Effect of Substitution of Chicken Egg with Duck Egg on Biscuit Quality
F.M. Makinde1*, K.D. Awoyera2, A.O. Oguntunji3
1,2Department of Food Science and Technology, Bowen University, Iwo, Osun State, Nigeria
3Department of Animal Science and Fisheries Management,
Bowen University, Iwo, Osun State, Nigeria
Keywords: Biscuit, eggs, nutrition, cholesterol, quality.
Abstract. Eggs are characterized with other components such antioxidants, folic acid and other B
vitamins, and unsaturated fats which might have beneficial effects on heart disease risk that
counterbalance the small adverse effect of the eggs’ cholesterol content. A specific study of the effect
of chicken egg and/or duck egg in biscuit production has allowed the determination of their respective
effects on baking, chemical and sensorial properties. Five sample blends of chicken and duck eggs
were made respectively from the following ratios: 0, 10:90, 20:80, 30:70, 40:60 and 50:50%,
respectively. Baking and nutritional properties of samples of biscuit were determined by standard
methods, while sensory evaluation was also carried out. The results on the biscuit samples revealed
the following ranges: baking properties (weight 14.53-14.85g, diameter 48.4-50.04mm, thickness
9.37-9.46mm, bulk density 0.61 to 0.82g/cm3 and spread ratio 5.12-5.37; proximate parameters
(moisture 3.22-4.78%, ash 0.64-1.74%, fibre 0.49-0.51%, protein 9.4-12.9%, fat 15.8-19.2%,
carbohydrate 62.4-68.8% and energy 397.67-411.85kcal/g). Biscuit samples contained varying
amounts of calcium, phosphorus, potassium, magnesium, zinc and iron. Baking properties showed a
decrease in the weight and thickness but increase in diameter and spread ratio of the biscuits with
rising levels of substitution. The chemical analysis results revealed that biscuit samples containing
different levels of duck egg had significantly higher fat, ash and protein content but lower moisture
and carbohydrate than the control. Mineral concentration was significantly affected (p≤0.05) by the
substitution with duck egg in the biscuit formulations. The substitution of chicken egg with duck egg
at a level of up to 40% produces biscuit without any negative effect in quality attributes and
reasonable acceptance. Conclusively, the substitution of chicken egg with duck egg in biscuit
production is an ideal approach to utilizing uncommon food ingredients. The use of duck egg
produced biscuit with different characteristics and quality, depending on level of inclusion in the
formulation, offering nutritious and healthy alternative to consumers.
Biscuits are one of the confectionary food product consumed in Nigeria. They are ready to eat,
nutritive snacks produced from unpalatable dough that is transformed into appetizing product through
the application of heat in the oven . They are convenient and inexpensive food product containing
digestive and dietary properties of vital importance . The principal ingredients are flour, fat, sugar
and water; while other ingredients include milk, egg, salt and aerating agent . The importance of
egg is mainly due to the fact it has unique ability to form a cohesive gluten network in the dough in
the presence of water. Beaten egg white is used, like baking powder, to give the dough light, airy
texture. This is achieved because egg white (albumin) contains lecithin, a protein which lines the
outside of the air bubbles created when the egg was beaten and so prevents them from collapsing
Egg could be produced from different breeds of chicken, duck, roe, and caviar; however by a
wide margin the egg most often humanly consumed is the chicken egg, typically unfertilized .
Duck produces egg of larger size and more nutrients than chicken. It contains higher proportions of
protein and dry matter comparatively . The previous study also reported that duck eggs are packed
with vitamins and minerals even with their bigger size, their nutritional value is three to four times
Sustainable Food Production Submitted: 2018-10-22
ISSN: 2624-876X, Vol. 5, pp 38-47 Revised: 2018-12-13
doi:10.18052/www.scipress.com/SFP.5.38 Accepted: 2019-01-09
2019 SciPress Ltd., Switzerland Online: 2019-02-27
SciPress applies the CC-BY 4.0 license to works we publish: https://creativecommons.org/licenses/by/4.0/
greater than chicken eggs . Regular consumption of duck eggs leaves human body more alkaline
which is a great benefit to cancer patients as cancer cells do not thrive in an alkaline environment
unlike chicken eggs which makes body more acidic . The effectiveness of chemotherapeutic agents
adopted in cancer treatment is markedly influenced by pH. Death of cell correlates with acidosis and
higher shifts in intracellular pH (more alkaline) after chemotherapy may reflect a response to
chemotherapy . However, there is no scientific literature establishing the benefit of an alkaline diet
for the prevention of cancer at this time.
