SENSORY EVALUATION OF GOAT MILK CHEESE UNDER DIFFERENT FREEZING CONDITIONS


   
  

250 

 

Journal homepage: www.fia.usv.ro/fiajournal 

Journal of Faculty of Food Engineering,  

Ştefan cel Mare University of Suceava, Romania  

Volume XVI, Issue 4 - 2017, pag. 250 -  255 

 

 
 

SUPPLEMENTATION OF WHEAT FLOUR WITH SOY FLOUR, SENSORY AND 

PHYSICO-CHEMICAL EVALUATION OF FORTIFIED BISCUITS 

Flavia POP
1*, Zorica VOȘGAN1, Lucia MIHALESCU1 

 
1Department of Chemistry and Biology, Technical University of Cluj-Napoca, North University Center of Baia 

Mare, 76A Victoriei str., 430122, Baia Mare, Romania,  
*Corresponding author: flavia_maries@yahoo.com 

Received 23th October 2017, accepted 18th December 2017 

 
Abstract: The research was conducted in order to evaluate the physico-chemical and quality 
characteristics of biscuits fortified with soy flour that could be used as a protein supplemented food. 

Wheat flour has been replaced at different levels with soy flour that were 30% (R4), 20% (R3), 10% 

(R2) and without soy flour, control (R1). The fat content of control was 16.36% and increased to 

19.4% in the case of 30% soy flour formulation that could be due to the increase in the proportion of 
soy flour in the flour blend. The highest mineral content was obtained in R4 (1.98%) and the lowest in 

R1 (0.552%), soy flour brought a significant contribution to mineral substances, and the ash content 

increased gradually with the increase in the percentage of soy flour. From the sensory evaluation, the 
biscuits with 10 and 20% soy flour addition presented similar characteristics, biscuits supplemented 

with up to 20% soy flour have shown superior nutritional characteristics as compared to wheat flour 

biscuits. 

 
Keywords: soy flour, biscuits, fat content, saturation capacity, sensory evaluation. 

 

1. Introduction 
 

Soy is particularly rich in lecithin, a very 

valuable emulsifier, in proteins and 

polyunsaturated fatty acids. The water 

absorption capacity of soy flour is much 

higher than that of wheat flour. In 

combination with wheat flour, soy flour is 

used for the preparation of bread or various 

pastry products. Soy flour does not contain 

cholesterol, is ideal for people who are 

lactose intolerant, does not contain gluten, 

is rich in fat but poor in starch. Soy flour 

contains vitamins B, vitamin E, 

magnesium, phosphorus and calcium [1, 

2]. 

Cracked biscuits are prepared from flour 

with medium or low gluten, because a high 

gluten content leads to hard biscuits.To 

reduce the high gluten protein content of a 

flour, it can be used wheat, potato or corn 

starch, which reduces the elasticity and 

increases the plasticity of the dough. Due 

to its complex composition, the biscuits 

dough is more difficult to prepare 

compared to the dough intended for bread 

preparation, because additional additives 

reduce the moisture capacity of the flour 

and gluten elasticity [3-6]. 

The dough for sugary biscuits involves an 

initial mixing of powdered sugar with fats, 

until it reaches an aliphous consistency 

without any roughness. The cream is 

mixed with sugars, eggs and essences 

homogenised in advance, and finally the 

flour is added. After homogenization the 

leavening agents are added and the 

kneading continues for 20-30 minutes. The 

increasing of the mixture temperature to an 

optimal value, favors the fluidization of 

certain components, the ability to hydrate 

the flour and reduce kneading time. 

Although in dough with higher humidity 

the development of the gluten network is 

http://www.fia.usv.ro/fiajournal


Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 

Volume XVI, Issue 4  – 2017 

 
Flavia POP, Zorica VOȘGAN, Lucia MIHALESCU, Supplementation of wheat flour with soy flour, sensory and 
physicochemical evaluation of fortified biscuits Food and Environment Safety, Volume XVI, Issue 4 – 2017, pag. 250 – 255   

251 
 

 

faster, it is not recommended to use a very 

wet dough, because it occurs a negative 

influences on the texture and shape of 

biscuits. After kneading the dough is left at 

rest, when the dough is matured, by 

repairing gluten threads damaged at 

kneading, that leads to the improvement of 

the rheological characteristics of the dough 

[7-9]. 

During the rest, the decomposition of the 

leavening agents begins, under the action 

of component acidity; the resulting gases 

loosen the dough and diminish its 

consistency. Inappropriate storage or low 

humidity, leads to defective biscuits such 

as absence of volume and porosity, 

ruptures, surface blisters. Also, if the 

thickness of the dough layers is too high, 

the dough layers in the lower part are 

heated, chemical decomposition is very 

fast and they break apart completely during 

the resting phase. The formed gases will be 

largely eliminated at rolling and the final 

products will have low porosity and 

volume. The cooling of biscuits should be 

done as soon as possible, to strength the 

structure of the product, making it more 

resistant [10-12]. 

