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Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 5(7): 111-115
Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 5(7): 111-115 (ISSN: 2141-7016)
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COMPARATIVE EFFECTS OF SPROUTING ON PROXIMATE, MINERAL
COMPOSITION AND FUNCTIONAL PROPERTIES OF WHITE AND YELLOW
SWEET MAIZE (ZEA MAYS VAR SACCHARATA)
Oluwalana, Isaac Babatunde
Department of Food Science and Technology,
Federal University of Technology, Akure. Ondo State, Nigeria.
--------------------------------------------------------------------------------------------------------------Abstract
The effects of sprouting on proximate, mineral composition and functional properties of white and yellow sweet
maize were evaluated. The maize kernels obtained from Agricultural Input Supply Agency, Ministry of
Agriculture, Ado-Ekiti, Nigeria were sorted and divided into two portions. The first portion was soaked for 24
hours after which it was spread on trays lined with cloth and kept wet by frequent spraying of water each
morning and evening for 2 days. The sprouted maize grains were oven- dried at 60ºC to constant weight and
milled into flour. The second portion was processed into flour without sprouting, using the same method. Each
of the portions was analyzed for proximate, mineral compositions and functional properties using standard
methods. Sprouting of both white and yellow sweet maize grains resulted in significant increase (р<0.05) in
crude protein, while the increase in ash is not significant (р>0.05). Conversely, there was significant decrease
(р<0.05) in carbohydrate, fat and crude fibre. With the exception of iron, which was found not to be significant
(р>0.05), all other analyzed minerals (i.e. sodium, potassium, calcium and magnesium) exhibited significant
increase (р<0.05) in the sprouted samples. For the functional properties, both white and yellow varieties of the
sprouted flour samples exhibited decrease in bulk density from 0.670±0.001 to 0.069±0.004 and 0.068±0.001 to
0.067±0.006 respectively. The sprouted flour also had a lower swelling index from 1.290±0.001 to 1.200±0.116
and 1.450±0.001 to 1.300±0.058 for both white and yellow sweet maize. Increase in water absorption capacity
from 1.800±0.058 to 1.810±0.001 for white and 1.590±0.002 to 1.750±0.058 for yellow maize was observed.
The results showed that the sprouting process improved the nutrient composition and enhanced the functional
properties of both white and yellow sweet maize, with the white variety being found to be slightly better
Keywords: effect, sprouting, sweet maize, composition and functional properties
INTRODUCTION
Maize or corn (Zea mays) is a cereal crop that is
grown usually throughout the world in a range of agroecological environment. Introduced into Africa by the
Portuguese in the 16th century, maize has since
become one of the Africa’s most important staple food
crops. Worldwide production of maize is 785million
tons, with the largest producer- the United States of
America producing 42%; Africa 6.5% with Nigeria
being the largest African producer with nearly 8
million tons (Gill, 1980).
Among the cereals, maize represents the staple food
for most part of the population of Africa, Nigeria
inclusive. The kernel is used both for human
consumption and for livestock feed (Ikem, 1991;
Oyarekua and Adeyeye, 2009; Ikem and Amusa,
2010). Maize is eaten either at the green stage, as
boiled or roasted ears, or dried and prepared into a
jelly- like ‘pap’ or ‘eko’ (maize grill) (Alika et al.,
1988). Preparations and uses of the maize grains
varied from group to group in Nigeria, though at times
with some similarities.
Nutritionally, maize is a relatively poor cereal when it
comes to the quality of its protein, because it has
limiting amounts of two essential amino acids, lysine
and tryptophan (Azevedo et al., 1997). Maize grains
are rich in vitamins A, C, and E, carbohydrates,
essential minerals, dietary fibre, and contains 9%
protein (Halley, 1983).
Maize comes in several varieties, such as popcorn,
dent corn, flint corn, waxy corn, amylomaize, flour
maize and sweet maize. Sweet maize (Zea mays var
saccharata) kernels are white or yellow and may be
wrinkled or become caramelized in colour when fully
mature.
Corn flour is an important food ingredient and its
industrial and food uses would increase if appropriate
applications were developed. One way of increasing
uses of raw materials is to promote functional
modifications. As new food systems are developed,
new ingredient modifications and new techniques for
these modifications would be needed. Sprouting
process is known as a way to promote changes in the
biochemical, sensorial and nutritional characteristics
of cereal grains (Lorenz, 1980; Colmenares de Ruiz
and Bressani, 1990; Mora- Escobedo et al., 1991).