However, there is continued less utilization of duck eggs in food formulation solely because the
yolk contains more cholesterol than chicken eggs. Surprisingly, consumers are only just beginning to
understand the real effects of eating fat in daily diet. In practice, healthy active people who exercise
need fat in their diet; otherwise their bodies would generate the cholesterol itself. Several recent
studies have assessed the relationship between intake of eggs and/or dietary cholesterol and blood
cholesterol levels or heart disease risk in free-living groups of people. In a study of more than 20,000
male smokers in Finland, no association was found between dietary cholesterol intake and the risk of
death from heart disease over a six-year period . This study is of special interest because the
cholesterol intakes of the study participants were higher than those usually seen in United States
studies. No relationship between egg intake and heart disease risk in these studies because eggs are
characterized with other components such as antioxidants, folic acid and other B vitamins, and
unsaturated fats which might have beneficial effects on heart disease risk that counterbalance the
small adverse effect of the eggs’ cholesterol content . Furthermore, the American Heart
Association dietary guidelines for healthy people no longer include a specific limitation on the
number of eggs or egg yolks that a person may consume in a week . Duck egg is an important
source of high-quality protein in the diets of rural people whose traditional foods are typically rich in
carbohydrate but low in protein.
The vexed question of the cholesterol content of eggs and human health seems to have been over
exaggerated. The aim of this research is to examine the effect of substitution of chicken egg with
duck egg on the physical, nutritional and sensorial qualities of biscuit.
Materials and Methods
Procurement of raw materials
Fresh indigenous duck egg and chicken egg used for this study were purchased from Animal
Research Farm, Bowen University. Wheat flour and baking ingredients such as salt, sugar, baking
powder, and margarine were purchased from Odo-Ori market in Iwo, Osun state. All the chemicals
used in this analysis were of analytical grade.
Table 1 shows the different combination of duck egg and chicken egg for biscuit preparation and
the various ingredients are presented in Table 2.
Production of biscuit
Biscuits were produced from the blends using the method described by Onabanjo . All the
ingredients were weighed accurately. The pre-weighed flour, sugar, salt and baking powder were
mixed thoroughly. The shortening (margarine) and beaten egg were added to the mixture and mixed
until the uniform smooth dough was obtained. The dough was then transferred to a clean tray and
gently rolled using a roller. The dough sheath was cut into round shapes using a cutter. Shaped dough
pieces were placed into a greased pan, kept at a normal room temperature for 2 hr to allow proper
dough leavening and baked in a preheated laboratory oven operating at 217°C for 12 min. After
baking the biscuits were allowed to cool and packed in high-density polyethylene film and stored at
room temperature for subsequent analyses. The biscuit samples produced from 100% chicken egg
served as control.
Sustainable Food Production Vol. 5 39
Table 1. Different combination of duck egg and chicken for biscuit production
Chicken egg (%)
Duck egg (%)
Table 2. Laboratory formulations of raw materials used in the preparation of biscuits (g)
Determination of baking properties
Baking properties of the biscuit samples were determined according to AACC  methods.
The weight of three biscuits from each sample was determined on an electronic weighing balance
(Mettler, Germany) and average recorded in grams (g). The analysis was carried out in triplicate.
The diameter of biscuit samples was determined using a vernier calliper with zero error. Three
well- formed biscuit samples from each sample were arranged edge to edge and their diameter was
determined and the average was taken and recorded in millimetre (mm). The analysis was carried out
The thickness of the biscuit samples was measured using a micrometer screw gauge (zero error).
Thickness was measured by stacking three well-formed biscuits on top of one another, then restacking
in a different order and measuring them to get the average in millimetres. The analysis was carried
out in triplicate.
The spread ratio of the biscuit samples was determined by dividing the average value of the
diameter by average value of thickness of same biscuit samples.
The bulk density was determined using the method as described by Okaka and Potter . The
biscuit sample was milled (Wiley mill, 30 mesh). A known weight of milled biscuit sample was
poured into a clean and dry measuring cylinder. The measuring cylinder containing the milled biscuit
sample was tapped slightly several times and stopped when there was no further reduction in volume
of milled biscuit. The final volume was recorded and bulk density (g/cm3) was calculated using the
Bulk density =Weight of milled sample before tapping
Volume of milled sample after tapping
40 Volume 5
Determination of chemical composition
The proximate composition (moisture, protein, fat, ash and fiber) of different flour and biscuit
samples were determined using standard procedures . Carbohydrate content was determined by
difference. The energy value was estimated (kcal/g) by multiplying the percentage crude protein,
crude lipid and carbohydrate by the recommended factor (2.44, 8.37 and 3.57 respectively) as
described by Ekanayake et al. . All analyses were carried out in triplicate.
