Texture and Sensory Qualities of Steam Cake Containing Soy Protein Isolate

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Texture and Sensory Qualities of Steam Cake Containing Soy Protein Isolate
C. Channgern and O. Suriyaphan
Department of Food Science, Faculty of Science, Burapha University, Chonburi 20130, Thailand
Abstract
Wheat flour (11.69% protein) containing 3%, 6%, 9%, 12% and 18% of Soy Protein Isolate (SPI,
Profam974®) were used to make steam cakes. Each set of obtained steam cakes was determined its color,
texture and sensory qualities compared to the steam cake without SPI (control). It was found that the
additional SPI in wheat flour significantly increased redness (a*), yel owness (b*) while reduced lightness (L*)
of steam cakes. Texture analysis also indicated that the firmness of steam cake significantly increased by the
amount of SPI (p<0.05). By performing quantitative descriptive analysis (QDA, n=10, 15 cm line scale), 13
at ributes were selected to demonstrate the ef ect of SPI on sensory qualities of steam cakes. Steam cake
containing higher amount SPI possessed the higher intensities of yel owness, starchy, beany, lumpy and
astringency. Additional y, the intensities of smoothness, jasmine flavor, cooked white egg, sweetness, softness,
crumbliness and symmetry of steam cakes with SPI were gradual y lower by amount of SPI. Based on overal
liking (9-point hedonic scale), the steam cake containing 9% SPI was not dif erent from the control (without
SPI) and was accepted by panel.
Key words: Soy Protein Isolate, Steam cake, Quantitative Descriptive Analysis, Texture analysis

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Introduction
Soy protein has been used as nutritional and functional food ingredients in every food category
available to the consumer. Soy protein isolate (SPI) is the most highly refined soy protein products
commercial y available. General y, SPI contains not less than 90% protein on a moisture free basis. To
present, SPI is the most wel accepted ingredient of healthy products as the major source of protein (Endres,
2001). Soybean is native to Eastern Asia, playing a significant nutritional role in that region as does wheat in
the United States. Therefore, it can be concluded that Asian people are more familiar with soy or beany flavor
in soy based products than westerner. However, addition of soy protein normal y causes adverse effects on
acceptance of foods according to the alterations of sensory qualities. Therefore, the bet er understanding of
ef ect of SPI on pasting properties of wheat flour containing SPI and qualities of steam cake would help local
food industries to develop high qualities of steam cake containing SPI and related products. The objective was
to investigate textural and sensory qualities of steam cake containing SPI.
Experimental
Material
Wheat flour (11.69% protein) was purchased from United Flour Mil s Company Ltd (Thailand). Soy
protein isolate (Pro-Fam®974, 87.79% protein) was gifted from Archer Daniels Midland Company (USA.).
Pasteurized liquid egg (13.68% protein) was from Bangkok Produces Company (Thailand). SP was a
commercial emulsifier distributed by American Bakery Company (Thailand). Al other ingredients for making
steam cake were local y purchased in local market. Al chemicals used in the analysis of steam cake were AR
grade or equivalent.
Method
Preparation of Steam cake or Pui-Phai
Pasteurized liquid egg (100 g) was wel whipped with sugar (175 g), water (100g) and SP (10 g) until
obtained thick cream prior to gradual y add wheat flour (200 g) and baking powder (3 g). Unsweetened
condensed milk (50 mL), lime juice (5 g), and jasmine flavoring (1.4 g) were added to obtain cake bat er.
Thirty grams of bat er were place in each paper cup and then subjected to steam for 20 mins. Steam cakes
were kept in plastic box until analysis. For steam cake containing SPI, SPI was directly added to wheat flour
and twice sieved prior to mix with other ingredients.
Color measurement

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Color of bat er and steam cake were determined by measuring the Tri-stimulus values using Handy
Colorimeter (Garner, Germany). The CIE color value included L*(lightness), a*(redness) and b*(yel owness).
Texture analysis

Consistency of steam cake bat er and firmness of steam cake was determined using TA.XT2 texture
analyzer (Stable Micro System, UK). For consistency measurement, the equipment was equipped with Back
Extrusion Rig (A/BE30) and operated with fol owing parameters; Option=Return to start; Distance=25%. For
firmness test, the selected probe was 35 mm cylinder (P/35). The instrument was operated with fol owing
parameter; Option=Hold until time; Strain=25% and Time=60 s. In both tests, Pre-Test Speed=1.0 mm/s; Test
Speed=1.0 mm/s; Post-Test Speed=1.0 mm/s. Results were the average of three triplicate determinations.
Sensory Evaluation
Acceptability test

