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 American Journal of  
Food Science and Technology (AJFST)

Formulation of  an Improved Nutritional Quality Composite Flour for Bakery Products 
Using Wheat and Sologold Sweet Potato 
William Adebisi Olosunde1*, Tosin Paul2, Antia Orua O1

Volume 2 Issue 2, Year 2023
ISSN: 2834-0086 (Online)

DOI: https://doi.org/10.54536/ajfst.v2i2.1825
https://journals.e-palli.com/home/index.php/ajfst

Article Information ABSTRACT

Received: August 18, 2023

Accepted: September 22, 2023

Published: September 28, 2023

The formulation of  high nutritional quality composite flour for use in producing bakery 
products is essential and advantageous health wise to consumers of  these products. There-
fore in this study, various formulated ratios (0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 
70:30, 80:20, 90:10, and 100:0 denoted as A2, B9, B8, B7, B6, B5, B4, B3, B2, B1 and A1 
respectively) of  wheat and sologold sweet potato flour were made. The pure wheat A1 and 
pure sologold sweet potato A2 served as basis of  assessing the nutritional contribution 
of  sologold sweet potato flour at various ratios with wheat flour. The proximate proper-
ties, mineral, vitamins and beta carotene were determined in the various ratios formulated. 
More so, the best blend was selected based on desirability index of  the formulated com-
posite flours. Results revealed that B6 (40% wheat and 60% sologold sweet potato) had the 
highest desirability index of  0.65164. Hence, was selected as the best blend (composite) 
flour. The nutritional profile of  the chosen B6 sample are as follows:  moisture content 
(10.12%), crude fiber (3.21%), ash content (2.61%), protein content (5.80%), oil extract 
(5.20%), NFE (74.10%), sodium (0.13mg/g), calcium (2.08mg/g), magnesium (0.07mg/g), 
potassium (2.14mg/g), vitamin C (0.30µg/g), Vitamin A (24.6µg/g) and beta-carotene con-
tent (27.5µg/g). This profile showed valuable positive impact of  sologold sweet potato flour 
on the nutritional characteristics of  the developed B6 composite flour.  Comparison of  the 
blend B6 with some existing formulated composite flours, revealed that the developed com-
posite flour B6 will likely have added advantage to the well-being of  those that will consume 
its bakery products. Thus the B6 Blend (composite) flour is recommended for use in baking. 

Keywords

Bakery Products, Composite 
Flour, Nutritional Composition, 
Sologold Potato, Wheat

1 Department of  Agricultural and Bioresources Engineering, Michael Okpara University of  Agriculture, Umudike, Abia State, Nigeria
2 Department of  Agricultural and Food Engineering, Faculty of  Engineering, University of  Uyo, Uyo, Akwa Ibom State, Nigeria
* Corresponding author’s e-mail: williamolosunde@uniuyo.edu.ng

INTRODUCTION
Flour plays a crucial role in baking. It provides structure, 
texture and flavour to baked goods. Also, it is the 
foundation of  bread, cakes, cookies, pastries and other 
baked products (Tamaroh & Sudrajat, 2021). When 
wheat flour is hydrated and mixed, the gluten protein 
will form an elastic network. The network will trap gases 
produced by yeast or leavening agents. This leads to the 
rising of  dough coupled with a light, airy texture in the 
baked goods (Aziz et al., 2018; Oloniyo et al., 2021). Flour 
is a staple ingredient in many food products; and wheat 
flour is the most widely used. However, the increasing 
prevalence of  wheat-related allergies, dietary restrictions 
and the need for diversification in the food industry 
have prompted search for alternative sources of  flour 
(Ahemen et al., 2018; Tamaroh & Sudrajat, 2021). The 
potential sources of  flour other than wheat include maize, 
rice, barley, sorghum, millet, oat, legume flours (such as 
soybean, chickpea, lentil), tuber flours (such as cassava, 
potato) and other locally available grains and pulses. Two 
or more sources of  flour may be combined to harness 
the beneficial attributes of  each component (Aburime 
et al., 2020; Wang et al., 2020). It also create a versatile 
and balanced flour blend that can be used in various food 
applications. The composition of  composite flour can be 
varied to give the desired characteristics. (Azizi & Rao, 
2005; Samia, 2013; Pycia & Ivanisora, 2020). Composite 
flour could be used in various food applications, including 

