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Effects on Physical and Functional Properties of Dried Whole Eggs of
Cassava (Manihot Esculenta Crantz) Starch Additive and Corn Syrup
Additive
Joanna Tess Masilungan-Manuel 1
, Christa Loraine G. Sino 1
, Aiza V. Jarin 1 and Flordeliza C. De
Vera 2
1 Chemical Engineering Graduates, Mapua
Institute of Technology, Muralla St., Intramuros, Manila
Philippines
2 School of Chemistry and Chemical Engineering, Mapua
Institute of Technology
Abstract. Primarily eggs were marketed as shelled eggs, but due to breakages and spoilage, better storage
techniques were needed. Oven drying is one of the preservation techniques used to address this concern.
Powdered egg is a convenient alternative to fresh egg because it can be stored for a longer period. Usually,
carbohydrates such as corn syrup are used as additive to powdered egg to increase its shelf-life. Literatures
indicate that tapioca starch has more carbohydrate content than corn syrup. Thus, a comparative analysis
between tapioca starch and corn syrup as additive for powdered egg was conducted. Physical and functional
properties of the product showed that 20% tapioca starch is the optimal amount to be added to liquid eggs
prior to drying. In addition, drying curve and sorption isotherm implies that tapioca starch facilitates shorter
drying time and displays lower value of moisture content after drying, making it shelf-life more stable.
Keywords: drying, dried eggs, tapioca starch, powdered eggs, batch drying, oven drying
1. Introduction
For many years, eggs were marketed primarily as shell eggs, but in recent years, egg consumption in the
form of egg products had increased [1]. Drying is a successful way of preserving eggs, and the egg drying
industry has been developed for several years. Most of the food industry preferred dried eggs over fresh egg
because of the following advantages: (1) they can be stored at low cost under dry storage or refrigeration
with reduced space treatment, (2) transportation cost is low because water has been removed, (3) they are
easy and clean to use, and (4) they can be used in and are necessary for many convenience foods [2].
Although many problems regarding egg products have been resolved, there are other factors that need to
be taken into consideration. Among of these problems are the improvement of the foaming properties of the
whole egg and the increase in the shelf-life of the dried egg product. Literature indicates that the specific
gravity is an indirect measure of the volume of foam and a low value of specific gravity indicates that the
foam will produce larger volume [2].
Powdered eggs are usually dried u and would contain 14% initial moisture.
Note that if higher temperatures are used, the egg will be cooked instead of being dried [3]. By nature, we
know that the equilibrium moisture content (EMC) decreases as the egg is dried because water is removed.
However, based from the findings later presented, it had been shown that the EMC of the final product
increases as the relative humidity of the surrounding increases, thus, making the powdered egg prone to
degradation. One way to prevent this type of phenomena is through the addition of certain carbohydrate
source to the liquid egg mixture before drying [4]. The amount of protection given by the carbohydrate
Corresponding author. Tel.: + 02-801-2486.
E-mail address: [email protected].
2014 4th International Conference on Biotechnology and Environment Management IPCBEE vol.75 (2014) © (2014) IACSIT Press, Singapore
DOI: 10.7763/IPCBEE. 2014. V75. 8
47
depends on the percentage of the carbohydrate used, hence, the higher the level of carbohydrates, the greater
the protection of the egg from degradation [5]. Studies also pointed out that the moisture content of the
powder egg should be below 5% by weight in order to preserve its flavor and nutrition [6].
Corn syrup is the common additive used because it contains sufficient carbohydrate that can prevent the
powder egg from degrading. However, corn syrup is hygroscopic and eventually accumulates moisture over
some period of time. Since the Philippines is abundant with agricultural products like root crops that are rich
in carbohydrates, the researchers look for an alternative for corn syrup. Cassava (Manihot Esculenta Crantz)
starch, commercially termed as Tapioca starch, is copious in the Philippines and it is extensively cultivated
as an annual crop in tropical and subtropical regions for its edible starchy tuberous root. It can be used as a
substitute for corn syrup because it contains higher carbohydrate content, and it is cheaper and readily
available.
2. Preparation of the Mixture
For the standard mixture, 300g of beaten chicken eggs were prepared. Corn syrup corresponding to 10%
of the weight of the eggs was added. It was mixed until it became homogeneous. On the other hand, three
hundred grams beaten chicken eggs was prepared for the test mixture. Tapioca starch corresponding to 5% of
the weight of the eggs was added to the prepared test mixture. Amount of water that was added to the test
mixture is 7.5 mL. The same procedure was done for 10% with 15 mL water, 15% with 22.5 mL water, 20%
with 30 mL water, and 25% with 45 mL water. Three trials for each mixture were conducted.
