Advance Journal of Food Science and Technology 4(3): 126-129, 2012
ISSN: 2042-4876
© Maxwell Scientific Organization, 2012
Submitted: October 05, 2011
Accepted: March 02, 2012
Published: June 25, 2012
Effect of Salts on the Emulsifying Properties of Adansonia digitata
(Baobab) Seed Flour
H.O. Adubiaro, O. Olaofe and E.T. Akintayo
Science and Technology Department, The Federal Polytechnical, Ado-Ekiti, Ekiti State, Nigeria
Abstract: The effect of salts NaCl, CaCl2 KCl, CH3 CO2 Na and NaNO3 on the emulsifying properties of
Adansonia digitata (Baobab) flour were investigated. Simple and objective means that allowed precise
determination of the inversion point was used in investigating the capacity of the protein to emulsify fat. Its
relative efficiency as emulsion stabilizer was also investigated. Results showed that the emulsion capacity
decreased with increase in salt concentrations and also there was a decrease in emulsion stability as time
increased and increase in stability as concentration increased.
Keywords: Adansonia digitata, concentration, efficiency, emulsion, inversion, precise
equipment, blender speeds, rate of oil addition, protein
source and concentration, temperature, or type of oil
affect emulsifying properties of proteins (Mcwatters and
Cherry, 1981). No standardized tests exist for evaluating
the emulsifying properties of proteins and in many cases
there seems to be little correlation between results
obtained in a model systems and those obtained in
performance trails in food system.
The method described in this work is a modification
of the Crenwelge et al. (1974) method. It is simple and
easily adaptable in that it enables formation of the
emulsion inside a beaker and allows precise determination
of the inversion point under standardized conditions by
sensitive and objective means.
The presence of salt may increase the total water
content of the protein system at specific water activity
values, although it may reduce the preferential binding of
water to the protein (Sathe and Salunkhe, 1981). These
effects are markedly dependent on the nature of the anion
and cation components (Sathe and Salunkhe, 1981;
Altschul and Wilcks, 1985). The effect of salt is
significant because, in many foods, salt concentrations are
approximately 0.2-0.3 M Altschul and Wilcks (1985).
The aim of this investigation was to determine and
compare the effect of NaCl, CaCl2, KCl, NaCH3CO2 and
NaNO3 on the emulsifying properties of protein from
Adansonia digitata (Baobab) so as to reveal its potentials
for use as food emulsifiers.
INTRODUCTION
The continuous increase in population and inadequate
supply of protein have in advertently increased the
occurrence of malnutrition in developing countries
(Siddhuraju et al., 1996). It is well documented that the
developing countries (Nigeria inclusive) do not produce
enough food and of the right nutritional qualities to meet
daily needs. The dearth in food supply especially that of
protein, is of such magnitude that the developing nations
have to depend, mostly on cereal grains, starchy roots and
tubers for their energy and protein needs (Aletor and
Aladetimi, 1989). In view of above, the search for
alternative source of protein from lesser known tree crops
become imperative. However, successful applications of
plant protein in food formulation depends largely on the
functional properties of the protein (Milner, 1962).
