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J. Agric. Food. Tech., 1(6) 101-105, 2011
© 2011, TextRoad Publication
ISSN 2090 – 424X
Journal of Agriculture and Food
Technology
www.textroad.com
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Corresponding Author:
Okoth Judith Kanensi, Department of Food Science and Technology, Jomo Kenyatta University of
Agriculture and Technology, Nairobi. Email: kanensi@gmail.com +254733950524
Optimization of the Period of Steeping and Germination for Amaranth
Grain
Okoth Judith Kanensi1; Sophie Ochola2; Nicholas. K. Gikonyo3; Anselimo Makokha4
1,4 Department of Food Science and Technology, Jomo Kenyatta University of Agriculture and Technology,
P.O.BOX 62000-00200, Nairobi.
2Department of Foods, Nutrition and Dietetics, Kenyatta University, P.O.Box 43844-00100, Nairobi.
3Department of Pharmacy and Complementary /Alternative Medicine, Kenyatta University, P.O.Box 43844-00100, Nairobi.
ABSTRAC
T
According to Kenya Demographic Health Survey, 7% of children under five years were wasted with 16% of
them being underweight probably an indication of poor and inappropriate feeding practices. The children
suffer from protein energy malnutrition (PEM) and micro-nutrient deficiencies which may lead to physical,
mental and motor development retardation. Children are most at risk of PEM during the introduction of
complementary foods usually thin porridge prepared predominantly from cereals and starchy tubers. Such
porridge is low in energy and nutrient density, and may be high in anti-nutrients, despite the fact that infants at
this stage of rapid development have high requirements of energy and nutrients per unit body weight. There is
need therefore to develop appropriate nutrient-dense complementary foods that could be used by low income
families. Amaranth grain has high biological value proteins and a better amino acid profile than nearly all
cereals. It is also rich in essential fatty acids. However it is not commonly used as a complementary food in
Kenya. The main objective was to determine the optimum steeping and germination time for amaranth grain.
The grains were steeped and germinated for various time periods. The dry matter loss, proximate composition
and some antinutrient levels were determined. Dry matter loss was least in amaranth grain steeped for 5 hours
and germinated for 24 hours. At p<0.05, there were no significant differences in ash, fat and protein contents
with respect to steeping and germination time. The crude fiber content and the invitro protein digestibility
varied with different steeping and germination time. The tannin and phytate contents could not be detected
after steeping and germination. Based on dry matter loss and reduction in antinutrient levels, steeping
amaranth grain for 5 hours and germinating for 24 hours were the optimum processing times.
Key words: Complementary foods Nutrient density Processing Antinutrients Protein Energy Malnutrition.
INTRODUCTION
National level estimates show that 35% of children in
Kenya underfive years old are stunted, 7% are wasted
and 16% are undernourished [1]. The children fail to
reach their full potential growth and development, and
suffer long term deprivation of energy and nutrients
and consequently chronic PEM, often accompanied by
micronutrient deficiencies. KDHS (2010) also reported
that the most commonly used foods given to
breastfeeding children under age 3 include food made
from grains (72%), vitamin A rich fruits and vegetables
(53%) and other milk (51%). The most commonly used
first complementary food for babies in Kenya is porridge
[2]. Most families often depend on inadequately
processed traditional foods consisting mainly of
unsupplemented cereal porridges made from maize,
sorghum and millet. These staples may not contain
adequate energy and nutrients. These staples are plant
based. Plant-based diets are often associated with
micronutrient deficits, exacerbated in part by poor
micronutrient bioavailability [3]. Therefore the children
may develop PEM and micro-nutrient deficiencies.
There is currently, a lot of interest in the amaranth
plant, whose leaves are eaten as a vegetable in many
parts of Kenya. Amaranth seed contains more protein
than other grains such as wheat, maize, rice and
sorghum. It contains high levels of minerals especially
iron, phosphorus, magnesium, vitamin A and E. It is
highly recommended for infants because of its high
protein digestibility, absorption and retention by the
baby`s body system. Amaranth has satisfactory lysine
and tryptophan contents. However it is not commonly
used in complementary food preparation. A number of
traditional food processing technologies such as
germination and lactic acid fermentation have been
proposed as a means to improve nutrient density of
complementary foods [4]. There is a chance that
amaranth grain could produce a nutrient dense
complementary food. However there is need to develop
processing methods that would enhance the nutrient
availability in the amaranth grain. This would enable
promotion of its use with recommended processing
methods for achievement of maximum nutrient density.