bread, biscuits, cakes, pastries, noodles, and other bakery 
and food products (Haruna et al., 2018).
Chinelo & Nnenna (2016) studied the nutritional quality 
of  bread made from composite flour that consist of  
wheat, sweet potato (yellow fleshed) and tiger nut flours. 
The findings indicated slight decrease in the protein 
content of  the bread samples when sweet potato and 
tiger nut supplementation increases. More so, the crude 
fibre content was found to increase; but there was no 
significant change (P<0.05) in the ash and fat contents. 
Carbohydrate which was the major component ranged 
from 73.47– 79.42%.  Awolu et al. (2017) investigated a 
composite flour that consist of  rice, sweet potato and 
soybean flours. The result showed an increase in protein 
content above 10% when compared with 100% wheat 
flour. The composite (85.694% rice flour, 11.806% sweet 
potato and 2.5% soybean) and (95% rice flour, 2.5% sweet 
potato flour and 6.765% soybean), specifically had high 
levels of  ash, fibre and protein contents. In addition, all 
the samples had carbohydrate content above 70 g/100g.
Fabian & Nwamaka (2016) evaluated the nutrient 
compositions of  bread fortified with sesame seed. It 
was found that full fat and defatted sesame seed meal 
respectively had 31.28% and 46.00% carbohydrate, 
23.07% and 29.9% protein, 31.05% and 11.89% fat, and 
13.20% and 12.14% crude fibre. Fortification with sesame 
seed improved the nutrient composition and storage 
stability of  the bread. The fortification with 20% full 



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Am. J. Food. Sci. Technol. 2(2) 37-45, 2023

fat or defatted sesame seed flours respectively increased 
protein from 11.80% to 13.93% or 14.89%, crude fibre 
from 1.63% to 3.44% or 5.25%, fat from 0.15% to 6.80% 
or 3.85%, but decreased carbohydrate from 55.44% to 
50.37% or 48.68%. Lee-Hoon et al. (2017) determined 
the chemical properties of  VitAto potato flour (VitAto), 
orange-fleshed sweet potato flour (OFSP) and purple-
fleshed sweet potato flour (PFSP). The VitAto, OFSP 
and PFSP were at 20% with wheat flour. The composite 
was used to produce sponge cake. Sponge cake without 
sweet potatoes flour served as control (WSPSC). The 
chemical properties of  these prepared sponge cakes 
were determined. The proximate composition revealed 
that VitAto contained highest protein (4.59%) while 
PFSP had the highest ash (1.67%) and crude fiber 
(2.73%) content. Addo & Oyeleke (2004) evaluated the 
proximate compositions of  orange fleshed sweet potato 
and red Bambara groundnut for possible application 
in the production of  high protein and pro-vitamin A 
enriched snacks for consumers. The flour blends were 
formulated in ratio 60:40, 50:50, 40:60, 30:70 respectively 
for orange fleshed sweet potato and red bambara 
groundnut. The protein and fat were observed to increase 
from 12.95±0.05% (60:40) to 16.87±0.02% (30:70) and 
2.17±0.03% (60:40) to 3.05±0.04% (30:70) respectively. 
Ash and carbohydrate decreased from 2.52±0.04% 
(60:40) to 2.27±0.05% (30:70) and 60.38±0.44% (30:70) 
to 69.09±0.30% (60:40) respectively. 
However, one of  the varieties of  potato that seems 
to be essential for utilization as a blend with wheat is 
sologold sweet potato. This is due to its high nutritional 
composition, functional properties and sensory attributes 
(Adegunwa et al., 2017). The nutritional composition 
of  sologold sweet potato includes macronutrients 
(carbohydrates, proteins, and fats) and micronutrients 
(vitamins, minerals, and antioxidants). These specific 
attributes makes sologold sweet potato an attractive 
ingredient for composite flour formulation (Amandikwa 
et al., 2015). The utilization of  Sologold sweet potato 
will reduce food waste and also enhance its potential 
application in baked products. Generally, composite flour 

offers significant advantages in bakery products in terms 
of  improved nutritional profile, enhanced technological 
properties and economic viability (Liu et al., 2020; 
Obomeghei et al., 2020). Therefore, this study is aimed at 
formulating composite flour from Sologold sweet potato 
and wheat to have an improved nutritional qualities for 
bakery products.

