higher (Tylor and
Emmabux, 2008) and it is also a good source of vitamin-B,
Vitamin-A, folic acid, calcium and magnesium (Pattanashett et al.
2016). Pearl millet grain has high fat content than other cereal cause
poor keeping quality of the product. The chemical composition of
pearl millet along with other traditional cereal crops is given in
Table 1 (Chapke et. al., 2018).
Table 1 Nutritional composition of staple cereals (per 100 g)
Staple cereals Protein
(g)
Carbohydrate
(g)
Fat (g) Crude fiber
(g)
Mineral
matter (g)
Calcium
(mg)
Phosphorus
(mg)
Sorghum
10.4
72.6
1.9
1.6
1.6
25
222
Pearl millet
11.6
67.5
5.0
1.2
2.3
42
296
Finger millet
7.3
72.0
1.3
3.6
2.7
344
283
Foxtail millet
12.3
60.9
4.3
8.0
3.3
31
290
VOL. X, ISSUE XXXIV, JULY 2020 MULTILOGIC IN SCIENCE ISSN 2277-7601
An International Refereed, Peer Reviewed & Indexed Quarterly Journal in Science, Agriculture & Engineering
Barley
11.5
696
1.3
3.9
1.2
26
215
Maize
11.5
66.2
3.6
2.7
1.5
20
248
Wheat
11.8
71.2
1.5
1.2
1.5
41
306
Rice
6.8
78.2
0.5
0.2
0.6
10
160
Health benefits of pearl millet
Pearl millet is helpful to patients with diabetes as it has a relatively
low glycemic index that helps to digest gradually and produce
glucose at a slower rate than other foods (Asp, 1996). This can
sustain long periods of stable blood sugar levels. Pearl millet grain
contains phenolic compounds in pericarp and grain testa, in
particular flavonoids, which inhibit tumor production (Huang and
Ferraro 1992). It is high in iron and zinc content which may help in
increasing HB and also preventing from anemia disease (Vanisha et
al., 2011). Pearl millet grain is gluten-free, and it is one of the
alternatives for the patients who have celiac diseases to consume a
gluten free diet for a normal and healthy lifestyle (Jukanti et al.
2016). Pearl millet has a large amount of phosphorus. Phosphorus is
very essential for bone growth and development as well as for
development of ATP which is the energy currency of our body
(Malik, 2015). The pearl millet lignin and phytonutrients serve as
good antioxidants and thus prevent heart related diseases. For this
reason, pearl millet is considered good for cardiac health (Dayakar
Rao et. al., 2017).
Products of pearl millet
Pearl millet cereals are used to produce various conventional foods.
Most widely available traditional pearl millet include porridge and
flatbreads (Roti). Other foods are also available in market such as
alcoholic beverage (opaque beer or Dogon millet beer, chibuku
shake, mbeg, merissa) and non-alcoholic drink (pombe, pito, boza,
kunun Zaki, bushera, mahewu, oskikundu, marewa) (Adebiyi et. al.,
2018). Pearl millet flour is traditionally used by Indian housewives
to prepare variety of different products like Laddoo, chips, wadi,
bread, cake etc. These products are shown in Fig. 2.
1. Pearl millet grains 2. Flour 3. Flatbread (Roti)
4. Laddoo 5. Chips 6. Wadi
7. Cake 8. Puri 9. Bread
Fig. 2 Various products prepared from pearl millet
Effect of processing techniques on pearl millet
Pearl millet contains rich nutrients as more to the major cultivated
cereal crops. However, major factors which restrict its utilization
are the presence of anti-nutritional factors (phytate, tannins and
polyphenols) which reduce availability of minerals. Pearl millet
having poor keeping quality due to the presence of lipase activity
which affects the acceptability of the product in market (Savita rani
et. al., 2018). The researchers therefore, more concentrate on the
effect of various processing techniques to enhance nutrient
composition and shelf life of pearl millet. Those processing
techniques are described below;
Decortication: It is a mechanical operation to remove pericarp and
bran layer from the pearl millet grain. It reduces an anti-nutritional
factor phytate, tannin and polyphenols also some minerals and
vitamins, but the process enhance the bioaccessability of minerals.
Decortication improves the colour and palatability of the processed
product. Various researchers have studied the effect of decortication
on nutrient composition of pearl millet. Goyal et. al., (2017)
VOL. X, ISSUE XXXIV, JULY 2020 MULTILOGIC IN SCIENCE ISSN 2277-7601
An International Refereed, Peer Reviewed & Indexed Quarterly Journal in Science, Agriculture & Engineering
www.ycjournal.net NAAS Rating- 5.20 1083
observed the impact of decortication on phytate content in pearl
millet grains and concluded that phytate deposition occurs in the
endosperm and bran fractions but is substantially denser in
endosperm fractions than bran fraction. Tiwari et. al., (2014)
studied the effect of pre-milling treatments on storage stability of
pearl millet flour and it was found that during pearling for 5 to 30
min, the pearled content from the grain varied from 16 to 34%.
