PHYSICOCHEMICAL PROPERTIES OF MAIZE-TILAPIA FLOUR BLENDS
O.S. FASASI1, I.A. ADEYEMI2 and O.A. FAGBENRO3
1
Department of Food Science and Technology
Federal University of Technology, Akure, Nigeria.
2
Department of Food Science and Engineering
Ladoke Akintola University of Technology, Ogbomosho, Nigeria.
3
Department of Fisheries and Wildlife
Federal University of Technology, Akure, Nigeria.
ABSTRACT
Blends from fermented maize flour (MF), unfermented tilapia flour (UF) and fermented
tilapia flour (FF) were prepared at ratios 6.25:1 (M:UF1), 8.87:1 (M:UF2), 6.25:1 (M:FF3),
and 9.30:1 (M:FF4); and both the proximate composition and physicochemical properties
of the blends were determined. The maize-tilapia flour blends contained 5.90-9.55%
moisture, 14.09-16.00% crude protein, 6.20-6.40% crude fat, 2.25-2.30% ash, and 65.9169.83% carbohydrate; compared to those of MF which contained 11.69% moisture,
7.63% crude protein, 4.00% crude fat, 1.62% ash, and 86.74% carbohydrate. The water
absorption capacities (WAC) of maize–tilapia blends range was 253.3-300.0%, oil
absorption capacities (OAC) range was 150.0-246.7%, least gelation concentrations were
4.0-8.0%, bulk densities range was 0.355-0.610g/ml. Solubility and swelling power of the
blends increased with the inclusion of tilapia flour, while solubility and swelling power
increased with increase in temperature. The WAC of the blends therefore gave it an
advantage of being used as a thickener in liquid and semi-liquid foods, and may serve as
good binder or provide consistency in food preparations such as semi-solid beverages.
Key words: Physicochemical properties, maize-tilapia flour, .
INTRODUCTION
Cereals root and tuber crops are the staple food of people in the tropics, and provide about
75% of their total caloric intake and 67% of their total protein intake. They are foods with
low nutritional value as they are not adequate sources of micro and macro nutrients
(Brown, 1991). Efforts to improve the nutritional value of these staples have been based
on fortification with legumes to boost the deficient amino acids (Bressani & Elias, 1983;
Salami, 1988). The protein quality is synergistically improved in cereal-legume blends
and is of variable organoleptic properties and poor digestibility; which is attributed to the
low solubility of plant proteins (Okeiyi & Futrell, 1983).
Functional properties (solubility, foamability, gelation and emulsification properties) are
the intrinsic physicochemical characteristics which may affect the behaviour of food
systems during processing and storage. Adequate knowledge of these physicochemical
properties indicates the usefulness and acceptability for industrial and consumption
purpose. Previous studies on physicochemical properties have focused on flours of
protein-rich seeds (Sathe & Salunkhe, 1981a, 1981b; Akobundu et al., 1982; Ige et al.,
1
1984; Oshodi & Ekperigin, 1989; Fagbemi & Oshodi, 1991; Oshodi & Adelakun, 1993;
Oshodi et al., 1995; Ogungbenle et al., 2002).
The essential amino acids limiting in cereals, roots and tuber crops are present in fish; a
mix containing fish and these foodstuffs are therefore complementary. There is limited
information on the physicochemical properties of blends of cereals and proteins
especially animal protein (fish). Tilapias are widely cultivated fish species in Africa
(Popma & Masser,1999). They are often discarded in fish farms due to their tendency to
overpopulate ponds, because of their high fecundity which results in stunted growth, and
failure to command good market price. There is however a need to use the excess and
underutilized tilapias for the development of highly digestible and proteinous cereal mix.
This study is aimed at investigating the physicochemical properties of maize-tilapia flour
blends in order to enhance its commercial utilization.