MATERIALS AND METHODS
Equipment and Sourcing of  Materials
The major material used for this study was fresh sologold 
sweet potatoes, which was collected in Nigeria from 
National Root Crops Research Institute Umudike, Abia 
State and wheat flour (Dangote brand).  The equipment 
used were hammer mill, mechanical sieves, electronic 
weighing balance, stop watch, electronic dough mixer, 
electronic PH meter, desiccators, stirrer, volumetric flasks, 
pipettes, beakers, crucibles, bowls, soxhlet apparatus, 
digestion flask, rapid visco-analyzer, ultraviolet/infrared 
and spectrophotometer. 

Production of  Sologold Sweet Potato Flour 
Twenty kilograms (20kg) of  fresh sologold sweet potato 
tubers were washed thoroughly, drained and peeled. The 
tubers were chopped to chips of  5mm thickness and then 
soaked in 2.5% Sodium Metabisulphate for 30 minutes. 
The pre-treated sologold potato chips were drained and 
divided into one hundred and fifty grams (150g) each. The 
samples were then dried in hot air oven set at temperature 
of  550C. The samples were removed when constant 
weights were obtained in three consecutive readings. The 
dried chips were crushed and milled with hammer mill into 
flour. The milled flour was sieved to fine particle size range 
of  0.295 to 0.462 mm. The proximate properties of  the 
produced sologold sweet potatoes flour were carried out.

Production of  Wheat-Sologold Sweet Potato Flour 
Blend
The formulation of  composite flour was carried out 
using completely randomized design (CRD) as shown in 
Table 1.

Table 1: Wheat-sologold sweet potato flour formulation
Samples Flour Blend Ratio SSPF (g) WF (g)
A1 100% WF, 0% SSPF 0 300
B1 90% WF, 10% SSPF 30 270
B2 80% WF, 20% SSPF 60 240
B3 70% WF, 30% SSPF 90 210
B4 60% WF, 40% SSPF 120 180
B5 50% WF, 50% SSPF 150 150
B6 40% WF, 60% SSPF 180 120
B7 30% WF, 70% SSPF 210 90
B8 20% WF, 80% SSPF 240 60
B9 10% WF, 90% SSPF 270 30
A2 0% WF, 100% SSPF 300 0

SSPF= Sologold sweet potato flour, WF= Wheat flour   



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Determination of  the Proximate Properties of  
Composite Wheat-Sologold Sweet Potato Flour
The composite flour proximate properties such as crude 
protein, moisture content, crude fat, crude ash, crude 
fiber and carbohydrate were determined as prescribed by 
AOAC (2016). All analyses were carried out in triplicates 
and the average values were recorded.

Determination of  Moisture Content
Each sample (5g) were weighed into a porcelain dish of  
known weight and heated in a hot air oven at 105 oC for 
3 hours. The samples were then cooled in a desiccator 
and weighed. The samples were consequently heated, 
weighed and cooled until a constant weight was attained. 
The formula used to calculate the moisture content was: 
Moisture (g/100g) = (W2-W3) / (W2-W1) x 100           (1) 
Where:
W1 = Weight of  container + empty dish (g)
W2 = Weight of  container + sample before drying (g)
W3 = Weight of  container + sample after drying (g)
    
Determination of  Ash Content
Sample 5 g was weighed into a porcelain crucible dish 
and then placed in a muffle furnace set at 550 oC for 5 
hours until a white grey ash was obtained. The crucible 
was cooled in a desiccator and reweighed. The percentage 
ash content was calculated. 
The formula used was:
Ash (g/100g) = (W3-W1) / (W2-W1) x 100                    (2) 
Where:
W1 = Weight of  crucible
W2 = Weight of  crucible + sample before ash (g)
W3 = Weight of  crucible + sample after ash (g)