Determination of mineral composition
Analysis of potassium content of the samples was carried out using flame photometry AOAC
. Phosphorus content was determined by the phosphomolybdate method . The other elemental
contents (Ca, Mg, Fe and Zn) were determined, after wet digestion of sample ash with an atomic
absorption spectrophotometer (Hitachi Z6100, Tokyo, Japan). All the determinations were carried
out in triplicates.
Sensory evaluation of biscuit samples from various blends was conducted using untrained 25-
member panel. The panel comprised a broad cross section of adult population (students and staff) of
the Bowen University, with panellists spread across a wide range of age, education and income
groups. Biscuit samples were prepared a day ahead of sensory evaluation and stored at room
temperature. Samples were served in a randomized order on a tray, with portable water and spit cup
for rinsing mouth in between tasting of samples to minimize rating errors, due to carry over of
perceived attributes of previous sample. The panellists were asked to evaluate each sample based on
the following parameters of colour, taste, flavour, texture, crunchiness, sweetness and overall quality
using a 5-point Hedonic scale (5- like extremely and 1- dislike extremely) as described by Onwuka
Data obtained were statistically analyzed using a one-way analysis of variance (ANOVA) and
means were separated by Duncan’s New Multiple Range Test (DNMRT) using the Statistical Package
for Social Sciences (SPSS) version 17. Significance was accepted at 0.05 probability level.
Results and Discussion
Baking quality of biscuit samples
The biscuit quality parameters are given in Table 3. The weight and diameter of the biscuit
samples ranged between 14.53-14.85g and 48.40-50.40mm respectively. Biscuit weight was found to
be decreasing by the substitution of chicken egg with duck egg. Higher fat content in duck egg
compared to chicken egg contributes to a reduction in weight of biscuit which is then characterized
by a friable structure. The diameter of biscuit samples increased with the inclusion of duck egg
compared to the control (sample T-0). It has been reported that duck egg contains more fat than
chicken egg . Consequently, recipes with different levels of duck egg (samples T-1, T-2, T-3, T-
4 and T-5) required little water to produce cohesive and soft dough. During mixing, the fat coats the
flour particles and this inhibits hydration and interrupts gluten formation. The low dough viscosity
results in high flow rate (spread rate) of the dough and contributes to large diameter of biscuit samples
containing duck egg in their formulation.
Thickness was significantly different among the biscuit samples. Substitution of chicken egg
with duck egg negatively affected the thickness of biscuit. The decrease in the thickness of biscuit
sample containing a varying proportion of chicken egg and duck egg was due to the dilution of gluten.
Higher fat content noted in samples containing duck egg brought about decrease in dough viscosity
and subsequent decrease in thickness . The bulk density of the snack samples ranged from 0.61-
0.82 g/cm3 with samples T-3 and T-5 having the highest value, while sample T-0 had the least. Bulk
density is a reflection of the load the samples can carry if allowed to rest directly on each other and
the attribute is very important in determining raw material handling and packaging requirement .
By calculating the ratio between the diameter and the thickness of the biscuits, a significant increase
Sustainable Food Production Vol. 5 41
(p≤0.05) was recorded as the level of substitution of chicken egg with duck egg and increased. The
low spread ratio value of sample T-0 showed that starch polymer molecules in wheat flour are highly
bound with the granules and swelling is limited when heated. On cooling, the starch rapidly forms a
rigid gel with capacity characteristics of large molecular aggregates . However, substitution of
chicken egg with duck egg containing more protein affects the rheological properties of the dough
and its subsequent finished products. The increase in spread ratio is an indication of poor cohesion of
the network of the protein and carbohydrates which are the principal nutrients in the products. The
poor cohesion could allow the outflow of some ingredients such as sugar that could melt at the high
temperature of baking hence increasing the spreadability of the material . In earlier study,
Table 3. Baking properties of biscuit samples
Key a-e: Means with the same superscripts within each row are not significantly different (p≥0.05).