MATERIALS AND METHODS
Source of Raw Materials
Nile tilapia (Oreochromis niloticus) samples were obtained from a government fish farm
in Ibadan, Nigeria. The fish was transported in frozen blocks to Food Science and
Technology laboratory of the Federal University of Technology, Akure, Nigeria. Fresh
tilapias were descaled, degutted and washed in clean water; they were steamed for 15
minutes and minced. The minced tilapia was divided into two parts: one portion was
oven-dried at 60oC, milled and sieved with a 200 mm mesh sieve to obtain unfermented
fish flour (UF). The second portion was subjected to natural fermentation by spreading on
a tray for 24 hours at room temperature (30±2oC). Samples were oven-dried at 60oC and
milled to obtain the fermented fish flour (FF). Yellow maize grains were purchased from
Oja-Oba in Akure, Nigeria; and processed into “Ogi” using an improved method with
greater protein recovery (Akingbala et al., 1987). The fresh “Ogi” was oven-dried at 60oC
and milled into flour, and sieved in 200 mm mesh to obtain the fermented maize flour
(M). The resultant flour samples - M, UF and FF were packaged in air-tight polythene
sachets and stored at 4oC until used.
Blend Formulation
Flours obtained were subjected to proximate analysis and results obtained were subjected
to QuatroPro 1997 statistical tool in order to obtain blend ratios (Table 1) similar to a
target reference diet “Cerelac” - a commercial cereal-based weaning product in Nigeria
(Fasasi et al., 2005). Maize-tilapia blends obtained were packaged in air-tight polythene
sachets and stored at 4oC prior to further analyses.
Table 1. Blend ratios.
Blends
M:UF1
M:UF2
M:FF3
M:FF4
MF
6.25
8.87
6.25
9.30
UF
1
1
-
FF
1
1
MF-Maize flour; UF- Unfermented fish flour; FF- Fermented fish flour.
2
Determination of the physicochemical properties
Proximate analysis of Maize-tilapia blends
Moisture, crude protein (g N x 6.25), fat, Ash were determined in triplicate by standard
procedures (AOAC, 1990). Total carbohydrate was calculated by difference.
Water absorption capacity
The procedure of Sathe et al. (1982a) was used. 10 ml of water added to 1.0 g of each
blend samples, the suspension was then stirred using magnetic stirrer for 5 min. the
suspension was transferred into centrifuge tubes and centrifuged at 3,500 rpm for 30 min.
the supernatant obtained was measured using a 10 ml measuring cylinder. The density of
the water was assumed to be 1g/ml. The water absorbed was calculated as the difference
between the initial water used and the volume of the supernatant obtain after centrifuging.
The result was expressed as a percentage of water absorbed by the blends on %g/g basis.
Oil Absorption Capacity (OAC)
The procedure of Sathe et al. (1982a) was used as described above. Instead of water used,
refined soybean oil with density of 0.92g/ml was used. The oil and the flour blends (1g
from blends in 10 ml oil) were mixed using a magnetic stirrer at 1,000 rpm for 5 min and
then centrifuged at 3,500 rpm for 30 minutes, the amount of oil separated as supernatant
was measured using 10 ml cylinder. The difference in volume was taken as the oil
absorbed by the samples. The oil absorbed was expressed as %g/g of oil absorbed.
Bulk Density (Packed Bulk Density and Loose Bulk Density)
The procedure of Akpapunam & Markakis (1981) was used. A specified quantity of the
blends was put into a weighed 5ml measuring cylinder (W1). For packed bulk density
(PBD), it was gently tapped to eliminate air spaces between the flour blends in the
cylinder and the volume was noted as the volume of the sample used. The new mass of
the sample and the cylinder was recorded (W2). The bulk density was expressed as: BD
=W2-W1. For loose bulk density (LBD) space was not eliminated by trapping.
Least Gelation Concentration (LGC)
The Least Gelation Concentration (LGC) of the flour blends was determined using the
modified method of Coffman & Garcia (1977). Sample suspensions of 2%, 4%, 6%, 8%,
12%, 14%, 16%, 18% and 20% (m/v) were prepared in 10 ml distilled water in test tubes.