Determination of  Crude Protein
Crude protein contents of  the sample was determine 
using micro-Kjeldahl method. Each sample 2 g was 
weighed in a digestion flask. Tablet of  Kjeltec catalyst 
was added to each flask containing 15 ml of  concentrated 
sulphuric acid. Each flask was heated on pre heated 
digester set at 420 oC for about 30 minutes in a fume 
cupboard and digested until a clear homogenous mixture 
is obtained. After digestion, the flask was removed from 
the heater, cooled and the content diluted with about 
50 ml of  distilled water. The flask was then placed in 
the micro-Kjedahl analyzer (distillation unit) where it 
received 50 ml of  40% NaOH automatically. The mixture 
was subsequently heated up to release ammonia which 
was distilled into a conical flask containing 25 ml of  
2% boric acid for about 4 minutes. Addition of  mixed 
indicator; Bromocresol green and methyl red during the 
distillation process, the ammonia combined with boric 
acid form ammonium borate solution which was then 
titrated against 0.1 M hydrochloric acid until a purplish-
grey end point was attained. The percentage nitrogen 
was calculated. The % crude protein was obtained by 
multiplying % g nitrogen by a factor of  6.25.
Crude protein (g/100g) = % nitrogen x 6.25               (3)

Determination of  Crude Fibre
Crude fibre was determine according to the method 
of  Owoso et al., (2000). Each of  the sample (2g) was 
diluted in 100 ml distilled water in a conical flask 20 ml 
of  1.25% sulphuric acid was added and boiled gently for 
30 min. The sample was then cooled and filtered. The 
filtrate was subjected to treatment using 1.25% sodium 
hydroxide. The residue was washed with 20 ml of  ethanol 
and petroleum ether and then dried at 150 oC. The sample 
was weighed and ashed at 600 oC for 90 minutes, cooled 
and reweighed and the percentage of  crude fibre was 
calculated.

Determination of  Oil Extract
Oil extract was determine using the Soxhlet extractor 
with a reflux condenser and a distillation flask (previously 
weighed). 2g each of  the samples was weighed into a 
fat free extraction thimble plugged with cotton wool 
and placed in the appropriate chamber of  the extractor. 
The distillation flask was filled to two third capacities 
with petroleum ether and boiled on a heating mantle; 
the refluxing continued until the extractor siphones 
over 4 hours. Thereafter, n-hexane was recovered into a 
clean container until almost all was distilled out of  the 
distillation flask. The remaining solvent in the mixture 
without the oil in the distillation flask was evaporated by 
introducing distillation flask to an oven set at 70 oC. The 
flask was allowed to cool subsequently in a desiccator after 
which the final weight of  the flask was determined. The 
difference in the final and initial weight of  the distillation 
flask represents the oil extracted from the sample.

Determination of  Carbohydrate (Nitrogen free extract)
The % carbohydrate content (Nitrogen free extract) was 
calculated by differences:
Carbohydrate (%) = 100 – (% moisture + % ash content 
+ % crude protein + % crude fibre + % crude fat).     (4)                                                        

Determination of  Vitamins and Beta-Carotene of  
Composite Wheat-Sologold Sweet Potato Flour
The determination of  vitamins and beta-carotene of  
composite wheat-sologold sweet potato flour blends 
were carried out using AOAC (2016). 10 grams each 
of  the flour samples were weighed using analytical 
weighing balance. Each sample was then transferred 
to a clean, dry container and kept covered to prevent 
moisture absorption. 60% ethanol was used as solvent 
for extraction of  vitamins. 100 mL of  the solvent was 
added to 2grams of  each flour sample. The mixture was 
stirred thoroughly for 5 minutes and thereafter allowed to 
settle for 30 minutes. The mixture was then centrifuged 
at 3000 rpm for 10 minutes to separate the liquid extract 
from solid particles. Series of  standard solutions of  
vitamin A, vitamin C and beta-carotene were prepared 
with known concentrations. Spectrophotometer was used 
to measure the absorbance of  each standard solution at 
specific wavelengths relevant to each vitamin. Calibration 
curves were plotted for each vitamin by plotting the 



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absorbance values against the corresponding known 
concentrations. The concentrations of  vitamin A, vitamin 
B, and beta-carotene in each flour sample was obtained 
from the calibration curves. The results were expressed 
in micrograms per gram to quantify the level of  each 
vitamin in each flour sample.

