Supplementation of Sudanese Sorghum Bread (Kissra) with Bambara Groundnut Flour (Vigna subterranea (L.) Verdc.)
Proximate analysis of Bambara groundnut flour and production of Sudanese sorghum
bread (kissra) supplemented with various ratios of Bambara groundnut flour were
conducted. Bambara groundnut flour was used in supplementation of Sudanese baked
product sorghum bread (kissra), in the ratios of 10, 20 and 30%. The pH values
of Bambara groundnut flour supplemented doughs were dropped. The titrable
acidity and total soluble solids were increased as a result of fermentation
process. The most significant effect of kissra supplementation was the increases
in protein content from 12.20±0.02% for the control sorghum bread kissra
to about 13.38±0.02, 13.76±0.02 and 15.54±0.04% for kissra
supplemented with 10, 20 and 30% of Bambara groundnut flour, respectively. The
contents of crude fiber and ash of supplemented sorghum kissra were also increased.
The replacement ratios of Bambara groundnut flour also resulted in a concomitant
increase in the in vitro protein digestibility of kissra breads. The
sensory evaluation revealed that the supplemented sorghum kissra was accepted
by the panelists up to 10% of Bambara groundnut flour supplementation. The overall
acceptance level of the different samples decreased with the additional increases
of Bambara groundnuts flour supplementation. In view of the findings of this
study, it is recommended that, future studies focus on the utilization of Bambara
groundnuts flour on other Sudanese traditional foods such as thin and thick
January 16, 2012; Accepted: April 09, 2012;
Published: June 21, 2012
Kissra is the staple Sudanese diet. It is a morsel or piece of bread prepared
from fermented sorghum flour (Sulieman et al., 2003).
The nutritive value of kissra is basically a discussion of the nutritive value
of sorghum or millet; it was found that in Gezira and Managil areas, cereals
provided 80% of the protein and together with sugar 84.4% of calories in the
diet (Dirar, 1993). The word kissra is Arabic word (El-Tayeb,
1964) and together with the word Aceda, has been mentioned in the early
Arabic books (Al-Jahiz, 1981). Literally, the word kissra
is a morsel or a piece of bread (Tothill, 1948). Two
kinds of kissra can be described based on the method of spreading the dough
during baking, kissrat-kass and kissrat-gergriba. In the baking of former, the
batter is transferred with kass and poured directly into centre of the hot plate
used for baking. The empty kass is then held by the edge in an upright position
and the batter spread with the bottom of the gourd by moving the container in
whirl pool motion in progressively widening circles until the whole batter has
been flattened out into a rippled, circular sheet (Dirar,
Bambara groundnut (Voandzeia subterranea) is a tropical food crop in
Sudan and other tropical areas (Yagoub and Abdalla, 2007).
Bambara groundnut was once said to be the third most important grain legume
after groundnut (Arachis hypogaea L.) and cowpea (Vigna unguiculata
(L.) Walp) in Sub-Saharan African (Aremu et al., 2006a).
In Sudan, Bambara groundnuts is grown in the rainfed areas of Darfur, Kordofan,
Gadarif and Blue Nile regions by the traditional farmers both of male and female
and consumed as a salt-boiled snack food beside maize and cowpea. The flours
of Bambara groundnuts seeds and pearl millet grains are blended and used to
make the traditional thick and thin porridges locally known as Madida and Nesha,
respectively with addition of slight amounts of salt and sugar especially in
western Sudan. Bambara groundnuts can be cultivated up to 1600 m above sea level.
An average day temperature of 20 to 28°C is ideal for the crop (Chittaranjan,
2007). A growth plant period of 110 to 150 day is required for the crop
to develop, depending upon environment and landrace. Bambara beans will grow
on any well-drained soil but light, sandy; loams with a pH of 5.0 to 6.5 are
most suitable. The crop does well on poor soil which is low in nutrients (Chittaranjan,
2007). Bambara groundnut is an annual crop, which resembles groundnut (Arachis
hypogaea) in both cultivation and habitat. It is one of the five most important
protein sources for many Africans (Chittaranjan, 2007).
The reported proximate chemical composition of Bambara groundnut seeds is water
(14.7), ash (3.24), crude protein (22.2), fat (6.6), cellulose (4.4) and carbohydrates
(63.56%) (Chittaranjan, 2007).