The tubes containing the suspensions were then heated for 1 hour in a gentle boiling
water bath, after which the tubes were cooled rapidly in water at 40 oC for 2 hours. Each
tube was then inverted one after the other. The LGC was taken as the concentration when
the sample from the inverted test tube did not fall or slip.
Swelling capacity and Solubility
The method described by Leach et al. (1959) was used with slight modifications. Flour
blends (1 g) was weighed and transferred into a clean dry test tube and weighed (W1).
The mix was then dispersed in 50cm3 of distilled water using a magnetic stirrer. The
resulting slurry was heated at desired temperatures – 40oC, 50oC, 60oC, 70oC, 80oC, 90oC
for 30 minutes in a thermo stated water bath. The mixture was cooled to room
temperature and centrifuged at 2,200 rpm for 15 minutes. 5 ml of aliquot of the
3
supernatant was dried to a constant weight at 120oC. The residue obtained after drying
represented the amount of starch solubilized in water. Solubility was calculated as per
100g of starch on dry basis. The residue obtained after centrifugation with the water it
retained was transferred to the clean dried test earlier and re-weighed (W2).
Swelling of starch
=
W2 – W1 x 100
Weight of flour
RESULTS AND DISCUSSION
Blends containing unfermented tilapia (UF) had higher protein content maize flour (MF)
(Table 2) (P<0.05). Crude protein content ranged from 14.09% (M:FF4) to 16.00%
(M:UF1). There was a substantial increase in protein content of MF after blending with
UF and FF. Fat content ranged from 6.20% in M:FF4 to 6.40% in M:UF2, and were above
the minimum FAO/WHO pattern for weaning foods (Mitzner et al.,1984).
Table 2. Proximate composition (%) of Maize –Tilapia blends
Components
Moisture
Crude protein
Fat
Ash
Carbohydrate
MF
11.69a±0.03
7.63d±0.02
4.00c±0.04
1.62b±0.02
86.74a±0.05
M:UF1
9.55b±0.02
16.0a±0.03
6.24b±0.00
2.30a±0.05
65.91b±0.01
M:UF2
5.90d±0.01
15.72b±0.01
6.40a±0.03
2.25a±0.01
69.73a±0.00
M:FF3
5.99d±0.05
15.68b±0.02
6.38a±0.01
2.26a±0.04
69.78a±0.01
M:FF4
7.61c±0.03
14.09c±0.01
6.20b±0.02
2.27a±0.01
69.83a±0.02
Mean ±SD of at least three determinations.
Values in a row denoted by different superscripts differ significantly.
The water absorption capacity (WAC) of maize flour the blends (Table 3) showed that
M:FF3 had the highest value and M:UF2 had the lowest value. This implies that the
addition of fermented tilapia to maize flour increased the water absorption capacity. SefaDedeh (2002) similarly reported that water absorption capacity in the product increased
with the addition of cowpea. The values obtained are higher than the values reported for
taro flours - red 180%, white 166%, nive 150% (Tagodoe & Nip, 1994), soybean flour,
130% (Lin et al.,1974), fluted pumpkin seed flour, 85% (Fagbemi & Oshodi,1991), sweet
potatoes flour, red 24%, white 26% (Osundahunsi et al., 2003). The extent of protein
hydration correlates strongly with the content of polar residues as well as the interaction
between water molecules and hydrophilic groups which occurs via hydrogen bonding.
The higher protein content of the blends containing fermented tilapia might be
responsible for high hydrogen bonding and high electrostatic repulsion, both conditions
facilitating binding and entrapment of water (Altchul & Wilcke, 1985). Hence, WAC of
the blends gave it an advantage of being used as a thickener in liquid and semi-liquids
foods since the flours has the ability to absorb water and swell for improved consistency
in food.