Determination of  the Minerals in Wheat-Sologold 
Sweet Potato Composite Flour
The determination of  the mineral’s composition in wheat-
sologold sweet potato flour blends was carried out using 
AOAC (2016). 5grams of  each flour sample was weighed 
using analytical weighing balance. The flour sample was 
transferred into a digestion vessel followed by addition of  
100mL concentrated nitric acid. The digestion vessel was 
covered and heated using a Bunsen burner until digestion 
was completed and thereafter allowed to cool to room 
temperature. The digested sample was then transferred 
to a volumetric flask and diluted with deionized water to 
500mL; then mixed thoroughly to ensure homogeneity. 

The diluted sample was filtered and the undissolved 
particles discarded while the filtrate was collected in a clean 
container. The atomic absorption spectrophotometer was 
used to obtain calibration curves for each of  the mineral 
to be tested in the sample. The absorbance or emission 
intensity of  the diluted and filtered sample was measured 
and used to determine the concentration of  each mineral 
based on the calibration curve. Calculation of  the mineral 
content in each flour sample was done by multiplying the 
concentration of  each mineral element by the dilution 
factor and the weight of  the original sample. The results 
were expressed in milligrams per gram of  each flour 
sample.

RESULTS AND DISCUSSION
Proximate Composition of  Wheat-Sologold Sweet 
Potato Composite Flour
The proximate properties of  the wheat-sologold sweet 
potato flour blends determined are as presented in Figure 1.
The average moisture content of  the flour samples 

Figure 1: Proximate properties of  wheat-sologold sweet potato flour blends

range between 9.60%- 11.90%. Sample B1 with 90.00% 
wheat flour and 10.00% SSPF recorded the highest value 
of  moisture content (11.90%); while B9 with 10.00% 
wheat flour and 90.00% SSPF recorded the lowest value 
of  9.60%. The average moisture content of  sample A1 
(100% wheat and 0% SSPF) and sample A2 (0% wheat 
and 100% SSPF) were 12.02% and 9.52% respectively. 
However, flour with water activity range of  6-12% is 
considered as intermediate water activity flour. (Malomo 
et al., 2012). This implies that the composite could have 
reasonable life span before microbial spoilage. Moreover, 
the ash content of  the composite flour samples is not 
significant (p˃0.050) and ranges between 4.62% - 0.96% 
with blend A1 having lowest value (0.96%) and blend 
A2 highest value (4.62%). This shows that the sologold 
sweet potato flour supplies the blend with minerals. The 
average crude protein content of  the flour blends ranges 
between 6.35% - 3.96%. Blend B1  (90.00% wheat flour 
and 10.00% SSPF) recorded the lowest value (3.96%) 
while blend B9 (90.00% wheat flour and 10.00% SSPF) 
recorded the highest value of  6.29%.
However, sample A1 (100% wheat and 0% SSPF) 

recorded average crude protein content of  3.76% while 
sample A2 (0% wheat and 100% SSPF) recorded 6.35%. 
This indicates that the major supplier of  crude protein 
in the blend is sologold sweet potato. The average crude 
fibre content of  the entire flour blends ranges between 
4.08% - 1.31%. Blend B1 (90.00% wheat flour and 10.00% 
SSPF) recorded the lowest value (1.31%) while blends 
B9 (10.00% wheat flour and 90.00% SSPF) recorded the 
highest value (3.72%). However, sample A1 (100% wheat 
and 0% SSPF) recorded average crude fibre content of  
1.03% and sample A2 (0% wheat and 100% SSPF) has 
4.08%. Therefore, sample A2 (sologold sweet potato) is a 
good source of  fibre and may compensate the deficiency 
in daily dietary fibre. According to Malomo et al., (2012) 
high content of  dietary fibre has an impact on food by 
reducing the rate of  glucose breakdown and absorption. 
The oil extract content of  Blend B1 (90.00% wheat flour 
and 10.00% SSPF) was the lowest with value of  4.78% 
while blend B9 (10.00% wheat flour and 90.00% SSPF) 
recorded the highest value of  5.48%. However, sample A1 
(100% wheat and 0% SSPF) average oil extract content of  
was 4.70% while sample A2 (0% wheat and 100% SSPF) 



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recorded 5.63%. Oil extract is important since it enhances 
the organoleptic and preservative properties especially 
when available at optimum percentage. More so, analysis 
on Nitrogen free extract (NFE) in the composite flour 
showed that blend B6 with 40.00% wheat flour and 
60.00% SSPF had the lowest value (74.10%) while blend 
B9 (10.00% wheat flour and 90.00% SSPF) recorded the 
highest value of  78.20%. The sample A1 (100% wheat 
and 0% SSPF) recorded average NFE of  77.55% and 
sample A2 (0% wheat and 100% SSPF) recorded 72.24%. 