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J. Agric. Food. Tech., 1(6) 101-105, 2011
Objectives
To determine the optimum steeping and germination
time for amaranth grain.
MATERIALS AND METHODS
Raw materials
Amaranth grain were purchased from Meru County. The
aim was so that the grains could be bought from the
same farmers for consistency in the nutritional value.
Determination of dry matter loss
Samples were accurately weighed in to large petri-
dishes and distilled water added at a ratio of 2:1. They
were steeped for 5, 10, 15, 20 and 24 hours
respectively. Then the petri dishes were covered with
aluminium foil and kept in the dark at 300C. They were
removed from the germination chamber at the set times
(every 24 hours) and transfered in to the drying oven in
the dishes used for germination in order to minimize on
leaching losses. They were dried in an oven at 1050C
until constant weight (AOAC method 925.10) [5]. The
difference between the dry matter of the unsoaked and
the ungerminated samples and that of the steeped and
germinated grains was considered as loss in dry matter.
Steeping and germination
Amaranth grain samples were weighed in to a clean
gauze. They were steeped for 5 hours, 10 hours, 15
hours, 20 hours and 24 hours. After steeping for the
respective time periods, they were germinated for 24,
48 and 72 hours respectively. They were then dried in
an incubator at 500C and milled in to fine flour (200
mesh).
Determination of chemical composition of
amaranth grain
The samples were analysed for protein (Kjeldahl),
moisture (air oven), fat(soxlet), crude fibre according
AOAC (1995). A nitrogen to protein conversion factor
of 6.25 was used. Carbohydrates were determined by
difference and the ash content (muffle furnace) AOAC
(1995).
Determination of antinutrients in the amaranth
grain
Tannin content was determined using the Vanillin-
Hydrochloric acid method [6], [7] [8]. Phytates were
determined the method by Camire and Clydesdale [9].
Protein digestibility was carried out using Mertz et al
[10] procedure with slight modification.
RESULTS
Effect of germination on dry matter
For all the treatments of amaranth grain, there was an
increase in the loss of dry matter with increase in
steeping and germination time as shown by Figure 1.
The amaranth grain samples steeped for 5 hours had
the lowest loss in dry matter.
Figure 1: The effect of steeping and germination times on dry matter loss in amaranth grain
Effect of steeping and germination on the chemical composition of amaranth grain
Table 1 : The effect of steeping and germination time on the proximate composition of amaranth grain (dwb1)
Treatment of amaranth grain % Moisture % Ash % Fat % Protein %Carbohydrate % Crude Fibre
Ungerminated 9.0 ± 0.2 2.7
0 8 ± 0.6 15.4 ± 0.9 64.9 4.3±0.1
Steeping 5 h germ 24 h 5.8 ± 0.6 2.0 ± 0 8.6 ± 0.4 16.6 ± 0.2 67 3.9 ± 0.3
Steeping 5 h germ 48 h 6.3 ± 0.2 2.8 ± 0 8.6 ± 0.5 18.9 ± 0.0 63.4 3.7 ± 0.9
Steeping 5 h germ 72 h 5.0 ± 0.6 3.1 ± 0 9.1 ± 0.7 13.6 ± 0.2 69.3 3.4 ± 0.6
Steeping 10 h germ 24 h 6.8 ± 0.0 2.0 ± 0.1 7.3± 0.3 16.4 ± 0.0 67.5 5 ± 0.6
Steeping 10 h germ 48 h 6.6 ± 0.0 1.8 ± 0 7.3± 0.3 12.5 ± 0.5 71.8 4.4 ± 0.5
Steeping 10 h germ 72 h 6.3 ± 0.1 1.3 ± 0 8.3± 0 13.4 ± 0.2 70.7 4.0 ± 0.5
Steeping 15 h germ 24 h 6.5± 0.0 2.7 ± 0.1 11± 0.5 20.3 ± 0.1 59.5 6 ± 1.3
Steeping 15 h germ 48 h 6.6 ± 0.3 2.2 ± 0.2 8.7±0.4 14.1 ± 0.9 68.4 4.2 ± 0.7
Steeping 15 h germ 72 h 7.7 ± 0.1 2.7 ± 0 8.4±0.5 16.8 ± 0.8 64.4 8.5 ± 0.4
Steeping 20 h germ 24 h 7.2 ± 0.2 2.2 ± 0.1 8 ± 0.4 14.3 ± 0.9 68.3 5.5 ± 0.2