3. Characterization of the Mixture
3.1. Density
The density of the mixture was determined using the pycnometer. First, the weight of the dried empty
pycnometer was determined. A known volume of the sample was placed inside the pycnometer and the total
weight was measured using the analytical balance. After this, the weight of the sample was calculated by
subtracting their weights. Since the volume and the weight of the sample were already known, the density of
the fluid mixture was determined.
3.2. Specific gravity
The specific gravity was evaluated in :
. . ss
w
S G
(1)
where S.G.s h p c f c y f h ub c , ρs h y f h ub c ρw is the density of
water at 4°C, 1 atm.
4. Drying of the Sample
The mixture was spread in a size 20 mesh screen using a brush. The screen was placed on the top of the
tray. The trays containing the samples were placed inside the (WTB binder 78532 Tuttlingen, Germany)
oven w h mp u ˚ . Total drying time was fixed at 30 minutes.
5. Drying Rate Curve Determination
The sample was spread inside a tarred 0.0016m2 muffin pad and placed on a pan. The pan was put inside
the oven and for every two minutes, each pad was removed and weighed. This was done until the pads
achieved constant weight which indicated that the drying time was complete. The mass of the dry sample
was calculated using :
t dd
t
mm
m
(2)
where dm is the mass of the dry sample is, t sm is the mass of the tray with the dry sample and tm is the
mass of the tray. After the mass of the dried sample was determined, the mass of the water removed from the
sample was computed:
48
t ww
t d
mm
m
(3)
where wm is the mass of water and t wm is the mass of the tray with wet sample. Lastly, the free moisture
content, X, was obtained using .
w
d
mX
m (4)
The free moisture content was plotted having the free moisture content as the ordinate and the time as the
abscissa. The drying rate was obtained using .
sL dXR
A dt
(5)
where R is the drying rate in 2
2/H Og hr m ; Ls is the mass of dry sample used in grams; A is the surface area for
drying, in m2; X is the free moisture content in
2/H O dryg g ; and dX/dt is the time dependent rate of change of
the free moisture content. Note that t is the drying time in hours.
6. Sorption Study
After the best ratio of tapioca starch was determined, a sorption study was conducted for both the dried
eggs with corn syrup and with tapioca starch. Three sets of trials were performed using fifteen (15) crucibles
for each trial of the two additives. The weights of each crucible were noted before placing about one gram of
sample inside. The crucible cover was placed upside down to hold the cotton on the top of the crucible cover.
This is done to prevent the formation of molds in the sample. One hundred milligram of sulfuric acid and
One hundred milligram of water were used for preparing 50%, 60%, 70%, 80% and 90% by weight solutions.
Each of the prepared solutions was transferred in desiccators. Three crucibles corresponding to three trials
for each of the sample were placed inside a desiccator with the sulfuric acid solution and were allowed to
equilibrate. After equilibration, each crucible was weighed using the analytical balance. Two to three drops
of dimethyl chloride (DMC) were applied to the cotton on top of each crucible every after weighing to avoid
the formation of molds on the sample. Weighing was done every 24 hours for two weeks to monitor if
equilibrium was attained. The equilibrium moisture content was calculated using the :
( ) ( )
(1 )
f i i i
i i
W W M WEMC
W M
(6)
where EMC is the equilibrium moisture content; Wf is the final weight of sample after equilibrium at a
specific relative humidity/acid concentration; Wi is the initial weight of the sample in the PEC (Proximity
Equilibrium Cell) and Mi is the initial moisture content fraction. The initial moisture content fraction was
determined by drying approximately one gram of the powdered sample for 24 hours. The difference of the
initial and the final weight is the initial moisture content fraction.
It had been shown that the EMC of the final product increases as the relative humidity of the surrounding
increases as presented in Table 1.
T bl 1: Equ l b um M u f Wh l E S l ˚ R l Hum y
% Relative humidity Equilibrium Moisture Content (EMC) at 60 degree Celsius
10 1.8
20 2.6
30 3.4
40 4.2 50 5.4
7. Results and Discussion
The research performed was divided into three major parts. The first part was the characterization of the
physical and functional properties of whole egg. The second part was the establishment of a drying curve for
dried whole egg and the last part was the sorption study on the dried product.