The nitrogen free extract (NFE) indicates the presence 
of  non-fibrous and soluble carbohydrate such as sugars 
and starches. Also samples with high NFE are more 
digestible than those with low NFE. Generally, based on 
the proximate composition of  each blend, the composite 
flour B6 was considered and preferred to have good 
nutritional attributes. The statistical analysis of  variance 
carried out on the proximate properties of  the wheat-
sologold sweet potato blends are presented in Table 2.
From Table 2, the average moisture content of  the flour 

Table 2: ANOVA of  the Proximate Composition of  composite wheat-sologold flour
Composition Sum of  Squares Df. Mean   Square F Sig.
MC Between Groups 33.58208 24 1.399253 0.0690 1.6432

Within Groups .021 1 .002
Total 25

Protein Between Groups 115.4589 22 5.248133 13.1284 0.0358
Within Groups .076 1 .006
Total 23

Ash Between Groups 3.970558 24 0.016544 0.301059 0.5883
Within Groups .00 1 .000

25
Crude fibre Between Groups 2.264032 23 0.098436 0.0443 0.8554

Within Groups 1.43 1
Total 24

Oil extract Between Groups 18.8314 1 0.856234 3.062318 0.4112
Within Groups      0.5 22
Total 23

NFE Between Groups 194.1467 1 8.089446 6.487882 0.0372
Within Groups .001 24 .000
Total 1011.583 25

blends is not significant (p˃0.050).  More so, average 
protein content of  the flour blends showed that the 
difference in the protein content of  the composite flour 
samples is significant (p ≤ 0.050). The average crude 
fibre content of  the flour blends showed that the fibre 
content of  the composite flour samples is not significant 
(p˃0.050). Also, the average oil extract content of  the 

flour blends is not significant (p˃0.050). However, 
average nitrogen free extract content of  the composite 
flour samples is significant (p≤0.050). This implies that 
the composite flour samples are soluble carbohydrates.

Mineral Composition of  Composite Wheat-Sologold 
Flour

Figure 2: Mineral composition of  composite wheat-sologold sweet potato flour blends



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The mineral composition and its ANOVA for wheat-
sologold sweet potato composite flour blends are 
presented in Figure 2 and Table 3 respectively.
The sample, (A1) with 100% wheat and 0% SSPF 
recorded low values of  mineral compositions when 
compared with SSPF and the composite flour. This 
may be attributed to the high mineral content of  SSPF. 
Also, the statistical analysis of  variance showed that the 
magnesium and iron contents of  the composite flour 
samples are not significant (p>0.050). Moreso, calcium, 
sodium and potassium contents are significant (p≤0.050). 

The higher percentage of  calcium, sodium and potassium 
in sologold sweet potato flour influenced the composite 
flour samples. Generally, blend B6 chosen based on 
proximate composition of  the composite flour contains 
reasonable percentages of  these minerals.

Vitamin Composition of  Composite Wheat-Sologold 
Flour
The vitamin composition and ANOVA of  composite 
wheat-sologold sweet potato flour blends are given in 
Figure 3 and Table 4 respectively.