Emulsifying capacity and emulsion stability
measurements are often used in functional
characterization of proteins (Lin et al., 1974; Kinsella,
1979; Ige et al., 1984; Oshodi and Ekperigin, 1989). The
technique most commonly employed for measuring the
emulsion capacity of proteins is the model system, or
modification of it, developed by Swift et al. (1961). This
procedure involves the continuous addition of oil or
melted fat to a protein dispersion during high speed
mixing; oil is added until a sudden drop in emulsion
viscosity occurs due to separation of oil and water into
two phases. The volume of oil added until the
“breakpoint” is reached is used to express emulsion
capacity of a protein; these values may be expressed as
total ml of oil emulsified, ml of oil per unit weight of
sample, or ml of oil per unit of protein or nitrogen in the
sample. Comparisons of results obtained from different
studies is difficult because small variations in technique
MATERIALS AND METHODS
The Adansonia digitata seeds were collected from
Fulani women after they had removed the pulp for use in
making “Fura-da-nono” drink, in the Northern part of
Nigeria. The seeds were sun-dried, de-shelled, powdered
Corresponding Author: H.O. Adubiaro, Science and Technology Department, The Federal Polytechnical, Ado-Ekiti, Ekiti State,
Nigeria
126
Adv. J. Food. Sci. Technol., 4(3): 126-129, 2012
Table 1: Effect of salts on emulsion capacity of Adansonia digitata
(baobab). (Emulsion capacity ml of oil per g of soluble
protein)
Conc. of
NaCH3
salt used %NaCl
CaCl2
KCl
COO
NaNO3
0.0
320±3.1
320 ± 3.5 320 ± 4.8 320 ± 3.2
320 ± 4.0
0.5
290 ± 4.2
248 ± 4.8 284 ± 5.1 280 ± 2.6
194 ± 3.2
1.0
272 ± 3.6
222 ± 2.6 242 ± 3.6 252 ± 2.0
163 ± 4.0
2.0
205 ± 4.2
182 ± 6.3 206 ± 4.0 213 ± 3.2
152 ± 5.6
5.0
180 ± 3.1
103 ± 3.8 120 ± 3.1 182 ± 6.0
132 ± 4.8
10.0
100 ± 3.4
72 ± 3.2 93 ± 4.0 107 ± 4.0
70 ± 5.6
and stored in polythene bags until use. One hundred
percent pure cotton seed oil (specific gravity 0.98 at
250ºC) was chosen as the oil phase for this study. The
research was carried out in the year 2009 at Federal
Polytechnic, Ado Ekiti, Ekiti State, Nigeria.
Emulsifying capacity: Emulsions were formed inside a
600 mL beaker by use of continuous stirring apparatus;
this apparatus consisted of a regulated/stabilized 6v power
supply, a burette, a stirrer, a beaker with the emulsion and
a digital milliameter. The stirrer consisted of a stainlesssteel rod holding a perspex bridge fixed to a 6v d.c motor
spindle by means of a plastic adaptor. The motor itself
was driven by a regulated and stabilised 6v d.c power
supply. A milliameter monitored the current drawn by the
stirrer motor to maintain a constant speed, the greater the
viscosity of the emulsion the greater the current drawn. 1g
of protein flour was made into a slurry of 25 mL of water
in a Conical flask. The salts used were NaCl, CaCl2, KCl,
NaCH3COO and NaNO3; all chemicals used were of
analytical grade. The required concentrations of the
different salt solutions used were 0.5, 1.0, 2.0, 5.0 and
10.0 w/v, respectively. The mixture was stirred for 30 min
respectively. The mixture was stirred for 30 min in order
to disperse the sample. Oil was then added at a rate of
1.00 mLs-1 from a burette until the emulsion collapsed, as
indicated by a sharp fall in the motor current resulting
from the sudden breakdown in viscosity. The volume of
oil added up to this inversion point was noted and the
emulsifying capacity expressed as ml of oil per g of
protein.