7.1. Characterization of the physical and functional properties
49
Results of the two-way test anova without replication at 95% level of significance show that the data
obtained for the physical and functional properties of dried whole egg has no statistical importance (F
critical > F). This means that the values were comparable. Based on the results presented in Table 2, dried
eggs with 20% tapioca starch had the nearest characteristics to that of dried egg with 15% corn syrup. The
specific gravity of the dried egg with 20% tapioca starch was 1.0763; this was comparable to the dried egg
with 15% corn syrup having a specific gravity of 1.0688. The same analysis was done for density, wherein
dried egg with 20% tapioca starch was 1071.37 kg/m3 while dried egg with 15% corn syrup was 1063.98
kg/m3. From the data obtained, the specific gravity and the density of dried egg with 20% tapioca starch has
the closest value among other percentages of tapioca starch added. Also, since the foaming power is directly
proportional with the specific gravity after drying, this specifies that dried egg with 20% tapioca is the
optimal amount of additive needed to increase its foam stability.
Table 2: Summary of Results
Corn Syrup Tapioca Starch
15% 5% 10% 15% 20% 25%
Specific Gravity 1.0688 1.0469 1.0343 1.0376 1.0763 1.0888
Density (kg-m-3) 1063.98 1042.20 1029.57 1032.93 1071.37 1083.90
Color Dark Yellow Light
Yellow Light Yellow Light Yellow Light Yellow Light Yellow
Flavor Egg like Egg like Egg like Egg like Egg like Egg like
7.2. Drying rate curve
Fig. 1 shows the comparison of the drying rate curve for both dried egg with 20% tapioca starch and 15%
corn syrup. It can be noted that points A’’ B qu h u u lly f l u y
adjustment period and is often ignore in the analysis of times of drying. On the other hand, the constant rate
period for both the corn syrup and tapioca starch are shown in points B to C. As seen in this period, the
drying time of dried whole egg with tapioca starch is shorter than the corn syrup. This implies that dried
whole egg with corn syrup contains more moisture than the dried whole egg with tapioca starch and this is
supported by the fact that corn syrup is a hygroscopic substance.
Fig. 1: Drying rate curve of whole eggs with additives
7.3. Sorption study
In Fig. 2, the lower and upper lines show the sorption isotherm for both the dried eggs with tapioca
starch and corn syrup. The isotherm curve of the powdered sample with 20% tapioca starch is almost similar
to the isotherm of the 15% corn syrup. As mentioned earlier, in order for the food to be stable and less prone
to degradation, its EMC content should be less than 5% and should not increase at high relative humidity of
the surrounding. Based from the figure presented, both powdered egg maintains its EMC as the relative
humidity of the surrounding increases, indicating that both carbohydrate source can improve the shelf-life of
the product. However, the figure presented also shows that the corn syrup has a higher EMC compared to
tapioca starch, thus making tapioca starch a better additive to powder egg than the corn syrup.
50
Fig. 2: Sorption Isotherm Curve of whole eggs with additives
8. Conclusion
The tests on physical and functional properties of the product indicate that 20% tapioca starch is the
optimal amount to be added to whole eggs prior to drying. The functional and physical properties of this
product are comparable to the product with 15% corn syrup. Drying rate curve of the two samples implies
that tapioca starch facilitates shorter drying time compared to corn syrup and the sorption isotherm trend of
sample with tapioca is comparable to sample with corn syrup indicating that tapioca starch can be a good
carbohydrate source substitute in producing powder eggs.
9. References
[1] Brennan, R.F., Food Technology. Chapter 2, Types of dryer in the food industry, 2005. pp. 65-74.
[2] Barmore, M.A., Home Economics. Chapter 48, The influence of chemical and physical properties factors on dried
eggs. 2000. 420-421.
[3] Bergquist, D.H., Food Technology. Chapter 8, Method of preparing powdered eggs. 2001.
[4] Chickner, F.H., Food Science. Chapter 15, Process of determining egg powder. 2005.
[5] Slosberg, H.M., Poultry Science. Chapter 27, Some factors affecting the functional properties of liquid whole eggs.
2002.
[6] Schultz, J.R. and R.H. Forsythe, Food Science. Chapter 23, Carbohydrates effects on the performance of the
whole egg solid. 2006. 507-513.
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