Table 3. Physicochemical properties of the samples
Samples
MF
M:UF1
M:UF2
M:FF3
M:FF4
WAC
(%)
271.70.6
260.00.1
253.30.3
3000.7
266.70.7
OAC
(%)
176 .00.5
230.00.3
150.00.8
153.30.3
246.70.9
Bulk Density (g/ml)
Loose
packed
0.4681.7E-03 0.5705.8E-03
0.3726.5E-03 0.5131.86E-03
0.3843.1E-03 0.5805.8E-03
0.3552.9E-03 0.5252.9E-03
0.3834.4E-03 0.6105.8E-03
Mean±SE of at least three determinations
4
Least Gelation
Concentration (%)
10 .00.0
8.00.4
6.00.3
6.00.4
4.00.3
Oil absorption capacity (OAC) of blends ranged between 150-246% with blends
containing fermented tilapia (M:FF4) having the highest OAC. This value is higher than
OAC of taro flours (190%, Tagodoe & Nip, 1994), sweet potatoes flour (10-12%,
Osundahunsi et al., 2003), lupin seed flour, 167% (Sathe et al., 1982b). The high OAC of
the blends containing fermented tilapia may be due to increase in protein in M:FF4 which
enhanced hydrophobicity by exposing more a polar amino acid to the fat (Chau &
Cheung,1998). Protein denaturation and dissociation may occur during tilapia
fermentation which exposes the apolar amino acid of the fish proteins thus enhancing
hydrophobicity of protein (Hutton & Campbell, 1981; Vausinas & Nakai, 1983). OAC is
the ability of the flour blend protein to physically bind fat by capillary attraction and it is
of great importance since fat acts as flavor retainer and increase the mouth feel of foods
(Kinsella, 1976). It is also an important factor in preparation of meat extenders and in
ground meat formulation such as sausages (del Rosario & Flores, 1981). Blends of maize
and fermented tilapia (M:FF4) may be of good use for this purpose.
The loose bulk densities (LBD) of maize-tilapia flour blends ranged from 0.355-0.384
g/ml while the packed bulk densities (PBD) ranged from 0.513 – 0.610 g/ml. The LBD
and PBD of MF were 0.468 and 0.570, respectively. Tilapia incorporation had no
significant effect on the bulk densities of the flour blends. Contrastingly, Edema et al.
(2005) reported a decrease in the bulk density of maize with increasing soy
supplementation. The differences could be attributed to the incorporated materials (tilapia
vs. soy) and supplementation level (20% soy). The difference between the loose and the
bulk densities of flour blends was slight, indicating that the volume of the blends in a
package will not decrease excessively during storage or distribution. The bulk densities of
blends are lower compared to durum wheat blends (0.80-0.82 g/ml) (Amajeet et al., 1993)
thereby making the blend suitable for the formulation of high nutrient density weaning
food (Desikachar, 1980).
The lower the least Gelation Concentration (LGC) the better the gelling ability of the
flour. The LGC of maize-tilapia flour blend ranged from 4% to 6%, when compared with
MF which has an LGC of 10%, the maize-tilapia flour blends had better gelling ability.
The LGC of the maize-tilapia flour blends is less than value reported for Great Northern
bean (10%) (Sathe & Salunkhe, 1981), pigeon pea flour (12%) (Oshodi & Ekperigin,
1989), lupin seed flour (14%) (Sathe et al., 1982) and cowpea (16%) (Abbey & Ibeh,
1988). The variations in LGC could be attributed to the relative ratios of different
constituent proteins, carbohydrates and lipids in the flour samples. Sathe et al. (1982a)
reported that interactions between such components play a significant role in the
functional properties. Maize-tilapia flour blends, especially M:FF4, may serve as a good
binder or provide consistency in food preparations such as semi-solid beverages e.g.
Kunun zaki (Adeyemi & Umar, 1994).
Effect of Temperature on Solubility
Fig. 1 shows the effect of temperature on the solubility of the maize-tilapia flour blends.
Solubility of the maize-tilapia blends increased with increase in temperature. As can be
seen in Fig. 1, the relationship describing the dependent variable (Y) and the independent
variable (X) was quadratic in nature, the regression equations for each of the samples are
shown (Table 4) Schoch (1964) reported that the degree of swelling and amount of
soluble components depends on the type and species of starch in the flour samples.