The acceptability on color, flavor, taste, softness, and overal liking of the steam cake with and
without SPI was evaluated by 20 panelists. Each panelist was served with 6 samples (control and steam cake
with 3%, 6% 9% 12%and 18% SPI) in a randomized serving sequence. The 9-point hedonic scale was used in
this study, that is, 9 = extremely like, 5 = neither like nor dislike, and 1= extremely like.
Quantitative Descriptive Analysis (QDA)

The sensory profiles of steam cakes with and without SPI were evaluated by trained panelist (n=10).
Descriptors, description and references were constructed by panel. The descriptors included yel owness,
symmetry, fineness, jasmine odor, cooked white egg odor, cooked white egg flavor, cooked starch, beany
flavor, sweetness, softness, crumbliness, and astringency. The structured 15-cm line scale (0= none, 15= high)
was used in scoring the intensity of each at ribute.
Statistical analysis

For analysis of variance (ANOVA) in color, consistency, firmness and QDA data, the experiment
design was completely randomized (CRD). For each treatment, three determinations were performed and the
mean values were calculated. Duncan s multiple range test was used to determine the significances within
treatments. Values were considered significant dif erent when p<0.05. In acceptability test, the experimental
design was randomized completely block design (RCBD) with n=20. Duncan s multiple range test was used
to determine the significances within treatments. Values were considered significant dif erent when p<0.05.

Results and Discussion

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Colorimetric data demonstrated the additional SPI in wheat flour slur y caused the adverse ef ect
toward its lightness (Table 1). In addition, steam cake slur y possessed higher redness and yel owness by the
increase amount of added SPI (p<0.05). Furthermore, steam cake with SPI possessed lower lightness (Table
2). Commercial SPI possessed light yel ow by its nature (Endres, 2001). These negative ef ects on
appearance of food products containing SPI were usual y found in many studies (Drake and other, 2000;
Pukkalanan, and Suriyaphan, 2003, Klingadung and Suriyaphan, 2003; Sripanormwan and Suriyaphan, 2005).
Table 1: Mean value of color value of steam cake slurry with and without SPI
% SPI
Lightness (L*) Redness (a*) Yel owness (b*)
0
89.01±2.22c
2.03±0.56a
18.14±2.26a
3
88.10±0.56bc 2.26±0.79a
19.45±1.51ab
6
87.15±0.55bc 2.63±0.06ab
19.79±1.89ab
9
86.79±0.99bc 2.99±0.16abc
20.42±11.65b
12
85.21±2.16ab 3.40±0.11bc
20.75±1.32b
18
83.81±1.07a
3.71±0.08c
22.13±0.13c
abc Mean values in a column with different let ers are significantly dif erent (p<0.05)

Table 2: Mean value of color value steam cake with and without SPI
% SPI
Lightness (L*) Redness (a*) Yel owness (b*)
0
85.44±0.05d
2.77±0.03a
23.45±0.67 a
3
84.19± 0.31c 2.91±0.06 ab
24.28±0.42 ab
6
83.88±0.25c 3.29±0.12bc
24.44±0.72 ab
9
82.89±0.06b 3.46±0.23 cd
25.35±0.20 bc
12
82.23±0.48ab
3.77±0.23de
25.56±0.83 bc
18
81.30±0.69a
4.07±0.16e
26.00±0.00 c
abc Mean values in a column with different let ers are significantly dif erent (p<0.05)


As expected, SPI significantly contributed consistency of steam cake slur y (Figure 1). Natural y, SPI formed
protein gel via water adsorption during re-hydration. The increase of consistency of steam cake slur y was
considered as undesirable at ribute for processing since it inhibited the expansion of steam cakes during

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steaming resulting low specific volume and high firmness (Figure 2). Appearances of al steam cakes with and
with SPI were shown in Figure 3. Coloring (0.05 g) was added in al formulations to obtain good images of
steam cakes.