Sprouting or germination has been reported to improve
digestibility, bioavailability of vitamins, minerals,
amino acids, proteins and phytochemicals, and
decrease anti- nutrients and starch of some cereals and
legumes ( Asiedu et al., 1992; Helland et al., 2002
and Egli et al., 2004) and thereby improve protein and
iron absorption. Moreover, α-amylase activity is
increased during germination of cereals. This enzyme
hydrolyzes amylose and amylopectin to dextrin and
maltose, thus reducing the viscosity of thick cereal
porridges without dilution with water while
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Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 5(7): 111-115 (ISSN: 2141-7016)
simultaneously enhancing their energy and nutrient
densities (Gibson et al., 1998).
measuring cylinder was recorded. Both the volume
and mass of the flour sample were determined.
The objective of this study is to compare and contrast
the effect of sprouting on the nutritional and functional
properties of white and yellow sweet maize.
Swelling Capacity (SC)
The swelling capacity was determined as described by
Leach et al. (1959) with modifications for small
samples. One gram of the flour sample was mixed
with 10ml distilled water in a centrifuge tube and
heated at 80ºC for 30mins. It was continually shaken
during the heating period. After heating, the
suspension was centrifuged at 500rpm for 30mins. The
supernatant was decanted and the weight of the paste
taken. The swelling power was calculated as: Swelling
power = weight of the paste/weight of dry flour.
MATERIALS
The yellow and white sweet maize kernels (Zea mays
var saccharata) were purchased from Agricultural
Input Supply Agency, Ministry of Agriculture, AdoEkiti, Ekiti State, Nigeria.
METHODS
Sample Preparation
Yellow and white sweet maize grains were sorted and
divided into two portions. The first portion was soaked
for 24 hours after which it was spread on trays lined
with cloth and kept wet by frequent spraying of water
at every morning and evening for 2 days. The sprouted
maize grains were oven- dried at 60ºC to constant
weight and milled into flour in hammer mill.
MINERAL COMPOSITION
Mineral composition namely: K, Ca, Fe, Na and Mg
were determined by wet ashing method (AOAC,
2005). Sodium and Potassium were determined using
a flame photometer as described by AOAC (2005).
Calcium, iron and magnesium of the flour were
determined using x- ray Fluorescence (XRF).
The second portion was processed into flour without
sprouting, using the same method. The seed flours
were labeled as follows:
UYM: Unsprouted Yellow Maize flour
SYM: Sprouted Yellow Maize flour
UWM: Unsprouted White Maize flour
SWM: Sprouted White Maize flour
STATISTICAL ANALYSIS
All samples were in three replicates. The statistical
analyses were conducted using one- way ANOVA
procedures. Statistical differences in samples were
tested for at р<0.05. Duncan’s new Multiple- Range
Test (DNMRT) was used to separate the mean values.
All analyses were done with SPSS (11.0) software.
ANALYSIS
Proximate Composition
The proximate analysis for the sweet maize flour
samples were carried out using Association of Official
Analytical Chemists (AOAC, 2005) methods.
Carbohydrate was estimated by subtracting the ash,
protein, crude fibre and fat percentages from 100%.
RESULTS AND DISCUSSION
Proximate Composition
The results of the proximate composition of the
sprouted and raw white and yellow sweet maize (Zea
mays var saccharata) are shown in table 1 below.
DETERMINATION
OF
FUNCTIONAL
PROPERTIES
Water Absorption Capacity
Water absorption capacity (WAC) of the flours was
determined by the method of Beuchat et al., (1977).
Ten milliliter (10 ml) of water was added to 1.0 g of
each sample in a beaker. The suspension was stirred
for 5 minutes at 1000 rpm on magnetic stirrer hot
plate, after which it was transferred into centrifuge
tubes and centrifuged at 3500 rpm for 30 minutes; the
volume of the supernatant obtained was measured. The
density of the water was assumed to be 1g/ml. The
water absorbed by the seed flour was calculated as the
difference between the initial water used and the
volume of the supernatant obtained after centrifuging.
Bulk Density (BD)
The bulk density of the maize flours was determined
by the method of Okaka and Potter (1979) with
modification. A specified quantity of the sample of
each of the differently processed maize flour was put
into an already weighed 10 ml measuring cylinder.