Steeping 20 h germ 48 h 6.6 ± 0.2 1.8 ± 0.2 8.2 ± 0.2 15.5 ± 0.3 67.9 6.2 ± 0.5
Steeping 20 h germ 72 h 5.5 ± 0.3 2.5 ± 0 7.4± 0.3 15.1 ± 0.9 69.5 6.7 ± 0.5
Steeping 24 h germ 24 h 4.5 ± 0.6 2.0 ± 0 9.3± 0.3 10.9 ± 0.9 73.3 2.5 ± 0.9
Steeping 24 h germ 48 h 5.9 ± 0.2 3.3 ± 0 8.1± 0 10.9 ± 0.9 71.8 5.4 ± 0.9
Steeping 24 h germ 72 h 5.9 ± 0.1 2.6 ± 0 8.4± 0.4 20.0 ± 0.9 63.1 5.4 ± 0.4
dwb1 : Dry weight basis Germ: germination h: hours
102
Kanensi et al., 2011
Table 2: The effect of steeping and germination on some antinutrients in amaranth grain (dwb1)
Treatment of amaranth grain Tannins (% Catechin
equivalents CE)
Phytate
(mg per 100 g)
Invitro protein
digestibility (IVPD)
(%)
Ungerminated 0.8 7.9 77.6
Steeping 5 h germ 24 h ND ND 93.2
Steeping 5 h germ 48 h ND ND 93.2
Steeping 5 h germ 72 h ND ND 93.1
Steeping 10 h germ 24 h ND ND 99.2
Steeping 10 h germ 48 h ND ND 93.4
Steeping 10 h germ 72 h ND ND 97.4
Steeping 15 h germ 24 h ND ND 87.8
Steeping 15 h germ 48 h ND ND 94.9
Steeping 15 h germ 72 h ND ND 97.2
Steeping 20 h germ 24 h ND ND 97.2
Steeping 20 h germ 48 h ND ND 96.7
Steeping 20 h germ 72 h ND ND 94.7
Steeping 24 h germ 24 h ND ND 89.4
Steeping 24 h germ 48 h ND ND 81.5
Steeping 24 h germ 72 h ND ND 97.8
dwb1 Dry weight basis
ND Not detected
DISCUSSION
Effect of steeping and germination on the dry
matter of amaranth grain
The greater the germination time, the more the
grains sprouted therefore increasing consumption of
nutrients and increasing the dry matter loss. At
p<0.05 level of significance there were interactions
between steeping and germination time for the
amaranth grain. Long germination periods resulted
in significant losses in dry matter through respiration
which is undesireable [4]. Wijngaard et al [12]
reported that increase in steeping time increased
malting losses. He further reported that steeping
losses are mainly due to three factors: displacement
of dust, dissolving of materials from the grain by
leaching and metabolic activity of the grain,
releasing CO2 and small amounts of ethanol.
Malting losses result from leaching of compounds
from grain during steeping, respiration of the grain
and fermentative processes and the removal of
rootlets [12]
Effect of steeping and germination on the
proximate composition of amaranth grain
The ash content is almost similar to the amount got
by other researchers. The ash content of amaranth
cruentus was reported as 3.2% on dry weight basis
[12], [13]. Ruiz and Bressani [14] reported that the
ash content in ungerminated amaranth grain is 3.0%.
Ruiz and Bressani [14] reported that there were no
changes in ash content with respect to germination
time.The ungerminated amaranth grain had a fat
content of 8% dry weight basis. At p<0.05, there
were no significant differences in fat content with
regard to steeping and germination time. Ruiz and
Bressani [14], reported that the fat content in
ungerminated amaranth crentus is 7.1% on dry
weight basis. According to Ruiz and Bressani [14]
there was no significant change in fat content
extracted using ether during germination.
The crude protein content in ungerminated amaranth
grain was 15.4%. After 5 hours of steeping the crude
protein content increased to 16.6%. At p< 0.05 there
were no significant differences in protein content
with respect to steeping and germination times. Ruiz
and Bressani [14] reported that the protein content in
ungerminated amaranthus crentus as 14.6%. They
also reported that there was no significant change in
protein content with increase in germination time.
