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Food Hydrocolloids 23 (2009) 1687–1692

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Food Hydrocolloids

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Effect of modified whey protein concentrates on empirical and fundamentaldynamic mechanical properties of frozen dough

Ali Asghar a,*, Faqir Muhammad Anjum a, Jonathan C. Allen b, Christopher R. Daubert b, Ghulam Rasool a

a National Institute of Food Science and Technology, University of Agriculture, Faisalabad 38040, Pakistanb Department of Food, Bioprocessing and Nutrition Science, North Carolina State University, Raleigh, NC 27695-7624, USA

a r t i c l e i n f o

Article history:Received 2 June 2008Accepted 6 January 2009

Keywords:Dough rheologyFrequency sweepMixographModified whey protein concentrates

* Corresponding author.E-mail address: ali_asghar11@hotmail.com (A. Asg

0268-005X/$ – see front matter � 2009 Elsevier Ltd.doi:10.1016/j.foodhyd.2009.01.005

a b s t r a c t

Dairy byproduct proteins are considered natural functional additives having the ability to interact withthe starch and gluten network in a dough system and thus behave as dough improvers. Native wheyproteins have negative effect in bread making so whey protein concentrates modified to increaseviscosity in solution (mWPC) might overcome undesirable weakening of the gluten network whichusually occurs in frozen dough products during prolonged times in frozen storage. The objective of thisresearch project was to determine the effect of mWPC on empirical and fundamental dynamic rheo-logical properties of wheat flour dough. The results for empirical rheological studies showed thataddition of mWPC had significant effects on mixographic parameters and also increased values of mixingtime and peak height percentage. The results for the fundamental mechanical properties of the frozendough revealed an increase in the values of G0 with the increase in the frequency, along with an upwardtrend with increasing temperature, but the highest values were obtained after cooling. Addition ofmWPC in the dough treatments induced softening in the dough system, as shown by the decrease in thevalues of the viscoelastic moduli. Rheological and textural changes in the bakery products made fromfrozen dough could be imparted by the incorporation of modified whey protein concentrates as doughimprovers.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Rheological properties of dough can be used as quality indica-tors for cereal products. A variety of instruments, empirical andfundamental, have been used for rheological testing of doughproducts (Steffe, 1996). Fundamental rheometry is capable ofdescribing the physical properties of a material over a wide range ofstrains and rates, allowing direct comparison of results obtained byvarious testing instruments and researchers (Weipert, 1990).

Rheological measurements and analysis of the stability of foodmaterials during and after processing can influence food processorson their selection of appropriate processing methods (Huang &Kaletunc, 2003). Knowledge of the rheological behavior of wheatflour dough is important in the bread making process to producebetter quality cereal products (Letang, Piau, & Verdier, 1999). Wheatflour dough is a viscoelastic material, and its characteristics mainlydepend on the properties and composition of the flour, the quantityof water added, and the mixing conditions. Rheological testing hasbeen used to follow the changes in dough systems to determine

har).

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fundamental mechanical properties. Shelf life of fresh bakeryproducts is usually a few days, and frozen dough bakery products aregood alternatives. Freezing and thawing in the frozen dough leads todecreasing dough strength, resulting in the reduction of final loafvolumes (Bloksma, 1990; Resanen, Laurikainen, & Autio, 1997).

The use of new additives is becoming a common practice in thebusiness of baking. Water distribution changes that occur duringextended frozen storage and freeze thaw cycles contribute to theextended proofing time and reduced loaf volume of frozen doughbreads (Berglund, Shelton, & Freeman, 1991; Varriano, Hsu, &Mahdi, 1980). Spoilage in the frozen dough bakery products usuallyhappens because excessive moisture becomes available in thefrozen dough systems during prolonged storage and formation andgrowth of ice crystals disrupt the gluten network. Use of waterbinding compounds, such as hydrocolloids and humectants, helpsabsorb excessive moisture that is released following the breakdownof the gluten network (Asghar, Anjum, Tariq, & Hussain, 2005;Asghar, Anjum, Butt, Tariq, & Hussain, 2007).