5
According to (Hoover & Martin, 1991; Hoover & Maunal, 1996) that, increase in
temperature allowed amylose (water soluble fraction) molecules located in the bulk
amorphous regions to interact with the branched segment of amylopectin (water-insoluble
fraction) in the crystalline regions. This implies that high temperature weakens the starch
granules of flour leading to improved solubility, the incorporation or addition of tilapia
flour to maize increased the solubility of maize-tilapia flour compared to MF.
SOLUBILITY (%)
25
20
MF
M:UF1
M:UF2
M:FF3
M:FF4
15
10
5
0
0
20
40
60
80
100
TEMP.0C
Fig 1. Effect of temperature on solubility of maize-tilapia blends.
Table 4. Regression equations and R2 values for solubility of samples at different
temperatures.
Samples
MF
M:UF1
M:UF2
M:FF3
M:FF4
Equation
Y = 0.0058 X2 -0.4813X +13.671
Y= 0.0085X2- 0.7167X +19.447
Y = 0.0038X2 -0.1824X+5.5703
Y=0.0085X2-0.7167X+19.447
Y=0.0053X2-0.4298X+13.927
R2
0.9904
0.9772
0.9464
0.9772
0.9405
Effect of Temperature on Swelling Power
The swelling power of the maize-tilapia flour blends increased with increase in
temperature (Fig. 2), similarly reported by Adebowale et al. (2005) for red sorghum flour.
As shown in Fig. 2, the relationship describing the dependent variable (Y) and the
independent variable (X) was quadratic in nature, the regression equations for each of the
samples are shown in Table 5. Maize contains starches which occur in granules, and the
outer membranes of the granules broken during the milling, swell in low temperature
water (40oC and 50oC) to form gel. Remarkable increase in swelling power was observed
between 60oC and 90oC, similarly observed on some legume starches (Hoover & Sosulki,
1991; Wankhede & Ramteke, 1982). This implies that 60oC is the gelatinization
temperature of maize-tilapia flour blends. The swelling pattern of the flour suggests the
level of crystalline packing of the starch granules in the blends. An increase in entropy
offset the hydrogen bonding in the crystalline regions, thereby increasing the swelling
power (Billiadaris, 1982).
6
18
16
MF
M:UF1
M:UF2
M:FF3
M:FF4
14
Swelling Power (%)
12
10
8
6
4
2
0
0
10
20
30
40
50
60
70
80
90
Temp 0C
Fig 2. Effect of temperature on the swelling power of maize-tilapia blends
Table 5. Regression equations and R2 values for swelling power of samples at different
temperatures.
Samples
MF
M:UF1
M:UF2
M:FF3
M:FF4
Equation
Y= -0.0019X2+0.4689X-10.534
Y=-0.0016X2+0.4626X-12.543
Y=-0.0033X2+0.7063X-20.171
Y=0.005X2+0.229X-7.840
Y=-0.0017X2+0.4817X-14.749
R2
0.9526
0.9509
0.9903
0.9313
0.9193
CONCLUSION
The functional properties of maize flour could be enhanced through the addition of tilapia
flour (unfermented and fermented). Increase in water and oil absorption capacities
occurred, the maize-tilapia blends had better gelling ability than maize flour (MF). The
WAC of the blends therefore gave it an advantage of being used as a thickener in liquid
and semi-liquids foods since the flours were able to absorb water and swell for improved
consistency in food. The bulk density of the blends offer it a packaging advantage and
suitable in the preparation of high nutrient density weaning food. Maize-tilapia flour
blends may serve as good binder or provide consistency in food preparations.
REFERENCES
AOAC (1990). Methods of analysis of the Association of Official Analytical Chemists.
15th edition. Washington DC. USA.
Abbey, B.W. & Ibeh, G.O.(1988) Functional properties of raw and eat processed cowpea
(Vigna unguiculata),Walp) flour. Journal of Food Science 53: 1775-1777.