Sorghum (Sorghum bicolor L. Moench) plays an important role as a major
staple crop of the arid and semi-arid tropics. Sorghum is mainly produced by
small holder farmers under rain-fed conditions that have been predicted to be
adversely affected by climate change (Abdulai et al.,
2012). Sorghum bicolor is the most extensively cultivated in the
drier Northern Guinea, Sudan Savannah and Greenland of Africa, Plains of India
and the Great plains of United State of America. It is known to be the fourth
most important cereal crop after wheat, rice and maize and is a dietary staple
of millions of the worlds poorest people in the Sahelian zone of Africa,
Middle East, India and China (Adetuyi et al., 2007).
S. bicolor the fifth most important cereal crop after wheat, rice, maize
and barley in terms of production. Total world annual sorghum production is
about 60 million tons from cultivated area of 46 million ha (Dicko
et al., 2006). Fifty percent of sorghum is grown directly for human
consumption. It is one of the major staple foods in Africa, Middle East and
Asia. Sorghum is an important animal feed used in countries like United State,
Mexico, South America and Argentina. Good quality sorghum is available with
nutritional feeding value that is equivalent to that of corn (Adebiyi
et al., 2005). The grain is higher in protein and lower in fat content
than corn (Yohe, 2002). This study was aimed to improve
the nutritive value of sorghum kissra by the supplementation with various levels
of Bambara groundnuts seeds flour.
MATERIALS AND METHODS
Materials: Bambara groundnut seeds were collected from a farm located at
Um-Gouna village, Southern Darfur State, Sudan, during the harvesting period
in 2008. The seeds were carefully cleaned and freed from foreign materials.
Sorghum flour (Tabat variety) were purchased from the local market in Wad-Medani;
Gezira State, Sudan.
Preparation of Bambara groundnuts flour: The seeds were washed, sun
dried and milled into fine powder using a Wiley mill (Rekord A. Gbr, Jehmlich
GmbH, Nossen, Germany), then the flour was passed through 60 mm mesh sieve (British
standard). The flour was bottled and kept at room temperature (31°C) for
Chemical analysis: Proximate analysis of flours of Bambara groundnut
and sorghum; control sorghum kissra and sorghum kissra supplemented various
ratios of Bambara groundnut flour were conducted for the contents of moisture,
ash and crude fat according to the AOAC (2005). Crude
protein was calculated as Nx6.25 according to the AOAC (1990).
Crude fiber was determined by acid/alkali digestion method according to the
AOCS (1985). Total carbohydrate content was calculated
by subtracting the previous components from 100.
In vitro protein digestibility: In vitro protein digestibilities
of the different types of kissra were determined according to the three-enzyme
method which was described by Hsu et al. (1977)
and Satterlee et al. (1979) in which a multi-enzyme
solution of (1.6 mg trypsin, 3.1 mg chymotrypsin and 1.3 mg peptidase mL-1)
was used in the determination.
Preparation of the control and supplemented kissra: In the control sample,
1000 g of sorghum flour were mixed with 2 L water in a round earthenware container
(Khumara) (250 g) of previously fermented dough were added to the mixture to
act as a starter culture. In supplemented samples, 10, 20 and 30% of Bambara
groundnut flour were used to supplement sorghum flour in such a way that the
dough contained a total of 1000 g of flours of sorghum and Bambara groundnut.
Two liters of water and 250 g of starter culture were then added. All the samples
were allowed to ferment for 18 h at 32°C (Sulieman et
Dough analysis: All of the dough samples were analyzed for pH, Total
Titrable Acidity (TTA) and Total Soluble Solids (TSS) before and after fermentation
period. The pH was determined using (Hanna, pH 211) Microprocessor pH meter).
Total titrable acidity was determined by titration against 0.1 N KOH according
to the AOAC (1990). The total soluble solids were determined
using (Atago, N1, brix 0~32, Japan) refractometer as described by Pomeranz
and Meloan (1987).
Baking of kissra: The kissra sheets were baked traditionally as described
by Dirar (1993) method with some modification. A steel
plate (Saj) was heated to about 155°C. A small amount of fermented dough
(85 g) was spread on the hot plate into a thin sheet which was peeled off the
plate after 12 sec baking. The produced kissra sheets were stacked one over
the other and were ready for further analysis.
Sensory evaluation: A panel of twenty members composed of adults male
and female was used to judge the quality of the different types of kissra supplemented
with various ratios of Bambara groundnut flour, as well as the control kissra.
The panelists were asked to evaluate each sample for appearance, texture, colour,
flavour and overall acceptability using a 9 point hedonic scale from 1 to 9
as follows: 1: Extremely bad; 2: Very bad; 3: Bad; 4: Fairly bad; 5: Satisfactory;
6: Fairly good; 7: Good; 8: Very good; 9: Excellent as described by Iwe
(2002). The order of presentation of the various samples was randomized
and given codes before being tested by the panelists.