Whey proteins from dairy sources are considered natural foodadditives with thickening functionality similar to hydrocolloids,starches, and other thickeners in food systems (Hudson, Daubert, &Foegeding, 2000). Incorporation of dairy ingredients into the frozen

A. Asghar et al. / Food Hydrocolloids 23 (2009) 1687–16921688

dough system improves the baking quality, and can be morebeneficial than synthetic additives because of the high nutritionalvalue and natural origin of dairy products. Whey protein aftermodification can increase viscosity in solution and is widely used asa dough-enhancing additive, conferring a protective effect on thegluten network in the frozen dough system (Jacobson, 1997).

Frozen doughs with the addition of modified whey proteinconcentrates as functional ingredients showed an enhanced glutennetwork and also resulted in improved baking performance (Kenny,Wehrle, Auty, & Arendt, 2001). This may be due to its ability tocounteract the rheological changes that occur in frozen storage(Wolt & D’Appolonia, 1984).

Small deformation oscillatory rheological testing is a powerfultool for examining the fundamental viscoelastic properties ofdough. This technique offers the opportunity to study structuralproperties under a relatively extended range of conditions. Itsimultaneously measures the viscous and elastic characters of thedough (Khatkar & Schofield, 2002) and gives a better prediction ofthe final quality of cereal products (Shiau & Yeh, 2001). Theobjective of this research project was to determine the effect ofmWPC addition on the mixographic parameters of undevelopeddough and also to determine the effect on viscoelastic properties offrozen wheat flour doughs at different temperatures.

2. Experimental

2.1. Procurement and chemical composition of raw material

Commercial wheat flours of three different protein contents,Baker’s special superfine castor sugar, baker’s salt, and ascorbic acidwere procured from The King Arthur flour company, Inc. Norwich,Vermont, and were used in this study for making of doughs.Commercial wheat flours were analyzed for moisture, crudeprotein, total ash as well as wet and dry gluten content according toAACC methods (AACC, 2000).

2.2. Modified whey protein concentrate (mWPC) powderproduction

Modified whey protein concentrates (mWPC) used in this studyas frozen dough functional ingredients were produced according tothe method of Resch and Daubert (2002). According to this method,first whey protein concentrates powder was dispersed in thedeionized (DI) water to form protein solution and allowed to stir forabout 1 h. The solution was transferred, for thermal treatment, toa double-jacketed steam kettle equipped with a scraped surfaceagitator. The solution temperature was increased to 80 �C atapproximately 5 �C/min and held at 80 �C with constant agitationfor 1 h. After thermal gelation, gels were placed at 5 �C for at least24 h. Frozen gels were dried in a MR-TR Mechanically RefrigeratedFreeze-Mobile freeze dryer with tray drying chamber (VirtisResearch Equipment, Gardiner, NY). The dryer operated ata condenser temperature of�55 �C and a pressure of 15 m while theshelf temperature was slowly increased from�30 �C to�20 �C overa drying period of about 96 h. Gels were dried until moisturecontent was below 5% and removed from the freeze drier pans.Dried gels were crushed by hand, then ground with a ZM-1Brinkman Centrifugal Grinding Mill equipped with a 24-toothstainless-steel rotor (Brinkman Instruments, Inc., Westbury, NY) at10,000 rpm for 60 s and then this modified whey protein concen-trate powder was stored in the airtight bags for further use.

2.3. Empirical rheological measurements

Empirical rheological measurements of undeveloped doughsfrom three commercial wheat flours of different protein contents

with and without the addition of mWPC were tested on a Mixo-graph (National Mfg. Co., USA.) to determine the mixing behavior ofwheat flours according to the method number 54-40A of AACC(2000).

2.4. Dough preparation

Frozen dough was prepared by the straight no time doughformulation procedure of Inoue and Bushuk (1996) with someminor modifications (Asghar et al., 2005), using 2% yeast, 4% sugar,5% shortening 1% salt, 100 ppm of ascorbic acid and optimumamounts of water based on water absorption capacity measured bythe farinographic instrument. Commercial wheat flour containing9.2% protein was named as PF (pastry flour) while flours containing12.7 and 14.2% protein were named as BF (baker’s flour) and HF(high-protein flour), respectively. In the experimental design, floursmade with 9.2 and 14.2% protein were used directly or fortifiedwith 5% mWPC while 12.7% protein content flour was used directlyor fortified with 2.5% mWPC. After mixing, doughs were wrappedimmediately in polyethylene zip bags and stored in a freezer at�18 �C for one week after which they were slowly thawed andfundamental dynamic rheological studies of these doughs werecarried out.