Their findings are clear that phytic acid, total polyphenol, iron and
zinc decreased as the pearling period increased. El Hag et. al.,
(2002) Examined dehulling effect on two (Standard and Ugandi)
pearl millet cultivars. Their results showed that both varieties had
substantially lowered the protein, polyphenols as well as phytic acid
contents after dehulling due to removal of outer layers.
Blanching: Blanching is one of the most effective pre-milling
procedures for enhancing the shelf life of final product. It could be
slow down the enzymatic activity without having much effect on its
nutritional composition. Dashrath Bhati et. al,. (2016) found that 90
s of blanching treatment may be used for the product development
because of high in- vitro iron 3.29 mg/100grams, great reduction in
free fatty acid content (20.57) and for improving the color of pearl
millet. Singh et. al., (2006) showed that blanching reduce inhibitory
factors, rancidity, and bitterness in biscuits prepared from pearl
millet. Archana et. al., (1998) reported when blanched at 98 °C for
30 sec, pearl millet showed a substantial reduction in polyphenols
(from 764.45 to 544.45 mg/100 g) and phytic acid content (from
833.42 to 512.10 mg/100 g) that could be due to the leaching of
polyphenols and phytate ions into the soaking medium under the
influence of gradient concentration.
Milling: Milling is the process of separating endosperm, bran and
germ. This practice converts endosperm into small and fine
particles to facilitate the production of fine flour. Hammer mill and
roller mill can be used for reducing the particle size. Milling is used
to process pearl millet flours with different particle size distribution,
but it causes the release of fatty acids present in the germ that are
susceptible to oxidation and thus decreases the shelf life of the flour
(Tiwari et. al., 2014). Abdelrahman et. al., (1983) studied on roller
mills can be used for the production of low fat pearl millet grits.
This process was accompanied by decorticating, tempering and
milling of the grains through finely corrugated rolls which rotate in
opposite direction and resulted in an average yield of 61% grits
(from whole grains) with 1.2% fat content. According to a study
conducted by Pushparaj and Urooj (2011), two cultivars of pearl
millet (Kalukombu and Maharashtra Rabi Bajra) when subjected to
milling (whole flour, bran rich fraction and semi-refined flour)
showed higher percentage of in vitro protein digestibility found in
bran rich fraction. These finding showed that tannin might not only
be responsible for lower protein digestibility and various factors
such as interaction of proteins with non-protein components and
proteins themselves can also affect protein digestibility
Heat treatments: Heat treatment is one of the most important pre-
milling treatments in case of pearl millets before development of
convenience food because it has very less shelf life and helps as an
important driver to increase its utilization on a day-to-day basis.
Yadav et. al., (2012) stated that microwave heating at a moisture
level of 18% for 80 s reduced lipase activity of pearl millet flour
may be due to the high temperature of the sample (107.6 ºC) by
converting microwave energy into thermal energy. In addition,
microwave- treated flour that is suitable for up to days of storage
(15-35 ºC) packed in LDPE than the control flour that only has a
shelf life of 10 days. Dashrath Bhati et. al., (2016) noted that the
iron bio availability was maximum at 100°C for 120 minute-DHT
(63.47%). Tiwari et al. (2014) investigated that heat treatment (pre-
treatments) significantly reduced phytic acid by 43.68%, and
polyphenol but had no significant reduction in iron and zinc.
Ezhilarasi and Nazni (2018) concluded that thermal pre-milling
treatments roasting (110º C for 60 sec) and boiling (1:1 grain is to
water) in a pan for 15 min enhanced the functional attributes of
pearl millets and significantly lowered the anti-nutrients namely
tannin and trypsin inhibitor activity while the bioavailability of
pearl millet nutrients increases.
Problems associated with pearl millet
Despite rich in high nutritive value, its shelf life is limited because
high content of lipid in the grain. Pearl millet can be stored for
longer periods without significant quality adjustments if the kernel
remains intact (Kaced et. al., 1984; Kachare and Chavan, 1992) but
the quality of the meal deteriorates rapidly once the grain is
decorticated and ground. Deterioration occurs because the fat
content with highly active lipases contributes to hydrolysis of fats
resulting in rancidity of the pearl millet product causing unpleasant
odor and taste. Both hydrolytic and oxidative changes are reported
in the lipid of the flour, resulting in release of free fatty acids and
formation of peroxide, causing rancidity and bitterness (Kaced et.
al., 1984). Therefore the pearl millet flour cannot be stored for long
period of time and also become a problem for women to grind flour
on daily basis. Rancidity also limited the commercial use of pearl
millet product. Thus, research is needed to increase shelf life of
pearl millet products.
Conclusion
Pearl millet is a staple food with superior nutritional value and
health benefits. As consumers are more attentive towards their
health so the pearl millet has one of the alternative options for
nutritious food. Despite high nutrition value and health benefits, use
of pearl millet is limited because high lipid content which reduce
the shelf life and acceptability of pearl millet products. Some
methods are described to process pearl millet but more detailed
research is needed to assess the real potential and availability of this
“nutri-cereal” to improve the quality of pearl millet product. Non
thermal and other novel techniques are required to develop
improved process protocol for enhancing shelf life and retaining
essential nutrient in the pearl millet product.
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www.ycjournal.net NAAS Rating- 5.20 1084
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