The objective of the study was to fortify 

wheat flour with soy flour at different 

levels that were 30% (R4), 20% (R3), 10% 

(R2) and without soy flour as control (R1) 

and to study their effects on the biscuits 

quality. To assess the quality of biscuits 

the following parameters were determined: 

fat content, alkalinity, determination of 

total ash, saturation capacity, acidity and 

moisture content during storage, as well as 

sensory analysis. 

 

2. Materials and methods  

 

Materials 

Wheat flour was replace with soy flour in 

three proportions 30% (R4), 20% (R3) and 

10% (R2) respectively, whereas R1 was 

kept as control (without soy flour).  

Table 1.  

Formulation of the biscuits 

 

The fineness or size of the flour particles 

are of particular importance because 

influences the rate of colloidal and 

biochemical processes and the baking 

characteristics of the dough. 

Wheat flour contains 12% proteins, 70% 

carbohydrates, 2% lipids, 14% water, as 

well as mineral substances, vitamins and 

pigments [4]. 

 

Physicochemical examination 

Acidity is based on the extraction of the 

biscuits acids and their titration with 

sodium hydroxide 0.1 N, using 

phenolphthaleine, as an indicator. Acidity 

was expressed in mL of NaOH 0.1 mol/L 

solution by 100 g of biscuits [13]. 

Fat content was determined by Soxhlet 

method witch consisted of extracting the 

fat from the analyzed sample with ethyl 

ether. Determination of moisture content is 

based on drying of a sample with known 

initial mass to a constant mass. Alkalinity 

determination is based on the titration of 

the alkaline substances extracted from the 

product with HCl solution in the presence 

of blue-bromo-thymol. The alkalinity of 

pastries was expressed in degrees. Degrees 

of alkalinity mean the number of milliliters 

of acid, normal solution, used to neutralize 

the alkalinity from 100 g of a product and 

based on dry matter. Determination of total 

ash is based on the calcination of a known 

mass of product up to constant weight [13]. 

Saturation capacity consists in weighing of 

one or two biscuits that are placed in a pot 

Sam

ples 

Wheat 

flour 

(%) 

Soy 

flour 

(%) 

Sugar 

(g) 

Butter 

(g) 

Sodium 

bicarbon

ate (g) 

R1  100 0 100 100 1.0 

R2 90 10 100 100 1.0 

R3 80 20 100 100 1.0 

R4 70 30 100 100 1.0 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 

Volume XVI, Issue 4  – 2017 

 
Flavia POP, Zorica VOȘGAN, Lucia MIHALESCU, Supplementation of wheat flour with soy flour, sensory and 
physicochemical evaluation of fortified biscuits Food and Environment Safety, Volume XVI, Issue 4 – 2017, pag. 250 – 255   

252 
 

 

of water and allowed to soak for 15-20 

minutes, and then are weighed again. 

Determination of elasticity is based on the 

application of an known external force on 

the dough of known initial length and 

tracking its response. 

To assess the normal taste of biscuits we 

used the descriptive sensory analysis, 

which is an ideal technique to identify 

flavors in a product and to distinguish the 

products between them, using tasters 

familiar with methods of scoring and 

sensory language. 

Sensory analysis was performed on a 

sample of 10 trained panelist, aged 

between 20 and 55 years, according to the 

method described by Farzana and 

Mohajan, [14].  

Values of different parameters were 

expressed as the mean ± standard 

deviation. Significant differences between 

samples were tested by Student’s t-test. 

 

3. Results and discussion 
 

Dough acidity increased directly 

proportional with the increase of soy flour 

content in the biscuits formulatios. 

According to Farzana and Mohajan, soy 

flour has a 24.9% fat content in the 

nutritional composition, and brings a 

significant contribution of fatty acids to 

biscuit dough, and it represents a source of 

linoleic and linolenic acids that are not 

produced by the body [14].  

The dough lost from elasticity directly 

proportional with the increase of soy flour 

and the reduction in gluten content. 

The fat content of control biscuits was 

16.36% and increased to 19.4% in the case 

of 30% soy flour formulation (Table 2).  