2.5. Fundamental dynamic mechanical rheology

Dynamic oscillatory rheological measurements were performedon a controlled stress viscoelastic rheometer (StressTech, Rheo-logica Instruments AB, Lund, Sweden, ATS Rheosystems, Borden-town, NJ). The plate and plate system was used for measurements,with 20 mm diameter at a gap of 2 mm between plates. Smallpieces of wheat flour doughs were glued with instant adhesive(Loctite 401 manufactured by Loctite Corporation, USA) on bothupper and lower plates to minimize slippage. Samples were loadedbetween the plates and extra portions of the dough were trimmed.To prevent moisture loss and drying during the measurements, theedge of the sample was coated with synthetic multi-purpose grease(SuperLube, Bohemia, NY, USA). Before the experiments, doughsamples were allowed 5 min for equilibration.

Small deformation oscillatory measurements were performed ata frequency of 1 Hz and a strain of 1�10�3 to study the effect of themodified whey protein concentrates during the heating and cool-ing. Viscoelastic properties of these doughs were studied at 25 �C,90 �C and again after cooling at 25 �C and frequencies between 0.01and 10 Hz on the rheometer. Storage and loss moduli wereobserved as the function of frequency within the linear viscoelasticregion. Dough portions were removed from the rheometer aftermeasurement, and the plate surfaces were thoroughly cleaned withacetone to remove excess residue. Values were recorded by thesoftware Rheologica Rheoexplorer version 5 provided by Rheo-logica Instruments AB, Lund, Sweden, ATS Rheosystems, Borden-town, NJ. Results are means of three replications using differentdough preparations.

2.6. Statistical analysis

The data obtained from the empirical rheological values fromdifferent treatments of wheat flours with and without the additionof modified whey protein concentrates were subjected to statisticalanalysis to determine the analysis of variance and level of signifi-cance for different treatments and the differences in their meanvalues were determined by Duncan’s multiple range test accordingto methods described by Steel, Torrie, and Dickey (1997).

Table 2Mean squares for mixographic characteristics.

SOV Df Mixing time Peak height

Treatments 5 1.165** 18.488**Error 10 0.056 3.122

**, Highly significant (P� 0.01).

A. Asghar et al. / Food Hydrocolloids 23 (2009) 1687–1692 1689

3. Results and discussion

3.1. Physcio-chemical properties of commercial wheat flours

The results for the chemical composition of three raw wheatflours are shown in Table 1. Wheat proteins in the flour play a majorrole in the quality and loaf volumes of frozen dough bread. Gluten,being the major protein in the wheat flours, is responsible forviscoelastic properties (Stauffer, 1993). A strong gluten network isthought to be important for frozen dough stability (Nakamura &Kurata, 1997) because the doughs made from strong flours areusually resistant to freeze damage (Bushuk & Rasper, 1994). Severeprocessing conditions, such as freezing, storing, and thawing couldsignificantly weaken dough structure, so flour for frozen doughsshould have a good strength and high protein content (Wolt &D’Appolonia, 1984).

3.2. Empirical rheological measurements

The mixograph is one of the classical instruments used tomeasure empirical rheological properties of wheat flour dough(Shogren, 1990). The statistical values of mixing time and peakheight percentage of three different wheat flours with and withoutthe addition of mWPC are shown in Tables 2 and 3.

The results revealed that the values of mixing time and peakheight percentage differed significantly among the different treat-ments and the addition of mWPC to each of the wheat floursresulted in an increase in the mixing time. The highest mixing timewas 5.4 min which was for T6 (14.7% Protein flourþ 5% mWPC)followed by T5 (14.7% Protein flour) with the value of 4.8 min, whileT1 (9.2% Protein flour) had the lowest value recorded which was3.7 min. Similarly, addition of mWPC increased the values of peakheight percentage in each flour T6 (HF Flourþ 5% mWPC) had thehighest peak height percentage (54%) followed by T4 (BFFlourþ 2.5% mWPC) at 53%, while the lowest value of peak heightpercentage was obtained from T1 (PF Flour) at 46%.

To produce an optimum loaf of bread, dough must be mixed tothe peak of the mixing curve (Pomeranz 1987, 1988). In thisconnection, Anjum (1991) conducted empirical rheologicalstudies of wheat flours, but the results pertaining to mixogramsobserved were quite variable. These differences may be ascribedto the fact that in the present study wheat flour fortified withdifferent levels of mWPC rather than plain flour was tested withthe mixograph.