7
Adebowale, K.O., Olu-Owolabi, B.I., Olayinka, O.O. & Olayide, O.S.(2005) Effect of
heat moist treatment and annealing on the physicochemical properties of red sorghum.
African Journal of Biotechnology 4(9): 928-933.
Adeyemi, I.A. & Umer, S.(1994) Effect of method of manufacture on quality
characteristics of Kunun zaki, a millet-based beverage. Nigerian Food Journal 12: 944947.
Akingbala, J.O., Onochie, E.U., Adeyemi, I.A. & Oguntimein, G.B.(1987) Steeping of
whole and dry milled maize kernels in Ogi preparation. Journal of Food Processing and
Preservation 11: 1-11.
Akobundu, E.N.T., Cherry, J.P. & Simmons, J.G.(1982) Chemical, functional and
nutritional properties of Egusi (Colocynthis citrullus L) seed protein products. Journal of
Food Science 47: 149-497
Akpapunam, M.A. & Markakis, P.(1981) Physicochemical and nutritional aspects of
cowpea flour. Journal of Food Science 46: 972-973.
Altschul, A.M. & Wilcke, A.L.(1985) New protein food. Food Science and Technology,
Orlando, FL. Academic Press.
Amarjeet, K., Bhupendar, S. & Sidhu, J.S.(1993) Studies on bread and durum wheat
blends. Chem. Mikrobiol. Technol. Lebensm 15: 35-40.
Billiadris, C.G.(1982) Physical characteristics, enzymatic digestibility and structure of
chemical modified smooth pea and waxy maize starches. Journal of Agricultural Food
Chemistry 30: 925-930.
Bressani, R. & Elias, E.(1983) Guidelines for the development of processed and packaged
weaning foods. Food Nutrition Bulletin 5: 32-36
Brown, K.H.(1991) The importance of dietary quality versus quantity for weanlings in the
developed countries, a framework of discussion. Food Nutrition Bulletin 13: 86-93.
Chau, C.F. & Cheung, P.C.K.(1998) Functional properties of flours prepared from three
Chinese indigenous legume seed. Food Chemistry 61: 429-433.
Coffman, C.W. & Garcia, V.V.(1977) Functional properties and amino acid content of
protein isolate from mung bean flour. Journal of Food Technology 12: 473-484.
Desikachar, H.S.R.(1980) Development of weaning food of high caloric density and low
hot paste viscosity using traditional technologies. Food Nutrition Bulletin 2: 21-23.
Edema, M.O., Sanni, L.O. & Sanni, A.I.(2005) Evaluation of maize-soybean flour blends
for sour maize bread production in Nigeria. African Journal of Biotechnology 4(9): 911917.
Fagbemi, T.N. & Oshodi, A.A.(1991) Chemical composition and functional properties of
full flat fluted pumpkin, Telferria occidentalis seed flour. Nigerian Food Journal 9: 26-32.
8
Fasasi, O.S., Adeyemi, I.A. & Fagbenro, O.A.(2005) Proximate composition and multienzyme in vitro protein digestibility of maize-tilapia flour blends. Journal of Food
Technology 3(3): 342-345.
Hoover, R. & Maunal, H.(1996) Effect of heat moisture treatment on the structure and
physicochemical properties of legumes starches. Foods Research International 29: 731750.
Hoover, R. & Sosulski, F.W.(1991) Effect of cross-linking on functional properties of
legume starches. Starch/Starke 38(5): 149-155.
Hoover, R. & Martin S.(1991) Isolation characterization of lima bean (Phaseolus lunatus)
starch. Journal of Food Biochemistry 15: 1117-1136.
Hutton, C.W. & Campbell, A.M.(1981) Protein functionality in foods, water and fat
absorption. American Association of Chemistry Society Symposium Series 147: 177-200
Ige, M.M., Ogunsua, A.O. & Oke, O.(1984) Functional properties of the proteins of some
Nigeria oil seeds: conophor seeds and three varieties of melon seeds. Journal of
Agricultural Food Chemistry 32: 822-825.
