Freezing technology is commonly being employed for the storage of different
food products in the developed countries. The production of frozen dough
has increased tremendously because of its direct sales to the consumers
and rapid growth in number of in-store bakeries. The demand for quick
and convenient food has also increased manifolds because of the change
in daily life styles.
Rheologic behavior of food materials is important for new product development,
equipment design, process improvement and food quality control. Thus,
it is desirable that foods be characterized through experimental values
or parameters obtained in the determination of their rheologic properties.
Because of the simplicity of operation and the requirement of a rather
simple texture-measuring instrument, texture profile analysis (TPA) and
stress-relaxation tests are two textural methods used to determine the
behavior of food products (Yadav et al., 2006).
The frozen dough product segment has been considered to be the third
largest in the baking industry in the developed countries. The fast developing
frozen dough industry is becoming an easy and feasible alternative to
the traditional bakery products. The consumers demand breads from frozen
dough that possess a desirable quality and sensory characteristics comparable
to the traditional fresh breads.
Frozen dough has attained an important position in the world market and
has huge potential of growth due to its high market potential and current
lack of competition. The total market for frozen dough products covers
retail grocery sales and food service but due to increase in the demand
of frozen dough products, several major industrial groups have entered
into this business. The trend for more meals prepared outside of the home
has also reflected rapid growth in frozen dough (Schroeder, 1999).
The frozen dough production and utilization may confront certain problems
that can be overcome by the use of certain additives. These compounds
interact with water and can affect the quality of the end bakery product.
These compounds also possess water binding and gelling properties. The
proteins from dairy sources, like whey proteins, have been reported to
be safe and natural food additives that exhibit the capability of thickening
functions similar to the hydrocolloids, starches and other thickeners
in food systems (Hudson, 2000).
Incorporation of dairy ingredients into the frozen dough system improves
the baking quality and can be more beneficial than chemical additives.
It will also help to improve the nutritional value of the product. The
whey proteins after modification possess several functional properties
such as hydrophilic, water retention capacity and gelling capacity (Morr,
1992; Zayas, 1997). The whey protein is widely used as a dough-enhancing
additive, conferring a protective effect on the gluten network in the
frozen dough system (Jacobson, 1997).
Frozen doughs with the addition of heat treated whey protein concentrates
as functional ingredients have shown the improvement in gluten network
and baking performance (Kenny et al., 2001). This improvement has
attributed to its ability to counteract the rheological changes that occur
in frozen storage (Wolt and D’Appolonia, 1984).
The rheological properties of dough are primarily used as quality indicators
for the production of final products. These properties are measured in
the past few decades through a variety of instruments, empirical, fundamental
and dynamic rheometery (Steffe, 1996). Fundamental rheometery describes
the physical properties of a material over a wide range of strains and
strain rates. Direct comparison of results obtained by various testing
instruments and researchers can be carried out by the use of this technique
Knowledge of the rheological behavior of wheat flour dough is important
in the bread making process and to produce better quality cereal products
(Letang et al., 1999). Wheat flour dough is a viscoelastic material
and its characteristics mainly depend on the properties and composition
of the flour and the quantity of water added. Rheological testing has
been used to follow the changes in dough systems to determine fundamental
dynamic properties. (Huang and Kaletunc, 2003). The objective of this
research work was to determine the effect of modified whey protein concentrates
on the instrumental texture profile analysis of frozen dough.
Materials and Methods
Procurement of raw material: The commercial wheat flours of three
different protein contents, baker’s special superfine castor sugar,
baker’s salt and ascorbic acid were procured from The King Arthur
Flour Company, Inc., Norwich, Vermont. Saf-instant yeast manufactured
by SAFMEX for: LESAFFRE Yeast Corporation Milwaukee, Wisconsin and Crisco,
all-vegetable shortening manufactured by The J.M. Smucker Company, Orrville,
OH, were purchased from a local supermarket in USA.