Table 2: Stirrer currents drawn at
digitata (baobab)
Conc. of salt
used % NaCl
CaCl2
(Curre MA)
0.0
862 ± 6.2
862 ± 3.2
0.5
800 ± 8.6
740 ± 3.6
1.0
764 ± 3.8
700 ± 4.0
2.0
680 ± 4.6
401 ± 3.8
5.0
334 ± 4.5
225 ± 5.2
10.0
200 ± 4.6
186 ± 4.6
the inversion points of Adansonia
KCl
NaCH3
COO
NaNO3
862 ± 3.5
620 ± 4.0
520± 6.0
438 ± 3.8
125 ± 4.2
100 ± 4.0
862 ± 3.5
704 ± 6.2
658 ± 4.3
443 ± 5.0
203 ± 3.2
128 ± 5.6
862 ± 4.2
840 ± 3.6
760 ± 3.8
542 ± 3.5
216 ± 4.1
98 ± 2.3
Table 3: Emulsion stability of Adansonia digitata using NaCl
Salt concentrations
--------------------------------------------------------------------------Time (h) 0.0
0.5
1.0
2.0
5.0
10.0
0
15.9
17.6
22.0
25.1
27.0
26.4
0.5
15.0
17.4
21.1
23.0
26.0
24.2
1
15.0
17.0
18.5
20.0
25.0
24.2
5
13.1
17.0
18.0
19.2
24.8
23.4
10
8.2
10.4
14.5
15.8
20.1
23.4
24
8.0
10.0
14.3
15.3
19.0
23.4
48
7.6
8.8
14.0
15.1
18.4
22.8
72
5.0
7.0
14.0
15.0
18.0
22.6
120
5.0
7.0
10.4
13.0
14.5
16.5
144
0.0
3.4
6.0
9.3
11.3
16.0
168
0.0
3.0
4.0
7.1
9.1
12.1
336
0.0
0.0
1.3
4.5
5.0
8.4
Emulsion stability: The emulsion stability was
determined by following the procedure used for the
emulsifying capacity, except that 100 mL of oil was
added rather than adding oil until the emulsion
breakpoint. 1g slurry of protein in different concentration
of salt was made as used for emulsifying capacity. One
hundred mL aliquot of the Resultant Emulsion (RE) was
measured into a 100 mL graduated cylinder and allowed
to stand at room temperature (28 + 10ºC). The amount of
oil separated was noted after 0, 0.5, 1, 5, 10, 24, 48, 72,
120, 144, 168 and 336 h, respectively.
Table 4: Emulsion stability of Adansonia digitata using CaCl2
Salt concentrations
-------------------------------------------------------------------------Time (h) 0.0
0.5
1.0
2.0
5.0
10.0
0
18.4
21.1
25.0
28.0
26.4
24.8
0.5
15.2
19.0
22.3
24.0
24.8
22.6
1
11.5
17.4
20.1
21.3
24.8
20.4
5
9.0
11.0
16.3
18.4
24.8
20.4
10
7.6
10.2
13.4
17.2
23.2
18.8
24
6.8
8.4
11.1
16.0
21.0
18.6
48
6.0
8.0
10.0
14.4
20.5
16.4
72
5.2
8.1
9.4
12.1
19.4
14.2
120
4.3
6.5
7.1
11.4
17.3
14.1
144
2.8
4.1
5.8
8.0
15.5
12.2
168
1.5
2.8
4.2
7.4
14.6
10.0
336
0.6
1.4
2.3
5.2
11.2
10.0
RESULTS AND DISCUSSION
Table 1 shows the effect of salts on the emulsifying
capacity and Table 2 gives the stirrer currents required by
their emulsions near their inversion points. Table 1
revealed that for the Adansonia digitata (Baobab) flour,
the emulsion capacity decreased with increase in salt
concentrations which correspond with the currents
required in Table 2. These results agree with those of
other workers. Lin et al. (1974) on the emulsion capacity
of sunflower and soyabean flours and protein
concentrates/isolates; Sathe et al. (1982) on the emulsion
capacity of lupin seed protein concentrates, Oshodi and
Ojokan (1997) on the emulsion capacity of bovine plasma
protein concentrates; Akintayo et al. (1998) on the
emulsion capacities of pigeon pea, lima bean and African
yam bean protein concentrates.
The effect of salts on the emulsion stability of
Adansonia digitata are shown in Table 3 (NaCl), 4
127
Adv. J. Food. Sci. Technol., 4(3): 126-129, 2012
Table 5: Emulsion stability of Adansonia digitata using Kcl
Salt concentrations
------------------------------------------------------------------------Time (h) 0.0
0.5
1.0
2.0
5.0
10.0
0
17.8
20.6
23.2
29.1
32.0
34.6
0.5
15.4
19.2
21.4
25.2
28.0
32.8
1
14.3
16.4
20.2
23.1
25.4
32.8
5
12.9
13.5
17.4
19.0
22.1
30.0
10
10.2
13.0
15.1
18.4
20.4
28.4
24
9.1
11.4
13.0
15.1
19.3
27.8
48
7.0
9.0
10.4
11.2
18.0
25.6
72
6.0
7.6
8.0
10.0
17.4
24.2
120
4.2
7.0
8.0
8.6
16.5
20.0
144
3.8
5.8
6.4
7.9
14.2
18.2
168
3.0
5.2
5.0
6.0
11.0
14.1
336
2.4
3.2
4.6
5.4
9.5
13.2
the time increased. This corroborates the work of other
researchers; Ogungbenle (2008) on the emulsion stability
of gourd seed, white melon, yellow melon and Bulma
cotton seed, also Adeyeye and Aye (2005) on the
emulsion stability of Triticum durum flour.