Kinsella, J.E.(1976) Functional properties of proteins in foods. Critical Reviews in Food
Science and Nutrition 1(3): 219-280.
Leach, H.W., McCowen, L.D. & Scoch, T.J.(1959) Structure of starch granule 1.
Swelling and solubility patterns of various starches. Cereal Chemistry 36: 534-544.
Lin, M.J.Y., Humbert, E.S. & Sosulski, F.W.(1974) Certain functional properties of
sunflower meal products. Journal of Food Science 39: 368-370.
Mitzner, K., Scrimshaw, N. & Morgan, R.(1994) Improving the Nutritional status of
children during the weaning period. Cambridge, MA: HOVIPREP (Home-and-village prepared weaning food) Publication, Massachusetts Institute of Technology.
Ogungbenle, H.N., Oshodi, A.A. & Oladimeji, M.O.(2002) Effect of salts on the
functional properties of benniseed (Sesamum radiatum) seed flour. International Journal
of Food Science and Nutrition 53: 5-14.
Okeiyi, L.C. & Futrell, M.F.(1983) Evaluation of protein quality of formulation of
sorghum grain and legume seeds. Nutrition Report International 28: 451-461.
Oshodi, A.A. & Adelakun, M.O.A.(1993) Proximate composition, some nutritionally
valuable minerals and functional properties of three varieties of lima bean (Phaseolus
linatus linn) flour. International Journal of Food Science and Nutrition 43: 181-195.
Oshodi, A.A. & Ekperigin, M.M.(1989) Functional properties of pigeon bean pea
(Cajanus cajan) flour. Food Chemistry 34: 187-199.
9
Oshodi, A.A., Ipinmoroti, K.O., Adeyeye, E.L. & Hall, G.M.(1995) In-vitro multienzyme digestibility of protein of six varieties of African yam bean flours. Journal of
Science of Food Agriculture 69: 373-377.
Osundahunsi, O.F., Fagbemi, T.N., Kesselman, E. & Shimoni, E.(2003) Comparison of
the physicochemical properties and pasting characteristics of flour and starch from red
and white sweet potato cultivars. Journal of Agricultural Food Chemistry 51: 2232-2236.
Popma, T. & Masser, M.(1999) Tilapia: life history and biology. Southern Regional
Agricultural Centre (SRAC) Publication, No. 283.
Salami, I.L.(1988) An assessment of the nutritional value of corn-pinto porridge as a
food. Journal of Arid Agriculture 1: 107-119.
Sathe, S.K. & Salunkhe, D.E.(1981a) Functional properties of lupin seed (Lupinus
mutabilis) proteins and protein concentrates. Journal of Food Science 46: 149-197.
Sathe, S.K. & Salunkhe, D.E.(1981b) Functional properties of the great Northern Beans
(Phaseolus vulgaris, L.) protein, emulsion, foaming, viscosity and gelation properties.
Journal of Food Science 46: 71-74.
Sathe, S.K., Desphande, S.S. & Salunkhe, D.K.(1982a) Functional properties of lupin
seed (Lupinus mutabilis) protein and protein concentrates. Journal of Food Science 47:
491-497.
Sathe S.K., Desphande, S.S. & Salunkhe, D.K.(1982b) Functional properties of winged
bean proteins. Journal of Food Science 47: 503-509.
Sefa-Dedeh, S.K.S., Asre, E.O., Dawson, S. & Afoakwa, E.O.(2002) Effect of
fermentation and cowpea fortification on the quality characteristics of maize based
nixtamilized foods. http:/ift.confex.com/ift/2002/techprogram/meeting.
Tagodoe, A. & Nip, W.K.(1994) Functional properties of raw and precooked taro
Colocasia esculenta flour. International Journal of Food Science and Technology 29:
457-482.
Vautsinas, L.P. & Nakai, S.(1983) A simple turbidimetric method of determining the fat
binding capacity of proteins. Journal of Agricultural Food Chemistry 31: 58-61.
10