Statistical analysis: Data of organoleptic evaluation of the different
types of sorghum kissra were subjected to the analysis of variance procedure
and the means were separated at 0.05 levels according to the method described
by Snedecor and Cochran (1980).
RESULTS AND DISCUSSIONS
Proximate analysis of flours of Bambara groundnut and sorghum showed that the
contents of protein, ash, fat and crude fiber of the Bambara groundnut are higher
than of sorghum; while the contents of moisture and carbohydrate are lower as
presented in Table 1.
The moisture content of Bambara groundnut flour (4.0±0.03%) is similar
to that reported by Doku and Karikari (1971) and Duke
(1981), lower than that reported by Omoikhoji et
al. (2006) and higher than that found by Aremu et
al. (2006b) who reported values of (3.0-4.0, 10.12 and 2.07%), respectively.
The low moisture content will afford a long shelf-life for the legume flours
(Aremu et al., 2006b). The variation in moisture
content could be attributed to the environmental conditions. The estimated protein
content (29.17±0.05%) is higher than the values of (22.10, 11.56, 19.61%)
reported by Yagoub and Abdalla (2007), Aremu
et al. (2006a) and Omoikhoji et al. (2006),
respectively. The ash contents are 4.17±0.01%. The data is higher than
the values of 3.76, 3.41% that reported by Yagoub and Abdalla
(2007) and Omoikhoji et al. (2006), respectively
and lower than the value of 4.28% reported by Aremu et
al. (2006a). The variations in the ash contents of Bambara groundnut
could be due to the agronomic practices and the variety or the soil type. Generally,
the end products were made from the low ash content sample were brighter and
more uniform in colour than those made from high ash content (Eltayeb,
2005). The fat contents 5.20±0.03% are higher than 5.0% reported
by Yagoub and Abdalla (2007) and lower than that of
Omoikhoji et al. (2006) and Aremu
et al. (2006a), who reported the values of 6.45, 6.72%, respectively.
The variations in fat contents may probably be due to the genetic types and
the environmental conditions. The estimated value of crude fiber (4.69±0.04%)
is higher than that of Aremu et al. (2006a), Yagoub
and Abdalla (2007) and Omoikhoji et al. (2006)
who found the values of 2.07, 3.72, 4.45%, respectively. The carbohydrates content
(56.77±0.03%) is higher than the value of 54.95% reported by Omoikhoji
et al. (2006) and lower than the values of Yagoub
and Abdalla (2007) and Aremu et al. (2006a)
who reported the values 65.0, 73.30%, respectively. The in vitro protein
digestibility (79.24±0.05%) is in agreement with (78.75%) that reported
by Yagoub and Abdalla (2007). However, the Bambara groundnut
seeds are also reported to contain trypsin and chymotrypsin inhibitors, which
act as anti-nutritional factors. Roasting the Bambara groundnut helps greatly
in reducing the trypsin inhibitors and subsequently improves their nutritional
value (Chittaranjan, 2007).
The sorghum contents of moisture, fat and fiber (7.5±0.04, 3.64±0.06,
2.00±0.05%) are lower than the values 9.8, 3.90, 2.5% and 12, 3.7, 2.2%,
that reported by Mustafa (2002) and Leung
et al. (1972), respectively. However, the contents of protein, ash
and carbohydrate 11.03±0.04, 1.73±0.04 and 81.60±0.02%
are higher than the values 10, 1.55, 72.25% and 10, 1.5, 72.7% that determined
by Mustafa (2002) and Leung et
al. (1972), respectively.
||Chemical composition and in-vitro protein digestibility
of flours of Bambara groundnut seeds and sorghum grains, on dry weight-basis
|ND: Not determined
The pH, total titrable acidity and total soluble solids contents of control,
fermented and non-fermented dough supplemented with different ratios of Bambara
groundnut flour are presented in Table 2.
The pH values of all the fermented samples are slightly lower than that of
non-fermented samples. The drop in pH values is accompanied with an increase
in titrable acidity. El-Tinaysp et al. (1985)
reported a drop of control dough from 5.28 to 3.76 at the end of fermentation.