Dough mixing and water absorption properties of wheat flourswith the addition of dairy powders were determined previously byFinney and Shogren (1972). Larsen, Jenness, and Geddes (1949),Larsen, Jenness, Geddes, and Coulter (1951), Harper and Zadow(1984) and Erdogdu-Arnoczky, Czuchajowska, and Pomeranz

Table 1Chemical composition of different types of wheat flours (14% moisture basis).

Parameters PF flour (soft white/red winter)

BF flour (100% hard redspring wheat)

HF flour (100 % hard redspring wheat)

Protein (%) 9.20� 0.30 12.70� 0.20 14.20� 0.20Ash (%) 0.44� 0.02 0.48� 0.02 0.52� 0.02Wet gluten

(%)19.93� 2.13 29.34� 1.21 32.97� 0.98

Dry gluten(%)

7.52� 0.84 11.87� 0.34 12.88� 0.25

Fallingnumber(S)

280� 30 250� 30 250� 30

PF, 9.2% protein content flour; BF, 12.7% protein contents flour ; HF, 14.2% proteincontents flour.

(1996) found that addition of whey proteins after modificationchanged the empirical rheological properties of wheat flour dough.Increasing dough-mixing time also resulted in the improvement inthe stability of dough.

3.3. Fundamental dynamic mechanical rheology

The results for the mechanical spectra of three wheat floursstudied at a temperature of 5 �C are shown in Fig. 1 and it is evidentfrom the results that values of moduli increased with increase infrequency for all the three wheat flour doughs. The G0 values(storage modulus) are more than the G00 (loss modulus) for all thedoughs, which indicates that the doughs were more elastic than theviscous (Kulamarva, 2005). The moduli was higher in case of doughmade from higher protein flour (HF) as compared to the doughmade from medium and low protein flours which showed thatdough made from higher protein flour has better viscoelasticproperties.

The dynamic mechanical testing of doughs is affected bydifferent factors. Smith, Smith, and Tschoegl (1970) have reportedthat increasing oscillation frequency has shown to increase thevalues of G0 and G00 of flour doughs. The results shown in the presentstudy are in close agreements to the findings of Navickis, Anderson,Bagley, and Jasberg (1982) who found that protein content ofdoughs has been observed to affect dynamic moduli, indicatinghigher values as protein content increases.

The results regarding storage modulus are shown as a functionof frequency for the doughs made from three flours with differentprotein levels at temperature 25 �C, 90 �C and again at 25 �C aftercooling (Fig. 2). The dynamic moduli of the dough samplesincreased with the frequency, which refers to a more viscousbehavior of the samples. The absolute values of elastic modulus (G0)for all the three doughs made from flour of different proteincontents showed an increasing trend with the temperaturechanges, the highest value for moduli was given by the doughtested after cooling at 25 �C.

At 25 �C higher values of the G0 for the doughs made from higherprotein content observed as compared to the doughs made frommedium and low protein content flours. Similar trend for thesethree doughs has been observed when tested at other tempera-tures. The results also indicated that variation of G0 among threedoughs was wider at 25 �C and it decreased substantially whentested after heating at 90 �C and cooling the dough at 25 �C. The

Table 3Mixographic characteristics of wheat flour samples with mWPC addition.

Treatments Mixing time (min) Peak height (%)

T1 3.7� 0.20d 46� 2.08b

T2 4.2� 0.23cd 49� 0.58ab

T3 4.6� 0.15bc 51� 2.65ab

T4 4.7� 0.30b 53� 1.53a

T5 4.8� 0.15b 52� 2.00ab

T6 5.4� 0.25a 54� 2.65a

Values with the same letter in a column are not significantly different at a P� 0.05level.T1, 9.2% protein contents flour; T2, T1 Flourþ 5% mWPC; T3, 12.7% protein contentsflour; T4, T3 Flourþ 2.5% mWPC; T5, 14.2% protein contents flour; T6, T5 Flourþ 5%mWPC.

Log Freq (Hz)

0.001 0.01 0.1 1 10 100

Lo

g G

' G

" (P

a)

103

104

105

106

G'

G"

Dynamic moduli (closed symbols= G′, open symbols= G′′)

PF DoughBF DoughHF Dough

Fig. 1. Frequency sweep of three wheat flours doughs at 5 �C.