The cylinder was tapped continuously until a constant
volume was obtained. The new mass of the sample and
112
Comparatively, the protein content of both white and
yellow sprouted sweet maize were significantly
(р<0.05) higher than that of the unsprouted maize
samples. This could be as a result of mobilization of
stored nitrogen of maize to aid sprouting. It may also
be as a result of synthesis of enzymes or a
compositional change following the degradation of
other constituents. This observation is consistent with
the findings of Malleshi et al., (1989) who reported
significant increase in protein content of weaning food
formulated from sprouted cereals. Other prominent
researchers have also observed significant increase in
protein content with seed sprouting (Enujiugha et al.,
2003; Fasasi, 2009; Ijarotimi and Keshinro, 2011).
The observed reduction in carbohydrate, crude fibre
and crude fat contents with germination could be due
to their utilization as energy sources in the sprouting
process (Fasasi, 2009; Ijarotimi and Keshinro, 2011).
The lipolytic enzymes hydrolyze fats to simpler
products during sprouting, which can be used as a
source of energy for the developing embryo. The
reduction in fat content is of particular interest as
maize oil is reported to be rich in essential fatty acids
(Adeyemo et al., 1992) which play a very important
role in the proper development of brain cells in infants
and children. Thus if germination adversely affects the
quantity of essential fatty acids of the grains, the need
Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 5(7): 111-115 (ISSN: 2141-7016)
for supplementation becomes more crucial. This
decrease in fat content also implies an increased shelflife for the sprouted seeds compared to the unsprouted
ones. The ash content also increased with sprouting as
similarly observed by Obasi et al. (2009). In general,
white sweet maize tend to have slightly more crude
protein, crude fat and crude fibre than the yellow type,
while the yellow type is slightly richer in ash and
carbohydrate.
Table 1: Effect of Sprouting on the Proximate Composition (%) Dry weight of Sweet white and yellow maize
(Mean + SE)
Samples
Moisture (%)
Protein (%)
Fat (%)
Ash (%)
Fibre (%)
Carbohydrate (%)
Energy (Kcal)
UWM
6.29+0.006
10.23b+0.133
4.21a+0.121
2.16+0.092
2.90a+0.006
79.80b+0.058
400.87b+0.006
SWM
6.13+0.069
12.34a+0.069
3.89ab+0.035
2.24+0.127
1.89a+0.064
77.90d+0.127
402.94a+0.186
UYM
6.16+0.064
10.00b+0.005
4.20a+0.116
2.18+0.064
2.89a+0.064
80.73a+0.069
400.72c+0.116
SYM
6.16+0.069
12.13a+0.075
3.88b+0.005
2.27+0.127
2.69b0.005
79.03c+0.017
399.56d+0.116
Values are means of triplicate determinations. Mean values in the same column followed by dissimilar letters
are significant at P<0.05.
Key:
FUNCTIONAL PROPERTIES
UWM: Unsprouted white maize.
The results of the functional properties of the
UYM: Unsprouted yellow maize.
unsprouted and sprouted white and yellow sweet
SWM: Sprouted white maize.
maize flours (Zea mays var saccharata) are shown in
table 2.
SYM: Sprouted yellow
Table 2: Effect of Sprouting on functional properties of white and yellow sweet maize flour
Samples
UWM
SWM
UYM
SYM
Bulk density
0.069b ± 0.004
0.670a ± 0.001
0.068b ± 0.001
0.067b ± 0.006
Mean ± S.E.
Swelling capacity
1.290ab ± 0.001
1.200b ± 0.116
1.450a ± 0.001
1.300ab ± 0.058
Water absorption capacity
1.800a ± 0.058
1.810a ±0 .001
1.590b ± 0.002
1.750a ± 0.058
Oil absorption capacity
0.552c±0.001
0.736b±0.002
0.551c±0.001
0.920a±0.001
Values are means of triplicate determinations. Similar superscript along columns are not significantly different
(p>0.05)
Key: UWM: Unsprouted white maize, SWM: as much. Swelling capacity can be an index of
Sprouted white maize, UYM: Unsprouted yellow stickiness of the resultant product.