Mbithi-mwikya et al [4] reported that there was a
slight but significant increase in protein content of
fingermillet at each sampling time, from 6.1% in
ungerminated seeds to 7.9% during the 96 hours of
germination. Mbithi-mwikya[4], attributed the
increases in protein content to be due to dry matter
loss particularly through carbohydrates through
respiration causing an apparent increase in other
nutrients such as proteins. Khalil et al [15], also
reported a slight increase in protein content after
germination of soybean and lupin seeds for 72 hours.
Ungerminated amaranth grain had a crude fibre
content of 4.3%. The crude fiber content of amaranth
grain varied with different steeping and germination
time as shown by Table 2. At p<0.05, there were
significant differences in the crude fibre content of
the amaranth grain samples. Ruiz and Bressani [14]
reported that the crude fibre content of amaranth
crentus is 2.2% and that there was no significant
change in crude fibre content of amaranth grain with
change in germination time.
Effect of steeping and germination on some
antinutrients in amaranth grain
Ungerminated amaranth grain had a tannin content of
0.8% CE. When amaranth grain was germinated
tannin content could not be detected. It must have
been reduced to very low levels. Whittaker and
Ologunde [16], reported that the tannin content in
raw amaranth grain is 0.22 mg CE/ 100g. Hemalatha
et al [17] reported that germination significantly
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J. Agric. Food. Tech., 1(6) 101-105, 2011
reduced the tannin content in some food grains such
as green gram, chickpea and fingermillet.
In ungerminated amaranth grain the phytate content
was found to be 7.9 mg per 100g. When the amaranth
grain was germinated, their phytate content could not
be detected. This could mean that the phytates were
all broken down from the inosital hexaphosphate
form. Whittaker and Ologunde [16] reported that
phytate content in raw amaranth cereal is 7.92 mg/g.
Ruiz and Bressani [14] reported the phytic acid
content in amaranth crentus grain as 0.29%. However
with increase in germination time the phytic acid
content decreased and after 72 hours of germination
the phytic acid content could not be detected. Archana
[18] reported that malting with 72 hours of
germination was most effective in reducing the
antinutrient levels of pearl millet grains. Because
germination is mainly a catabolic process that supplies
important nutrients to the growing plant through
hydrolysis of reserve nutrients, reduction in phytic
acid was expected [18]. Since phytic acid may be one
of the factors responsible for reducing mineral
bioavailability its reduction during germination may
enhance the nutritional quality with respect to mineral
bioavailability of amaranth grain.
Ungerminated amaranth grain had an IVPD of 77.6%
on dry weight basis. After steeping for 5 hours and
germinating for 24 hours the IVPD increased by
15.6%. The IVPD varied with various steeping and
germination times as shown by Table 2. Mbithi-
mwikya[4] reported that IVPD increased from 33.9%
in the ungerminated seeds of fingermillet to 55.4% at
96 hours, an increase of 64%. They suggested that
partial solubilization and some proteolysis which
usually occurs during germination could have caused
this. Germination of ingredients increased nutrient
density and invitro protein digestibility [20].
Chauman and Kumar [19] reported that percent
protein digestibility (in vitro) of pearl millet grain
improved following germination at all temperatures.
They reported that the improvement in protein
digestibility during germination may be attributed to
modification and degradation of storage proteins of
the grain. Sprouting causes mobilisation of proteins
with the help of activated proteases, leading to the
formation of polypeptides, oligopeptides and amino
acids. Furthermore hydrolytic reduction of phytates
during germination may also partly account for the
improved protein digestibility of millet sprouts
because phytates are known to inhibit proteases [19].
Conclusion
There was change in the proximate composition of
the amaranth grain with processing. However loss in
dry matter will affect the total nutrients. Therefore
the lesser time for steeping and germination the
better. The antinutrient level are generally lower than
other grains and are reduced to levels they can not be
determined even with minimum processing periods.
REFERENCES
1. Kenya National Bureau of Statistics (KNBS) and
ICF Macro. (2010). Kenya Demographic and
Health Survey 2008-09. Calverton, Maryland.
2. Kenya National Bureau of Statistics Basic Report,
2007. Kenya Integrated Household Budget Survey
(KIHBS) 2005/06. 163, 167.