A. Asghar et al. / Food Hydrocolloids 23 (2009) 1687–16921690

higher dynamic moduli at higher frequencies imply more bondsinvolved in the mechanical response of the system due to a stress orstrain applied over a shorter time (Kulamarva, 2005). Dreese,Faubion, and Hoseney (1988) and Agyare, Xiong, Addo, and Akoh(2004) reported a similar trend for flour dough with G0 and G00

increasing with frequency.Greater amount of protein in water–starch–gluten system cau-

ses greater G0 and lower G00 (Rouille, Valle, Lefebvre, Sliwinski, & vanVliet, 2005). Dough having a good protein quality has a greater G0

than the weak doughs (Khatkar, Bell, & Schofield, 1995; Toufeiliet al., 1999). Hence, the doughs tested in this study presenteda predominantly elastic response, although a crossover point ten-ded to appear in the low-frequency regime.

3.4. Effect of modified whey protein concentrates on mechanicalspectra

Dairy proteins are important functional ingredients with uniqueproperties. It has also been found that dairy ingredients that increasewater absorption can improve dough-handling properties (Cocup &Sanderson, 1987; Kinsella, 1984; Stahel, 1983). The results for theaddition of mWPC and its effects on the fundamental dynamicmechanical rheology properties of frozen dough are shown in Fig. 3.

Log Frequency (Hz)

0.001 0.01 0.1 1 10 100

Lo

g G

' (P

a)

103

104

105

106

107

108

PF DoughBF DoughHF Dough

25 °C

90 °C

25 °Cafter heat

Fig. 2. Frequency sweep of three wheat flours at 25, 90 and after cooling at 25 �C.

The values of both storage and loss modulus were recordedduring the experiment. To simplify data, only the values of G0 areshown. Addition of mWPC resulted in the reduction of values ofmoduli for all the dough treatments, meaning that mWPC additionresulted in softening behavior in the dough system during thefrequency sweep measurements. Fig. 3 represents the results ofmechanical spectra on frequency sweep of frozen doughs with theaddition of mWPC. The doughs made from flour with 9.2% proteinwere fortified with 5% mWPC while addition of 2.5 and 5% mWPCwas made to wheat flours with 12.7 and 14.2% protein contents,respectively.

Increases in the values of G0 with the increase in the frequencieswas observed at all the three temperatures tested for all threedifferent wheat flour frozen doughs. According to results shown inFig. 1, higher values of G0 were observed at 90 �C and after cooling to25 �C, compared to the initial reading at 25 �C. Also, addition ofmWPC lowered G0 values at 5% addition in the frozen doughs madefrom PF and HF flours while in BF, a smaller difference betweenbasic wheat flour dough data and data from dough made from flourwith 2.5% additional mWPC was observed. It was also obvious fromFig. 3 that mechanical spectra of frozen dough showed a smallerfrequency dependence of G0 when the values were recorded at25 �C after heating and cooling.

Mechanical tests conducted within the linear viscoelastic regionare useful for understanding the dough properties in term ofphysical and chemical structure. The rheological properties of thedough reflect its machine properties during processing and thequality of an end product (Mani, Eliasson, Lindahl, & Tragardh,1992). Khatkar et al. (1995) and Kokini, Cocero, Madeka, and Graaf(1994) studied the role of proteins on the gluten behavior at smalldeformation dynamic oscillatory measurement of dough, whilechanges in the dough network were observed during the heatingprocess by Dhanasekharan, Wang, and Kokini (2001) and Hayta andSchofield (2005).

A similar trend in the dynamic rheological properties of doughswas found by Dreese et al. (1988) and Agyare et al. (2004).According to these authors, the values of G0 and G00 for flour doughincreased with the increases in frequency. Smith et al. (1970) foundthat increasing oscillation frequency increased the values of G0 andG00 of flour doughs.

The ability of modified whey protein concentrates to absorb andbind water is useful in connection with frozen doughs that aremixed, formed, and then held in frozen storage for some length oftime. The addition of mWPC resulted in apparent water absorptionin the dough system. Masi, Cavella, and Sepe (1998) and Kenny et al.(2001), found that with the increase in water content in the doughsystem, elastic modulus and viscous modulus decreased, resultingin softening in the dough. Jacobson (1997) concluded that wheyproteins may confer a protective effect on the gluten network in thefrozen dough system.