25.0
140
Yel owness
Consistency
120
20.0
100
15.0
80
10.0
Y
e
l
o
w
n
e
s
s

(
b
*
)
60
C
o
n
s
i
s
t
e
n
c
y

(
g
)
40
5.0
20
0.0
0
0
3
6
9
12
18
%SPI

Figure 1 : Yellowness (b*) and Consistency of steam cake slurry with and without SPI

800
2.6
Firmness
Specific Volume
700
2.5
600
2.4 )/gL
500
2.3 (me
n
e
s
s

(
g
)
m
400
l
u
o
F
i
r
m
2.2 Vific
300
c
e

p
2.1 S
200
2
100
0
1.9
0
3
6
9
12
18
% SPI

Figure 2: Firmness and Specific volume of steam cakes with and without SPI

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6% SPI
9% SPI
Control
12% SPI
18% SPI


Figure 3: Comparison of steam cakes with and without SPI (Control)

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6% SPI
9% SPI
12% SPI
18% SPI
Control

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Considering sensory qualities of steam cake containing SPI, the panel (n=20) concluded that SPI
significantly reduced liking on color, flavor, taste, softness and overal liking (Figure 4) (p<0.05). Based on
overal liking, it could be concluded that the maximum amount of additional SPI in steam cake was 9%. By
performing QDA, the sensory profiles of steam cake with and without SPI, the panel (n=10) was able to
distinguish the undesirable at ributes in steam cake containing SPI. In addition, SPI contributed higher
astringency, lumpiness, crumbliness and beany flavor resulting lower acceptability on steam cake (Figure 5)


9
8
7
6
M
e
5
a
n

S
c
4
o
r
e
3
2
1
0%
0
3% 6%
Ov
9%
S
e
T
oft
r
n
al -
12%
F
a
e
li
%
l
s
k
a
te
s
ing
SPI
18%
C

o
v
lo
o
r
r

Figure 4 : Mean values of liking scores of steam cakes with and without SPI
(1 = extremely dislike, 5 = neither like nor dislike, 9 = extremely like)

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Yel owness
14
Astringency
Symmestry
12
10
Lumpiness
Fineness
8
6
4
2
Crumbliness
Jasmine odor
0
Softness
Cooked white egg odor
Sweetness
Cooked white egg flavor
Beany flavor
Cooked starch
0% SPI
6% SPI
12%SPI


Figure 5 : Sensory profiles of steam cakes without SPI (•) compared to steam cakes containing 6% SPI
(?) , and 12% SPI ( )

Yel owness
14
Astringency
Symmestry
12
10
Lumpiness
Fineness
8
6
4
Crumbliness
2
Jasmine odor
0
Softness
Cooked white egg odor
Sweetness
Cooked white egg flavor
Beany flavor
Cooked starch
0% SPI
9% SPI
18% SPI

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Figure 5 (cont.) : Sensory profiles of steam cakes without SPI (•) compared to steam cakes containing 9% SPI
(?) , and 18% SPI ( )

Yel owness
14
Astringency
Symmestry
12
10
Lumpiness
Fineness
8
6
4
Crumbliness
0% SPI
2
Jasmine odor
0
3% SPI
6%SPI
Softness
Cooked white egg odor
9%SPI
12%SPI
Sweetness
Cooked white egg flavor
18%SPI
Beany flavor
Cooked starch

Figure 5 : Sensory profiles of steam cakes without SPI (•) compared to steam cakes containing different
amount of SPI
Conclusion
The presence of SPI significantly affected the texture and sensory properties of steam cake. SPI
imparted yel owness and redness of steam cake slurry while increased apparent consistency. Steam cake
containing SPI possessed higher firmness resulting in low overal liking. It could be concluded that the
additional amount of SPI was limited due to the changes of color, clarity, flavor and texture in the final
products. The maximum amount of added SPI in steam cake was not greater than 9% by weight of starch.
References
Drake, M.D.; Chen, X.Q.; Tamarapu, S.; and Leenanon, B. 2000. Soy Protein Fortification Affects Sensory,
Chemical, and Microbiological Properties of Dairy Yogurts. Journal of Food Science. 65 (7): 1244-
1247
ChimChin, D. and Suriyaphan, O. 2003. Fortification of Instant Fried Japanese Noodles with Defat ed
Pumpkin Seed Kernel Meal. In The 5th Agro-Industrial Conference; ThaiFex & ThaiMex 2003.

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