3. Gibson, R. S., L, Perlas, and Horz, C.,2006.
Improving the Bioavailability of Nutrients in Plant
Foods at the Household level. Proceedings of the
Nutrition Societ.65: 160-168, University Press.
Online Cambridge University.
4. Mbithi-mwikya, S., J. V, Camp. and A
Huyghebaert, 2000. Development of a
Fingermillet based Complementary Food for
children. PhD Thesis. Ghent University. Belgium.
5. A.O.A.C. 1995 “Official Methods of Analysis, 16th
ed. Association of Official Analytical Chemists,
methods Washington.
6. Burns, R. E.,(1963. Methods of Tannin analysis for
forage crop evaluation. Georgia Agricultural
Experiment Station Technical Bulletin 32:1-14.
7. Price, M. L., S.W, Van Scoyoc, and L. G
Butler,1978. A Critical evaluation of the vanillin
reactions as an assay for tannins in Sorghum
grains. J. of Agric. Food Chem. 26: 1214-1218
8. Makokha, O.M., K. R Oniango, and M. S Njoroge,
2002. Malting characteristics of some Sorghum
(Sorghum bicolor) and finger millet (Eleusine
coracona) grain varieties grown in Kenya. PhD
Thesis. Jomo Kenyatta University of Agriculture
and Technology. Kenya.
9. Camire, A. L and M, Clydesdale,1982. Analysis of
Phytic acids in Fooods by HPLC. J Food Sci.47.
576.
10. Mertz, E. T., M. M, Hassen., C Cairns-Whitten, A.
W. Tu and Axtell, J. D, 1984. Pepsin digestibility
of proteins in Sorghums and other major cereals.
Proc. Natl. Acad. Sci. 81:1-2.
11. Wijngaard, H. H., H. M. Ulmer, M. Neumann, and
E. K.Arendt, 2005. The Effect of Steeping Time
on the Final Malt Quality of Buckwheat. J. Inst.
Brew. 111(3), 275–281.
12. Berghofer, E and Schoenlechner, R. (2009).
Pseudocereals overview.
www.sik.se/../Berghofer.pdf/2010
13. Souci, S.W., W. Fachmann, and H. Kraut. (2000).
Food composition and nutrition tables.
Wissenchaft verlags Gmbitt, Sturttgart Raules J,
Nair BM (1993) Content of fat, vitamin and
minerals in quiona (Chemopodium quinoa, wills
seeds. Food Chemistry, 481.131-136.
104
Kanensi et al., 2011
14. Colmenares de Ruiz and R. Bressani, 1990.
Effect of Germination on the Chemical
Composition and Nutritive Value of Amaranth
Grain. Cereal Chemistry 67
15. Khalil, A. A., S. S.Mohammed., F. S Taha, and E.
N.Karslson, 2006. Production of Functional
Protein Hydrolysates from Egyptian breeds of
Soybean and Lupin seeds. African Journal of
Biotechnology Vol.5910), pp.907-916. ISSN1684-
5315, Academic
Journals.http://www.academicjournals.org/AJB.
16. Whittaker, P and M.O. Ologunde, 1990. Study of
Iron Bioavailability in a Native Grain Amaranth
Cereal for Young Children using a rat model.
Cereal Chem.67(5):505-508.
17.Hemalatha, S., K Platel and K, Srinvesank,2007.
Influence of Germination and Fermentation on
Bioaccessibility of Zinc and Iron from Food
Grains European Journal of Clinical Nutrition 342-
348: pg 61. Doi:10.1038/cjn.1602524.
18. Archana, S. S. and A. Kawatra, 1998. Reduction
of Polyphenol and phytic acid content of pearl
millet grains by malting and blanching. Plant
Foods for Human Nutrition 53: 93-98:
19. Kumar, A and B.M Chauhan, 1993. Effects of
Phytic acid on Protein digestibility (in vitro) and
HcL extractablility of minerals in pearl millet
sporuts. Cereal chemistry. 70(5) American
Association of Cereal Chemists, Inc. 504-506.
20. Griffith, L. D., M. E Castell-Perez and M . E,
1998. Effects of blend and processing method on
the nutritional qualities of Weaning Foods made
from select Cererals and Legumes. Cereal Chem.
75:105-112.
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