The increase in fat content is in agreement 

with several studies [7, 9, 10]. The increase 

in the present study could be explained as 

soy flour is considered as an edible oil 

source, containing a higher percentage of 

fat than wheat flour. Farzana and Mohajan 

reported that the fat content of soy flour is 

between 20-24%, the white wheat flour has 

a 0.9-1.1% content and most of them are 

unsaturated fatty acids. The trend of 

increase in fat content could be due to the 

increase in the proportion of soy flour in 

the flour blend [14]. The highest mineral 

content was determined for R4 (1.98%) 

and the lowest for R1 (0.552), soy flour 

brought a significant contribution to 

mineral substances. The data showed that 

the ash content gradually increased with 

the increase in the percentage of soy flour, 

results which are in agreement with the 

findings of Ayo et al., and Siddiqui et al., 

on the supplementation of soy flour for the 

preparation of biscuits [15, 16]. 

Acidity presented an increasing trend 

during four weeks storage, due to the 

hydrolysis processes occurring in the fat 

formulation. Biscuits presented a higher 

acidity than the dough, due to the amount 

of carbon dioxide resulted from thermal 

decomposition of chemical agents. A more 

pronounced increase in acidity was 

recorded for R3 and R4 (Fig. 1). 

In the present study, the highest moisture 

content was determined for wheat flour 

biscuits (3.6%), and the content gradually 

decreased to 2.07% for biscuits 

supllemented with 30% soy flour. The data 

showed that moisture decreased with the 

increase in soy flour witch is in agreement 

with the study of Banureka and Mahendran 

[17]. This may be explained by the fact 

that soy flour contains a higher amount of 

solid dry substance with emulsifying 

properties compared to wheat flour. During 

biscuits storage the moisture content 

increased, but R3 and R4 showed greater 

storage stability (Fig. 2). The saturation 

capacity decreased during four weeks of 

storage, between the moisture content and 

saturation capacity there was an inverse 

correlation (Fig. 3). 
 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 

Volume XVI, Issue 4  – 2017 

 
Flavia POP, Zorica VOȘGAN, Lucia MIHALESCU, Supplementation of wheat flour with soy flour, sensory and 
physicochemical evaluation of fortified biscuits Food and Environment Safety, Volume XVI, Issue 4 – 2017, pag. 250 – 255   

253 
 

 

Table 2.  

Proximate analysis of biscuits 

Parameters R1 R2 R3 R4 

Fat (%) 16.34 ± 0.03 17.31a ± 0.02 19.07b ± 0.05 19.84bc ± 0.06 

Moisture (%) 3.62 ± 0.08 2.95a ± 0.04 2.63ab ± 0.02 2.07b ± 0.03 

Ash (%) 0.75 ± 0.01 1.45ab ± 0.05 1.59b ± 0.06 1.86bc ± 0.01 

Alkalinity (degrees of alkalinity) 2.73 ± 0.02 2.38a ± 0.01 1.82ab ± 0.01 1.25b ± 0.04 

Saturation capacity (g) 14.31 ± 0.05 18.82ab ± 0.03 21.76b ± 0.04 23.54bc ± 0.02 

Dough elasticity (%) 40.63 ± 0.04 29.35bc ± 0.04 26.12c ± 0.03 23.78cd ± 0.05 
Values are means of triplicates ± standard deviation. Values with the same superscript in a column are not significantly 
different (P > 0.05).  

 

 
 

Fig. 1. Acidity variation during storage of biscuits 

 

 
Fig. 2. Moisture variation during storage of biscuits 

 

 
Fig. 3. Saturation capacity variation during storage of biscuits 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 

Volume XVI, Issue 4  – 2017 

 
Flavia POP, Zorica VOȘGAN, Lucia MIHALESCU, Supplementation of wheat flour with soy flour, sensory and 
physicochemical evaluation of fortified biscuits Food and Environment Safety, Volume XVI, Issue 4 – 2017, pag. 250 – 255   

254 
 

 

 

Farzana and Mohajan studied the 
incorporation of soy flour to wheat flour 
and the quality of biscuits fortified with 
mushroom. The researchers reported that 
protein content of soy flour-supplemented 
biscuits increased from 11.07% to 17.86% 
as compared to control and a significant 
increased in fat (17.36-20.89%), fiber 
(0.48-0.92%), iron (1.56-1.99 mg/100 g), 
and energy value. The results from 
chemical analyses indicated that good 
quality biscuits can be prepared by 
replacing wheat flour with 15% soy flour 
and addition of mushroom powders may 
affect the backing quality [14]. Mildner-
Szkudlarz et al., studied the incorporation 
of white grape pomace in wheat flour at 
levels of 10, 20 and 30% and its influence 
on rheological, nutraceutical, physical and 
sensory properties of dought and biscuits. 
The researchers concluded that dough with 
different levels of white grape pomace 
showed a decrease in water absorption and 
the addition of white grape pomace 
reduced hardness and caused deterioration 
in brightness and yellowness of all the 
enriched samples. The results showed that 
the smallest addition of white grape 
pomace caused an approximately 88% 
increase in total dietary fibre content as 
compared to control. The content of 
phenolic compounds increased with the 
addition of white grape pomace and 
enhanced the antioxidant properties of 
biscuits, while acceptable biscuits were 
obtained when incorporating 10% white 
grape pomace [18]. To assess the state of 
freshness we used the descriptive sensory 
analysis, which is an ideal technique to 
identify flavors in a product and to 
distinguish the products between them, 
using tasters familiar with methods of 
scoring and sensory language. 
The organoleptic test of the products was 