Production of modified whey protein concentrates: Modified whey
protein concentrates (mWPC) used in this study as frozen dough functional
ingredients were produced by following the procedure of Resch and Daubert
Preparation of dough: Doughs were prepared from three different
wheat flours with and without the addition of mWPC as shown in the following
Texture profile analysis of frozen dough: The frozen doughs after
thawing were evaluated for their textural properties with the Brookfield
LFRA Texture Analyzer. The dough samples were cut with a cylindrical die
to get the uniform size of 20mm width and 25mm height. A round disk probe
of 30mm diameter was used to exert the force in the middle of the each
dough sample. The dough samples were tested in TPA mode consisting of
two cycles with a recovery time of 10 seconds. The probe speed was 10mm/sec
and the distance of the probe was 75% of the products height. The data
were processed with Brookfield Texture Prolite Version 1.0 software package
provided by Brookfield Engineering Laboratories, Inc. USA. The parameters
such as hardness, cohesiveness and adhesiveness of dough were determined
using the method of Bourne (1978); Manohar and Rao (1999).
Statistical analyses and software: Data for texture analysis of
the dough were processed with Brookfield Texture Prolite version 1.0 software
package provided by Brookfield Engineering Laboratories, Inc. USA and
it was subjected to statistical analyses to determine the level of significance
between texture parameters of different treatments by using completely
randomized design and means were compared according to the appropriate
methods described by Steel and Torrie (1997).
Results and Discussion
In this study, TPA parameters were used to verify the changes of the
textural attributes of frozen dough made from the wheat flours of different
protein contents and with different treatments of modified whey protein
concentrates according to the treatments as shown in Table
1. The textural parameters of food products have been established
using the TPA methodology, which gives excellent correlations with the
results of organoleptic analysis (Bourne, 2002). For this study, a sensory
analysis was not included.
There are two methods to evaluate food texture, namely sensory and instrumental
methods. The sensory method of developing a texture profile utilizes a
human taste panel and provides the ultimate test, which cannot be completely
duplicated by any instrumental procedure.
Texture profile analysis (TPA) method is widely used for texture evaluation
of food products. Human eating action normally consists of several bites.
In order to better describe the eating actions of humans, the TPA method
was presented by Peleg (1976). The TPA test performs two bites; every
bite includes compression and decompression cycles.
|| Texture Profile Analysis of frozen dough.
The results pertaining the analysis of variance and mean sum of squares
of instrumental texture parameters of frozen dough are shown in Table
Hardness: The analysis of variance for the hardness of frozen
dough prepared from different treatments is shown in Table
2. The analysis of variance showed that the effect of different treatment
and storage was highly significant whereas interaction between treatment
and storage was found to be non significant on the hardness of frozen
Statistical means for the hardness of frozen dough of different treatments
have been presented in Fig. 1. The mean score for the
hardness of frozen dough ranged from 412.33-503.23. It is evident from
the results that lowest values for the hardness of frozen dough were recorded
from the wheat flour with 9.2% protein contents (T1) and higher
values of frozen dough were recorded made from T3 and T5
with 12.7 and 14.2% protein contents wheat flours respectively for the
hardness measurement in TPA instrument. This trend showed that with the
increase in protein contents of wheat flours an increase in the values
of the hardness of frozen dough were observed. The results also indicated
that addition of mWPC in wheat flours resulted in the lowering values
of hardness of the frozen dough in all treatment, which means that addition
of mWPC induces a softening effect on the dough system.
The results for the values of hardness varied from 396.33-500.94 during
different storage periods. The results also represent a steady increase
in the values of hardness with the increasing frozen storage periods of
time up to 60 days.
The results found in this study are in close agreements to the findings
of Gambaro et al. (2002, 2004, 2006) as they previously conducted
texture profile studies on frozen dough and they found a significant increase
in the values of hardness of dough with the increasing storage periods.
Cohesiveness: The results pertaining to the analysis of variance
for cohesiveness of frozen dough with different mWPC treatments at different
storage intervals revealed that cohesiveness was affected significantly
by different treatments as well as storage periods. The interaction between
the treatments and storage periods did not affect significantly the cohesiveness
of frozen dough.