maize, SYM: Sprouted yellow maize
There was an increase in both water and oil absorption
The raw flour had a higher bulk density than the capacity with sprouted flour taking up more water and
sprouted one. This could be because sprouting tend to oil. This increased solubility could be as a result of the
soften the seeds, thus making milling easier, with increase in amount of soluble sugars present in the
smaller particle sizes than unsprouted grain, hence the sprouted flour. Flours with better water absorption
reduction in bulk density. The significance of this is capacity are easier to reconstitute in water when
that the less bulky flours will have higher nutrient needed. Eneche (2009) also reported an increase in
density, since more flour can be packaged in the same water absorption with soaking of maize grains. Oil
given volume. The raw flour also had a higher absorption capacity is important since oil acts as flavor
swelling index than that of sprouted flour. This could retainer and increases the palatability of foods
be as a result of the swelling of the starch granules, (Kinsella, 1976).
which leads to disruption of some of the
intermolecular hydrogen bonds, thus allowing more MINERAL COMPOSITION
water to enter and enlarge the granules (Ihekoronye The values of mineral composition of raw and
and Ngoddy, 1985). The sprouted flour, whose sprouted white and yellow sweet maize flour are
starches had already been dextrinized, could not swell shown in table 3.
Table 3: Mineral Composition (mg/100g) of raw and sprouted yellow and white sweet maize
Samples
UWM
SWM
UYM
SYM
Iron
(mg/100g)
0.180± 0.006
0.210 ± 0.064
0.190 ± 0.058
0.270 ± 0.635
Mean ± S.E.
Sodium
(mg/100g)
10.42b±0.237
11.56a ± 0.127
10.44b ± 0.127
11.65a ± 0.191
Potassium
538
(mg/100g)
113.70c ± 0.305
132.00b ± 0.035
114.01c ± 0.006
134.70a ± 0.310
Calcium
(mg/100g)
0.150± 0.065
0.360± 0.127
0.210 ± 0.064
0.350 ± 0.069
Magnesium
(mg/100g)
24.12c ± 0.069
27.11b ± 0.064
24.13c ± 0.075
28.01a ± 0.006
Values are means of triplicate determinations. Similar superscripts along columns are not significantly different
(p>0.05)
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Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 5(7): 111-115 (ISSN: 2141-7016)
AOAC (Association of Official Analytical Chemists)
2005. Official methods of analysis of the Association of
analytical chemists international, 18th ed. Gathersburg,
MD USA official methods 2005. 08.
Key: UWM: Unsprouted white maize, SWM: Sprouted
white maize, UYM: Unsprouted yellow maize, SYM:
Sprouted yellow maize
The mineral contents of the sprouted seeds flour were
comparatively higher than that of raw seeds flour. This
corroborated with earlier report by Inyang and Zakari
(2008). The desirable changes in the nutrient contents
may be due to the breakdown of complex compounds into
simpler forms. The metabolic activity of resting seeds
increases as soon as they are hydrated during soaking.
Complex biochemical changes occur during hydration
and subsequent sprouting. The reserved chemical
constituents are broken down by enzymes into simple
components that are used to make new compounds. In
general, both raw and sprouted yellow sweet maize tend
to be richer in minerals than the white one.
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CONCLUSION
This study concluded that germination of both white and
yellow sweet maize resulted in the enhancement of its
nutritional quality as observed by the significant increase
in quantity of protein, reduced bulk and increased nutrient
density. These observations could be advantageously
utilized to improve nutrition of infant and children foods,
particularly in the developing countries, where maize is
consumed in large quantity as well as for food products
development in food industry. The associated reduction
in carbohydrate and fat can be compensated for by
blending with flours of other legumes/oil seeds.
Egli I, Davidsson L, Zeder C, Walczyk T, Hurell R. 2004.
Dephytinization of a complementary foods based on
wheat and soy increases zinc, but not copper apparent
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grains
during
soaking.
Proceedins
of
the
AGM/conference (AGMC’ 09), Nigerian Institute of
Food Science and Technology, Yola, pp 41- 42.
BIOGRAPHY
Dr. Isaac Babatunde OLUWALANA is an Associate
Professor (Reader) at the Department of Food Science
and Technology, Federal University of Technology,
Akure, Ondo State, Nigeria. His area of specialization is
Post Harvest Technology. His research works have
produced solutions to colossal losses of fresh fruits and
vegetables as the shelf/ green life of many of them can
now be extended by periods ranging from 2 weeks to
about 2 months with adaptable and inexpensive methods.
Dr. Oluwalana has over 45 academic publications in both
international and local journals. He is a Consultant to
many government and private organizations. He has
about 10 years of Industrial and 20 years of Academic
Experience. He has travelled extensively to many nations
for business and academic purposes. Dr. Oluwalana is
happily married with children.
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