Table 3: ANOVA of  the mineral composition of  composite wheat-sologold flour
Composition Sum of  Squares Df. Mean   Square F Sig.
Ca Between Groups 314.58 1 9550.63 4.1909 0.029

Within Groups 5 8 .02
Total 319.58 9

Na Between Groups 274.02 1 3277.81 3.6907 0.043
Within Groups 5 8 .04
Total 279.02 9

Mg Between Groups 299.94 1 5198.80 9.4308 0.309
Within Groups 5 8 .03
Total 304.94 9

K Between Groups 303.61 1 7158.7 4.0407 0.018
Within Groups 5 8 .01
Total 308.61 9

Fe Between Groups 306.11 1 6301.55 1.5907 0.122
Within Groups 5 8 .05
Total 311.11 9

Figure 3: Vitamin composition of  composite wheat-sologold sweet potato flour blends

Table 4: ANOVA of  the vitamin composition of  composite wheat-sologold flour
Composition Sum of  Squares Df. Mean   Square F Sig.
Beta 
Carotene

Between Groups 938.98 3 94965.6 0.772828 0.045
Within Groups 3 8 .02
Total 941.98 11

Vitamin A Between Groups 199.627 3 91920.5 0.723912 0.036
Within Groups 3 8 .04
Total 199.630 11



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Vitamin C Between Groups 735364 3 66542.34 0.723912 0.040
Within Groups 6 8 .05
Total 735370 11

The sample A1 (100% wheat and 0% SSPF) recorded 
zero value for beta-carotene, vitamin A and C. However, 
sample A2 (0% wheat and 100% sologold sweet potato) 
had beta-carotene vitamin A and C. Hence the presence 
of  these vitamins in the composite flour is attributed to 
the high vitamin content of  SSP flour. From Table 4, 
the statistical analysis of  variance for average vitamin 
composition of  the flour sample blends shows that the 
difference in the beta carotene, 
vitamin A and vitamin C contents of  the composite flour 

samples are significant (p≤0.050).  However, 
sample blends with high vitamins and beta carotene are 
high in antioxidants and may enhance the immune system 
and protect the body from free radicals. In overall, the B6 
composition is well fortified with these vitamins. 

Desirability Index of  Nutritional Properties of  
Composite Wheat-Sologold Sweet Potato Flour
The desirability index of  all the nutritional properties of  
composite wheat-sologold sweet potato flour is shown 

Table 5: Desirability index of  nutritional properties of  composite wheat sologold sweet potato flour 

Sa
m

Pl
e

W
F

SS
PF

B
et

C
µg

/g

V
itA

µg
/g

V
it 

C
µg

 /
g

M
C

%

A
C

 %

C
P 

%

C
F 

%

O
E

 %

N
FE

%

C
am

g/
g

N
am

g/
g

M
gm

g/
g

K
m

g/
g

D
es

ira
bi

lit
y

A1

10
0

 0 0.
0

0.
0

0.
0

12
.0

2

0.
96

3.
76

1.
03

4.
70

77
.5

5

1.
90

0.
15

0.
10

2.
37

0.
33

20
5

B1

90 10 06
.3

03
.1

0.
07

11
.9

0

1.
25

3.
96

1.
31

4.
78

73
.4

3

2.
05

0.
15

0.
09

1.
52

0.
38

32
0

B2

80 20 11
.1

07
.4

0.
11

11
.8

6

1.
40

4.
53

1.
68

4.
86

75
.8

2

2.
07

0.
14

0.
09

2.
20

0.
49

88
1

B3

70 30 16
.5

12
.5

0.
16

11
.1

4

1.
57

4.
82

1.
89

4.
90

72
.8

7

2.
10

0.
14

0.
08

1.
71

0.
56

58
5

B4

60 40 20
.6

15
.2

0.
22

10
.5

4

1.
95

5.
15

2.
68

5.
00

75
.2

3

2.
09

0.
14

0.
08

2.
17

0.
55

48
3

B5

50 50 23
.2

19
.0

0.
25

10
.3

5

2.
18

5.
62

3.
11

5.
13

72
.4

2

1.
95

0.
13

0.
08

1.
86

0.
50

43
3

B6

40
   

   
 