Chemical composition of biscuit samples
The proximate composition of biscuit samples is as shown in Table 4. The moisture content
range was within 3.22-4.58%. Sample T-0 has the highest percentage moisture content of 4.98%
while the least value was recorded for sample T-5 with of value of 3.22%. The observed decrease in
moisture content of biscuit samples as the level of substitution of chicken egg with duck egg increased
could be explained by the fact that duck egg contains less moisture than chicken egg . Moisture
is a favourable sensorial attribute in baked products because it is synonymous with a soft, tender
product though values higher than 10% promote microbial growth . The protein content of the
biscuit samples ranged from 9.4-12.9%. Increase in the levels of duck egg substitution of chicken egg
resulted in an increase in the protein content progressively, which is attributed to the high protein
content of the duck egg. Substitution of 50% duck egg to chicken egg resulted in the highest protein
content of 12.9%. The large size of duck egg gives it a larger yoke to white ratio than chicken egg.
Both egg white and egg yolk in the duck egg contains 3% of more those amino acids than egg yolk
and white of the hen egg. Duck egg white contains by about 50% phenylalanine, about 30%
methionine and by about 24% threonine more than that of the hen egg. Similarly, duck egg yolk
protein contains by 22% methionine and by 13% lysine more than that of the hen egg . The result
implies that the biscuit samples containing duck egg were high in protein content and could be used
as alternative protein source in areas with protein deficiency.
Table 4. Proximate composition of biscuit samples
Key a-f: Means with the same superscripts within each row are not significantly different (p≥0.05)
42 Volume 5
There was no significant difference (p≥0.05) in the fibre content of the samples. This is expected
as chicken egg and duck egg contain virtually no fiber; hence the value reported was derived from
other ingredients in biscuit formulation. The fat content of the biscuit samples ranged from 15.8-
19.2%. The fat content increases with higher levels of duck egg in the formulation. Duck egg contains
higher yolk ratio to egg white, hence it has more fat and cholesterol than chicken egg . More
specifically, the yolk of an egg contains the cholesterol; the white contains none . It has been
reported that high levels of cholesterol in the bloodstream, especially low-density lipoprotein (LDL)
cholesterol, are associated with increased risks of atherosclerosis and its consequences, including
heart attacks and strokes . However, cholesterol in the diet is not the principal factor affecting the
level of cholesterol in the bloodstream. Previous extensive scientific research indicates that the type
and amount of fat in the diet are more important in determining blood cholesterol levels than the
amount of cholesterol in the diet . The main dietary determinant of blood levels of LDL
cholesterol is saturated fat intake . Unlike many other foods that are high in cholesterol, such as
fatty meats and full-fat dairy products, eggs are relatively low in saturated fat and calories. Cholesterol
in the bloodstream comes from two sources: some are synthesized by the body, and some come from
food. In most instances, when dietary cholesterol intake increases, the body compensates by
decreasing its cholesterol production. Conversely, when cholesterol intake decreases, synthesis
increases. The existence of this compensatory mechanism is the reason why changes in dietary
cholesterol intake have only a limited effect on blood cholesterol levels. An analysis of data from a
major United States national nutrition survey showed no relationship between dietary cholesterol
intake and blood cholesterol level and actually found lower blood cholesterol levels in people who
ate eggs frequently than in non-consumers .
There was a significant difference (p≤0.05) in the ash content of the biscuit samples. In case of
biscuit samples containing duck egg, there was increase in ash content with increase in level of
substitution. The carbohydrate content of biscuit samples varied from 62.4% to 68.8%. Carbohydrate
content of the control (T-0) was highest while sample T-5 had the lowest. The result implies that the
biscuits are potential source of carbohydrate. Gross energy content ranged from 397.67kcal/g to
411.85kcal /g in the biscuits samples. The energy values indicate that the biscuits could serve as a
good source of energy for the body.