done by the 5-point hedonic scale and was 

performed on a sample of 10 trained 

panelist, aged between 20 and 55 years, 

according to the method described by 

Farzana and Mohajan, [14]. Selected 

attributes were: smell, taste, color, 

appearance and texture (Fig. 4-6). 

 

0

1

2

3

4

5
smell

taste

colorappearance

consistency

 
Fig. 4. Sensory analysis of biscuits with 10% soy 

flour incorporation 

 

 
Fig. 5. Sensory analysis of biscuits with 20% soy 

flour incorporation 

 

0

1

2

3

4

5
smell

taste

colorappearance

consistency

 
Fig. 6. Sensory analysis of biscuits with 30% soy 

flour incorporation 

 

For sensory analysis the descriptive scale 

was the following: 1 = very little normal, 2 

= less than normal, 3 = moderately 

normal, 4 = almost normal, 5 = normal. 

The taste is the primary factor which 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 

Volume XVI, Issue 4  – 2017 

 
Flavia POP, Zorica VOȘGAN, Lucia MIHALESCU, Supplementation of wheat flour with soy flour, sensory and 
physicochemical evaluation of fortified biscuits Food and Environment Safety, Volume XVI, Issue 4 – 2017, pag. 250 – 255   

255 
 

 

determines the acceptability of any 

product, which has the highest impact as 

far as market success of product, is 

concerned. In the present study, sensory 

scores of biscuit enriched with 10% (R2) 

and 20% (R3) soy flour, showed that with 

regard to taste, color, smell, appearance, 

and consistency, the sensory characteristics 

of R2 were found to be the best.  

 

4. Conclusions 
 

During four weeks of storage at ambient 

temperature, acidity and moisture content 

showed an upward trend and were within 

the maximum admissible limits. Biscuits 

fortified with soy flour had a higher fat and 

mineral content as compared to wheat flour 

biscuits. From the sensory evaluation, the 

biscuits with 10 and 20% soy flour 

addition presented similar characteristics. 

The biscuits supplemented with up to 20% 

soy flour have shown superior nutritional 

characteristics as compared to wheat flour 

biscuits. Soy flour can be used efficiently 

in biscuit production technology. 
 

5. References 
 

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benefits of Soybean. Soy Protein Quality 

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Nutrition Paper No. 71, Rome, Italy, (2008). 

[2]. SLAVIN J.L., Dietary fiber and body weight, 

Nutrition, 21: 411-418, (2005). 

[3]. SUTHARSHAN S., SRIWARDANA T.D., 

MAHENDRAN T., Development of maize-soy 
based supplementary food and evaluation of quality 

parameters, Proceedings of the 57th Annual 

Sessions, Sri Lanka Association for the 

Advancement of Science, 26th November - 1st 

December, (2001). 

[4]. POP F., Milling Technology, Mega Publishing 

House, Cluj-Napoca, pp. 70-90, (2017). 

[5]. MIHALY COZMUTA A., POP F., Bakery 

Technology, Risoprint Publishing House, Cluj-

Napoca, pp. 120-140, (2008). 

[6]. WONG S.Y., Colorimetric determination of 

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[12]. CHEVALLIER S., DELLA VALLE G., 

COLONNA P., BROYART B., TRYSTRAM G., 

Structural and chemical modifications of short 

dough during baking, Journal of Cereal Science, 

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[13]. MIHALY COZMUTA A., POP F., CODRE 

A., Practical guidance on milling, bakery and pasta 

products technology, Risoprint Publishing House, 

Cluj-Napoca, pp. 21-37, (2007). 

[14]. FARZANA T., MOHAJAN S., Effect of 

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with mushroom, Food Science & Nutrition, 3(5):  

363-369, (2015). 

[15]. AYO J.A., AYO V.A., POPOOLA C., 

OMOSEBI M., JOSEPH L., Production and 

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[16]. SIDDIQUI N.R., HASSAN M., RAZA S., 

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[17]. BANUREKA V.D., MAHENDRAN T., 

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	*Corresponding author: flavia_maries@yahoo.com
	1. Introduction