60 27
.5

24
.6

0.
30

10
.1

2

2.
61

5.
80

3.
21

5.
20

74
.1

0

2.
08

0.
13

0.
07

2.
14

0.
65

16
4 Selected

B7

30 70 30
.6

0.
30

35
.8

5

9.
83

2.
89

5.
92

3.
28

5.
31

72
.7

7

2.
02

0.
12

0.
07

1.
92

0.
60

76
2

B8

20 80 35
.0

0.
33

40
.5

0

9.
74

3.
37

6.
15

3.
30

5.
40

73
.4

6

2.
04

0.
12

0.
07

2.
10

0.
60

18
7

B9

10 90 38
.2

0.
35

45
.2

5

9.
60

4.
12

6.
29

3.
72

5.
48

72
.3

0

2.
01

0.
11

0.
06

2.
00

0.
59

66
0

A2

0 10
0

42
.4

0.
38

47
.1

8 

9.
52

4.
62

6.
35

4.
08

5.
63

72
.2

4

2.
06

0.
10

0.
05

2.
04

0.
52

04
7



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Am. J. Food. Sci. Technol. 2(2) 37-45, 2023

in Table 5.
The sample with the highest desirability is selected as the 
optimum composite flour sample.  The selected sample 
is B6 with 40% wheat and 60% sologold sweet potato 
flour and has 0.65164 desirability. This indicates that B6 
is the optimum composite flour, and it is likely to give 
the desired qualities of  bakery product with the following 
attributes: moisture content (10.12%), crude fibre 
(3.21%), ash content (2.61%), protein content (5.80%), 
oil extract (5.2%), carbohydrate, NFE (74.1%), calcium 

(2.08mg/g), sodium (0.13mg/g), potassium (2.14mg/g), 
vitamin C (0.3µg/g), Vitamin A (24.6µg/g) and beta-
carotene content (27.29µg/g).

Comparative Analysis of  Selected Existing 
Composite Flours and the Wheat-Sologold Sweet 
Potato Composite Flour Used for Bakery Products
The nutritional properties of  the chosen best blend 
(composite flour) B6 developed were compared with 
some selected existing composite flour meant for bakery 

Table 6: Some nutritional properties of  selected existing composite flour samples and the developed composite flour (B6)
Composite Flour Blend 

ratio
Protein 
(%)

CHO 
(%)

Fat 
(%)

Fiber 
(%)

Vitamins Minerals (mg/g) Reference

Wheat-sologold 60:40 5.8 74.1 5.2 3.21 A,C, β-car 
otene

Sodium, calcium, 
magnesium, 
potassium

Researcher 
(authors)

Rice, potatoes and 
soybeans

85:12:3  12.5 74.2 8.4 1.9 B Magnesium Awolu et al., 
(2017)

Wheat-yam 60:40  6.9 66.3 6.9 3.6 B Magnesium, 
Phosphorus

Amandikwa et 
al., 2015

Wheat- corn 70:30   2.3 78.5 1.2 4.3 B Magnesium, 
Potassium

Aburime et al., 
2020

Wheat-soybeans 80:20  14.9 30.6 21.1 3.2 B Iron, Calcium, 
Potassium

Lee-hoon et al., 
(2017)

Wheat, potato and 
bambara nut

60:30:10  16.9 60.4 6.0 2.1 B Iron, Magnesium Addo & 
Oyeleke (2004)

Wheat-sesame 80:20  13.9 48.8 3.9 3.4 B Iron, Magnesium, 
Phosphorus

Fabian & 
Nwamaka 
(2016)

Wheat, tiger nut 
and potatoes

70:20:10  3.8 73.5 2.2 2.8 B Calcium, Iron, 
Magnesium

Chinelo & 
Nnenna (2016)

Wheat-Coconut 70:30  4.0 57.0 16.0 4.0 C Iron, Potassium Adegunwa et al., 
(2017)

Wheat-vitAto 
potato

80:20  4.6 81.5 0.8 2.2 A Iron, Magnesium Lee-hoon et al., 
(2017)

products and are presented in Table 6.
The composite flour samples in Table 6 shows that 
the blends with grains, legumes and tubers have high 
nutritional compositions. Hence, grains, legumes and 
tubers are recommended as composite constituents. In 
addition, the developed composite flour (B6) has added 
advantage of  containing more minerals and vitamins 
content than existing composite flour from various 
studies as presented.

CONCLUSION
The nutritional qualities of  the developed composite 
flour (40% wheat and 60% sologold sweet potato) will 
likely have positive impact on the health of  the consumer 
of  its bakery products.

RECOMMENDATION
The 40% wheat and 60% sologold sweet potato composite 
flour (B6) should be encouraged for utilization in Bakery 

products.
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