Values of means for the cohesiveness of frozen dough ranged from 0.41
for (T2) to 0.74 (T5) for the dough made from 14.2%
protein contents wheat flour among different treatment as shown in Fig.
1. The results also represent that with the increasing protein contents
in the wheat flours, the values of cohesiveness increased in the frozen
dough which could be seen as lower cohesiveness values in T1
and significantly higher ones in T3 and T5, respectively.
A decreasing trend in the values of cohesiveness was observed with the
addition of mWPC treatments in the frozen dough.
Results shown in Fig. 1 also represent that the statistical
mean values of cohesiveness from zero to 60 days varied from 0.50-0.69
across different storage intervals. The values were maximum at zero days
and then significantly decreased values of cohesiveness of the frozen
dough were observed with the increasing storage periods. The results found
in this study are in close agreement to the findings of Gambaro et
al. (2006). According to them, increase in the frozen storage periods
resulted in a decrease in the cohesiveness of dough samples.
Gumminess: The results pertaining to the analysis of variance
for the gumminess of frozen dough with different mWPC treatments and at
different storage intervals showed that gumminess of frozen dough was
affected significantly both by different treatments as well as by different
|| Experimental design of flour samples
|| Mean Sum of squares for the instrumental texture analysis
of frozen dough
|** = Highly Significant, (P < 0.01),
N.S = Non Significant
The interaction between the different treatments and different storage
periods was found to be non significant for the gumminess of the frozen
The mean values for the gumminess of frozen dough ranged from 240.83-364.25
among different treatments. However the gumminess mean values varied from
286.06-352.33 across different storage intervals as shown in
Fig. 1. A significant decrease in the mean values of gumminess were
observed with the addition of mWPC treatments in frozen dough as significantly
lower values of gumminess have been observed in T2, T4
and T6 when compared with the T1, T3
and T5, respectively.
The results also described that gumminess of frozen dough increased with
the increase of storage period and it was significantly lower at 0 day
and it increased significantly by increasing frozen storage periods.
Adhesiveness: The results regarding the analysis of variance for
the adhesiveness of frozen dough prepared with different treatments showed
no significant differences among different mWPC added treatments of frozen
dough while it was affected significantly by the different storage periods.
Results also indicate a non-significant interaction among treatments and
The statistical means for the adhesiveness of frozen dough measured with
TPA instrument ranged between -294 and -357 and results shown in Fig.1
represent a significant increase in the values of adhesiveness with the
increase of storage periods.
Springiness: The results for the springiness of frozen dough prepared
from different mWPC treatments and at different frozen storage intervals
have been given in Table 2 which illustrated the significant
effect of different treatments and storage periods. It was also found
that the interaction between treatments and storage periods was found
to be non significant for the springiness values of frozen dough measured
by TPA instrument.
Values of the statistical means for the springiness of frozen dough ranged
from 4.62-6.92 among different treatments as shown in Fig.
1. The results also represent that a decreasing trend in the values
of cohesiveness was observed with the addition of mWPC treatments in the
The statistical mean values of springiness from zero to 60 days varied
from 4.95-6.84 across different storage intervals. The results shown in
Fig. 1. also represent a significant decrease in the values of springiness
with the increasing storage periods. The values were significantly maximum
at zero day and then a significantly gradual decrease in the values of
springiness were observed with the increasing storage periods in the frozen
Conclusion: The instrumental texture analysis study of frozen
dough showed that addition of mWPC significantly decreased the values
of hardness, cohesiveness, gumminess and springiness. The storage increased
the hardness, gumminess and adhesiveness while a decrease in the values
of cohesiveness and springiness was recorded. The lack of significant
interaction shows that the mWPC addition did not eliminate the changes
in frozen bread dough caused by storage.
This paper is the part of PhD research which has been conducted at the
North Carolina State Universitry, USA. Authors are highly thankful to
Higher Education Commission, Pakistan, for the provision of generous funding
to complete this research work.