Mineral composition of biscuit samples
Table 5 shows the amounts of mineral elements in biscuit samples. The results indicated the
range of calcium, magnesium, potassium, phosphorus, iron and zinc to be 1.23-2.22mg/kg, 2.99-
5.50mg/kg, 8.01-12.60mg/kg, 15.20-21.62 mg/kg and 0.31-0.58mg/kg and 0.18-0.36 mg/kg,
respectively. Considering the concentrations of essential major and trace elements, nutrition of the
biscuit samples was positive. It was observed that the concentration of mineral elements in biscuit
samples containing different level of duck egg was higher than of the control, which is coincidental
with the results of ash. The increase in mineral content in the biscuit samples as the level of
substitution of chicken egg with duck egg increases could be due to higher concentrations in duck
egg compare to chicken egg . Duck egg is an excellent source of minerals such calcium,
magnesium, phosphorus and potassium mostly found in the yolk. These macro elements are important
in the diet because of their various functions in the body. In addition, iron and zinc concentrations
were significantly higher in biscuit samples containing different levels of duck egg compared to the
control. The iron in egg yolks, like the iron in meat, is highly bioavailable; egg yolks may, therefore,
be valuable in the diets of individuals who may need more iron, such as infants . Zinc is involved
in well over one hundred different reactions in the body. Some of these reactions help the bodies
construct and maintain DNA, and repair of tissues . It is expected that slight enrichment of zinc
as a result of substitution of chicken egg with duck egg in biscuit production would contribute to the
reduction of diarrhea and pneumonia mortality in children. However, it is worthy to note that the
concentration of these elements in all the blends is quite low though the optimum dietary level for the
individual elements required for humans is very difficult to clarify because of each variation of
Sustainable Food Production Vol. 5 43
Table 5. Mineral composition of biscuit samples (mg/kg)
Key a-f: Means with the same superscripts within each row are not significantly different (p≥0.05)
Sensory quality of biscuit samples
Mean score for sensory evaluation of biscuit given in Fig. 1. The result revealed significant
differences (p≤0.05) between treatments for sensory attributes like colour, taste, flavour, crunchiness,
texture, sweetness and overall acceptability. Sensory rating of biscuit for colour shows that sample
T-0 was rated highest (4.75) while sample T-1 was rated lowest (4.00). Colour is a very important
parameter in judging properly baked biscuits that not only reflect the suitable raw material used for
the preparation but also provides information about the formulation and quality of the product .
Darker colour was noted in biscuit samples containing varying level of chicken egg and duck egg
compared to the control (sample T-0). The change in colour may be due to the non-enzymatic reaction
between reducing sugar molecules and higher level of protein in duck egg. In the taste attribute, the
result showed that the biscuit sample containing 50% duck egg had the highest mean score of 4.55.
This was closely followed by that of 40% and 20% substitutions with duck egg with mean scores of
4.30 and 4.25 respectively. Duck egg has much larger yolk than chicken egg and consequently much
higher fat content which gives a rich taste to biscuits. In terms of flavour, there was no significant
difference (p≥0.05) among the samples. The observation is in accordance with the finding of
Niewiarowicz et al.  that revealed no flavour differences between hard-boiled Peking duck and
"Astra S" hen eggs.
Figure 1. Sensory mean scores of biscuit samples containing varying levels of duck egg
Egg yolk is rich in fat and lecithin and these components enhance the flavour and eating quality
of biscuit. Panellists accepted the crunchiness of the biscuit samples up to 50% substitution with a
mean value of 5.84. From the result, the crispness of the biscuits increased with increase in the level
of duck egg in the formulation. Considering the texture of the biscuits, samples containing different
levels of duck egg were highly rated compared to the control. Duck egg impacts a creamier, richer
44 Volume 5
texture to biscuits due to the higher fat content. Fats also tend to inhibit the leaving action of
carbondioxide diffusion in the dough during baking which subsequently results in product with a
softer texture. Moreover, this expresses the ability of more egg white in duck egg which helps
incorporate air in dough during mixing that affects the textural properties . In terms of sweetness,
there was no significant difference (p≥0.05) among the samples. However, the overall acceptability
of biscuits containing different levels of duck eggs was rated higher than that of the control.
Generally, the observed differences in consumer’s preference and overall acceptability of the
biscuit samples could be explained by the variation in the physical, chemical properties of ingredients
in the various formulations. It is worthy to note that in the baking industry in particular, eggs supply
unique and extensive concentration of functional contributions which is not likely to be exhibited in
egg substitute as an ingredient. Eggs contribute high nutritional value and multifunctional properties
that make researchers to often admit that the use of egg replacer is not a match to egg in terms of
This present study shows that there is potential for different combinations of duck egg to replace
chicken egg in biscuit production. Substitution of duck egg induces major changes in the physical
properties of the biscuits. Similarly, biscuit samples of adequate nutritional and sensorial qualities
were produced from the blends. The substitution of chicken egg with duck egg at a level of up to 40%
produces biscuit without any negative effects in quality attributes and reasonable acceptance, offering
a promising, nutritious and healthy alternative to consumers.
The authors sincerely acknowledge the support of the staff of Food Science and Technology,
Bowen University, Osun State, Nigeria.
Conflict of Interest
The authors declare that there is no conflict of interest.
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