The decrease in emulsion stability as time increased
might be due to increased contact leading to coalescence
which thereby reduced stability (Parker, 1987). Three
separate mechanisms that appear to be involved in the
formation of a stable emulsion may be:
C
C
C
Table 6: Emulsion stability of Adansonia digitata using NaCH3COO
Salt concentrations
---------------------------------------------------------------------------Time (h) 0.0
0.5
1.0
2.0
5.0
10.0
0
20.4
24.1
29.2
34.1
40.1
48.4
0.5
19.2
20.0
27.1
30.0
37.4
47.9
1
15.1
20.0
24.3
28.4
34.1
44.4
5
14.3
19.4
21.0
27.7
32.0
35.1
10
11.2
18.2
21.0
23.1
28.0
33.0
24
11.0
15.1
19.2
23.0
27.6
30.5
48
11.0
13.5
18.4
20.4
27.0
28.4
72
9.3
13.0
17.3
19.1
25.4
26.1
120
7.2
11.4
15.1
17.2
21.2
23.2
144
6.0
10.2
15.0
15.7
18.1
20.0
168
4.3
7.1
11.4
13.2
17.2
20.0
336
2.1
5.3
11.0
13.0
15.1
18.1
Reduction of interfacial tension
Formation of a rigid interfacial film
Electrical charge (Mcwatters and Cherry, 1981)
CONCLUSION
This work revealed that the Adansonia digitata flour
is a good source of protein. Its good emulsify capacity and
stability implied the usefulness of the flour in food
formulation and utilization in food industries. Also since
its emulsion capacity and stability were affected by salt
concentrations then salting may be selectively used to
improve or inhibit these functional properties of this
sample.
ACKNOWLEDGMENT
Table 7: Emulsion stability of Adansonia digitata using NaNO3
Salt concentrations
------------------------------------------------------------------------Time (h) 0.0
0.5
1.0
2.0
5.0
10.0
0
16.2
18.0
22.4
24.6
34.5
43.1
0.5
15.4
17.3
21.0
23.2
31.0
41.4
1
13.2
16.8
19.6
21.1
30.4
38.5
5
11.5
14.3
17.2
20.4
26.5
32.1
10
8.9
11.2
16.4
16.1
23.2
28.4
24
8.3
10.0
16.0
15.4
21.1
25.3
48
7.0
9.2
12.9
13.2
19.4
21.4
72
4.5
6.0
12.1
13.0
17.9
20.1
120
3.2
4.2
9.2
11.4
15.2
19.0
144
1.3
3.8
7.0
9.2
14.1
15.7
168
0.4
1.7
5.2
7.1
9.7
11.4
336
0.0
1.3
3.1
5.2
6.4
9.2
The authors wish to acknowledge the technical
assistance of Mr. J.E. Ukpong (Physics Electronics
laboratory) of the Federal Polytechnic, Ado-Ekiti, Ekiti
State.
REFERENCES
Adeyeye E.I. and P.A. Aye, 2005. Chemical composition
and the Effect of salts on the food properties of
Triticum durum Wholemeal flour. Pak. J. Nutr., 4(3):
187-196.
Akintayo E.T., K.O. Esuoso and A.A. Oshodi, 1998.
Emulsifying properties of some legume proteins. Int.
J. Food Sci. Technol., 33: 239-246.
Aletor, V.A. and O.O. Aladetimi, 1989. Compositional
evaluation of some cowpea varieties and some underutilised edible legumes in Nigeria. Dich. Nahrung.,
33(10): 999-1007.