Au and Fields (1981) reported that a pH drop from 6.7
to 3.8 during the first 2 days of sorghum fermentation and gradually leveled
off on the 3rd and 4th day. They also reported a concomitant rise in titrable
The contents of total titrable acidity are increased. The increases in total
titrable acidity resulted in production of very thin kissra sheets; an explanation
of this was given by Novellie (1982) who stated that
the acid produced by fermentation softens the protein matrix so that the fermented
dough becomes more coherent and can easily spread out into very thin sheet which
can be peeled off the plate easily. The estimated total soluble solids are higher
in supplemented dough as a result of Bambara groundnut flour supplementation
process. However, the total soluble solids contents of fermented dough are lower
than that of non-fermented dough.
As shown in Table 3, the moisture contents of supplemented
sorghum breads kissra (55.0±0.07, 58.15±0.04, 60.0±0.04%)
are increased as a result of Bambara groundnut flour supplementation. The moisture
contents are higher than the range of 52-53% reported by El-Tinay
et al. (1979) and lower than the range of 70.2-73.6% reported by
Muller (1981). The most significant effect of Bambara
groundnut flour supplementation is the increases in protein contents (13.38±0.02,
13.76±0.02, 15.54±0.04%). The protein contents are in agreement
with the range of 9.5-15.4% that reported by Muller (1981)
and higher than the value of 12.5% that determined by El-Mahdi
(1985) and El-Tinaysp et al. (1985).
||pH, total titrable acidity (TTA) and total soluble solids
(TSS) contents of control, fermented (F) and non-fermented (NF) dough supplemented
with different ratios of Bambara groundnut flour
|BGF: Bambara groundnuts flour
||Chemical composition and in vitro protein digestibility
of control kissra and kissra supplemented with various ratios of Bambara
|BGF: Bambara groundnuts flour
||The mean scores for sensory attributes of control and sorghum
bread kissra supplemented with different ratios of Bambara groundnut flour
|Means based on 9 points scale (9: Excellent, 1: Extremely
bad), BGF: Bambara groundnut flour, a, bMeans within the same
column having the same letters are not significantly different according
to the Duncan's multiple range tests
The protein contents are also higher than 12.52% of a weaning food formulated
from un-germinated sorghum and steamed cooked cowpea that reported by Elemo
et al. (2011). The ash contents (1.72±0.01, 1.98±0.03,
2.23±0.02%) increases as a result of additional increase of Bambara groundnut
flour. The ash contents are higher than of Elemo et al.
(2011) who reported 1.6% as a weaning food ash content. The fat contents
(3.53±0.02, 3.70±0.01, 3.86±0.02%) are lower than 5.1%
reported by Eggum et al. (1983) and higher than
the range of (0.81-1.54%) that reported by Muller (1981).
The fiber contents (3.50±0.05, 3.64±0.03, 3.75±0.03%) are
higher than (2.58%) that reported by El-Mahdi (1985) and
El-Tinaysp et al. (1985) and lower than (3.8%)
determined by El-Tinay et al. (1979). The carbohydrate
content of control sample (79.59%) is higher than the contents of supplemented
sorghum kissra (77.87±0.05, 76.92±0.03, 74.62±0.04%). The
carbohydrate contents are lower than (80, 82.6%) reported by Sukkar
et al. (1975) and Boutros (1977), respectively.
The increase in the replacement levels of Bambara groundnut flour led to the
increase in the in vitro protein digestibility of sorghum bread kissra
from 71.57±0.02% for the control kissra to the 74.90±0.05, 78.23±0.02
and 81.56±0.04% of supplemented kissra. The in vitro protein digestibility
is in agreement within the range of 65-86% that reported by Axtell
et al. (1981).
The mean scores for sensory attributes of the control sorghum kissra and sorghum
kissra supplemented with different ratios of Bambara groundnut flour are presented
in Table 4. The sensory evaluation indicated that there were
significant differences as regarded to appearance and colour and there were
no significant differences as regard to flavour and overall acceptability. The
supplemented kissra was accepted by the panelists at all levels of Bambara groundnut
flour supplementation. However, the sorghum kissra supplemented with 10% of
Bambara groundnut flour was rated by the panelists as good as control sorghum
bread kissra. The overall acceptance level of the different samples decreased
with the additional increase of Bambara groundnut flour.
It could be concluded that, the study succeeded to develop in the development
of new product of sorghum bread kissra of high nutritive value through the utilization
of the Darfurian neglected crop (Bambara groundnut seeds flour). The most significant
effect of sorghum kissra supplementation is the improvement in quantities of
protein and in vitro protein digestibility. Kissra supplemented with
10% of Bambara groundnut flour is similar to the control sample in all properties
of the sensory attributes.
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