Values of the mechanical spectra of the doughs were evaluatedby linear curve fitting of logarithmic plots of G0 versus frequency asshown in Fig. 4. Statistical results represent that significant effectof the treatments and different temperature ranges. Also a signif-icant effect of the interaction between the treatments andtemperatures was observed. According to Hayta and Schofield(2004), the intercept values correspond to the magnitude of theelastic modulus and gives information about the frequencydependence of the sample. At 25 �C, a slight decrease in theintercept was observed with the addition of mWPC in the doughs.It was previously observed that high elastic modulus values withlow frequency dependence are related to good quality gluten(Janssen, Van Vliet, & Vereijken, 1996; Khatkar et al., 1995). Thus,according to this observation, mWPC exerted a softening effect onthe doughs.

PF Flour and 5% mWPC

Freq (Hz)

0.001 0.01 0.1 1 10 100

Lo

g G

' (P

a)

104

105

106

107

108

25 °C

25 °Cafter cooling

90 °C

BF Flour and 2.5% mWPC

Freq (Hz)

0.001 0.01 0.1 1 10 100

Lo

g G

' (P

a)

103

104

105

106

107

25 °C

90 °C

25 °Cafter Cooling

PF flour dough at 25 °C PFW flour dough at 25 °C PF flour dough at 90 °C PFW flour dough at 90 °C PF flour dough at 25 °C after coolingPFW flour dough at 25 °C after cooling

BF Flour dough at 25 °C BFW flour dough at 25 °C BF flour dough at 90 °C BFW flour dough at 90 °C BF flour dough at 25 °C after coolingBFW flour dough at 25 °C after cooling

Freq (Hz)

HF Flour Dough + 5% mWPC

10-3 10-2 10-1 100 101 102

Lo

g G

' (P

a)

103

104

105

106

107

25 °C

90 °C

25 °C after cooling

HF flour dough at 25 °C HFW flour dough at 25 °CHF flour dough at 90 °C HFW flour dough at 90 °C HF flour dough at 25 °C after coolingHFW flour dough at 25 °C after cooling

Fig. 3. Effect of mWPC addition on mechanical spectra of three wheat flour doughs.

4

4.5

5

5.5

6

6.5

7

7.5

PF PFW BF BFW HF HFW

In

tercep

t V

alu

es

Intercept (25 °C) Intercept (90 °C) Intercept (25 °C after heat)

LSD > 0.3

Fig. 4. Intercept values obtained from the regression lines of elastic modulus versusfrequency of frozen doughs with different treatments of mWPC.

A. Asghar et al. / Food Hydrocolloids 23 (2009) 1687–1692 1691

When the gluten dough was subjected to thermal treatment, anincrease in the intercept values of regression lines of mechanicalspectra was observed after heating to 90 �C and also after cooling,indicating a more elastic behavior with higher resistance todeformation. According to Sliwinski, Van der Hoef, Kolster, and VanVliet (2004) and Hayta and Schofield (2005), heating of gluten anddough up to 50 �C is accompanied by a reduction of G0, but a furtherincrease of temperature induces an increase in the elasticityreflected by lower frequency dependence and higher elasticmodulus due to the protein crosslinking and aggregation (Hayta &Schofield, 2004, 2005).

4. Conclusion

Dairy byproduct proteins after modification have functionalproperties much like hydrocolloids, so could be used as thickeners

A. Asghar et al. / Food Hydrocolloids 23 (2009) 1687–16921692

to bind extra moisture to improve textural stability and sensoryattributes in different frozen dough bakery items. Addition ofmWPC resulted in an increase in the values of mixing time and peakheight percentage of the wheat flours. Dynamic mechanical prop-erties of wheat flour doughs were also affected such that addition ofmWPC lowered moduli values during the rheological measure-ments at all the temperatures. Rheological and textural changes inbakery products made from frozen dough could be imparted by theincorporation of modified whey protein concentrates as doughimprovers.

Acknowledgements

Financial support from Higher Education Commission, Pakistanand North Carolina State University, USA, to conduct PhD researchwork is gratefully acknowledged. The skillful practical assistance ofSharon Ramsey (The Lab Manager of Food Rheology Lab in theDepartment of Food, Bioprocessing and Nutrition Sciences, NCSU)to conduct the fundamental dynamic rheology tests is also highlyappreciated. Authors are also indebted to NCSU for financialsupport to present part of this research work as an oral presenta-tion in the Chester Food Science and Technology Conference,Chester, UK, 2007.

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