Altschul, A.M. and H.L. Wilcks, 1985. New Protein
Foods: Food Science and Technology. F.L.
Academic Press, Orlando.
Crenwelge, D.D., C.W. Dill, P.T. Tybor and
W.A. Landman, 1974. A comparison of the
emulsification capacities of some protein
concentrates. J. Food Sci., 39: 175-177.
Ige, M.M., A.O. Ogunsua and O.L. Oke, 1984. Functional
properties of the proteins of some Nigerian oil seeds:
Conphor seeds and three varieties of melon seeds. J.
Agric. Food Chem., 32: 822-825.
(CaCl2), 5 (KCl), 6 (NaCH3COO) and 7 (NaNO3). The
sample emulsion stability were studied under room
temperature over a range of 0, 0.5, 1, 5, 10, 24, 48, 72,
120, 144, 168 and 336 h, respectively. The salt
concentrations as 0.0, 0.5, 1.0, 2.0, 5.0 and 10.0 g,
respectively. The capacity of protein to aid the formation
and stabilization of emulsion is important for many
applications in cake bakers, coffee whiteners, milk,
mayonnaise, salad dressings, comminuted meats and
frozen desserts (Kinsella et al., 1985).
The degrees of water separation vary from salt to salt.
However, the general trend for all the salt under
consideration in this work is that there is increase in the
volume of water separated with increase in salt
concentration but there is a general decrease in the
volume of oil separated (for each salt concentration) as
128
Adv. J. Food. Sci. Technol., 4(3): 126-129, 2012
Ogungbenle, H.N., 2008. Effects of salts concentrations
on the functional properties of some legume flours.
Pak. J. Nutr., 7: 453-458.
Parker, N.S., 1987. Properties and functions of stabilising
agents in food emulsions. Crit. Rev. Food Sci. Nutr.,
25(4): 112-129.
Sathe, S.K. and D.H. Salunkhe, 1981. Functional
properties of the Great Northern Bean (Phaseolus
vulgaris L.) proteins, emulsion, foaming, viscosity
and gelation properties. J. Food Sci., 46: 71-74.
Sathe, S.K., S.S. Deshpande and D.H. Salunkhe, 1982.
Functional Properties of lupin seed (Lupinus
mustabilis) proteins and concentrate. J. Food Sci., 47:
491-496.
Siddhuraju, P., K. Vijayakumari and K. Janardhanan,
1996. Chemical Composition and protein quality of
the little known legume, velvet bean (Mucuna
pruriens). J. Agric. Food Chem., 44: 2636-2641.
Swift, C.E., C. Lockett and A.J. Fryar, 1961.
Communited meat emulsions-The capacity of meats
for emulsifying fat. Food Technol., 15: 468-473.
Kinsella, J.E., 1979. Functional properties of soy proteins.
J. Am. Oil Chem. Soc., 56: 242-258.
Kinsella, J.E., D. Srinivasan and G. Bruce, 1985.
Physical, chemical and functional Properties of Oil
Seed Protein with Emphasis on Soy Proteins. In:
Altschul, A.M. and H.L. Wilcks, (Eds.), New Protein
Foods. Academic Press, New York, 5p: 107.
Lin M.J.Y., E.S. Humbert and F.W. Sosulki, 1974.
Certain functional properties o f s u n f l o w e r me a l
products. J. Food Sci., 39: 368-370.
Mcwatters, K.H. and J.P. Cherry, 1981. Emulsification:
Vegetable Protein. In: Cherry, J.P., (Ed.), American
Chemical Society Symposium Series. 147, pp: 217.
Milner, M., 1962. Protein food problems in developing
countries. Food Technol., 16(5): 51-52.
Oshodi A.A. and E. Ojokan, 1997. Effect of salts on some
of the functional properties of bovine plasma protein
concentrate. Food Chem., 59(3): 333-338.
Oshodi, A.A. and M.M. Ekperigin, 1989. Functional
properties of pigeon pea (Cajanus cajan) flour. Food
Chem., 34: 187-191.
129