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Rheological characterisation of gluten from extensibility measurement

D.N. Abang Zaidel a , N.L. Chin b, * , R. Abdul Rahman c, R. Karim c

a Department of Bioprocess Engineering, Faculty of Chemical Engineering and Natural Resources Engineering, Universiti Teknologi Malaysia,81310 Skudai, Johor, Malaysia

b Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysiac Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

Received 25 June 2007; received in revised form 5 October 2007; accepted 8 November 2007

Abstract

A simple tensile test set-up was built and attached to an Instron 5566 to determine gluten extensibility, comparing the performance of strong and weak our mixed for various mixing time. In this work, the gluten strip was clamped at two ends and extended upward at thecentre by a hook at speed of 300 mm min

À 1 . Parameters such as gluten length at fracture, measured force, actual force acting on thegluten strips, strain, strain rate and stress were obtained. Gluten obtained from strong our has greater extensibility compared to weakour. The extensibility of gluten from both strong and weak our dough increased as dough mixing time increased before decreasing at apeak of 8 min. The results demonstrated the capability of the tensile test set-up to describe the development of gluten during mixing of dough. Rheological characteristic of gluten indicated that gluten exhibited strain hardening effect during extension.Ó 2007 Elsevier Ltd. All rights reserved.

Keywords: Curve-tting; Extensibility; Gluten; Strain hardening; Tensile test

1. Introduction

Gluten is a cross-link of protein network developed dur-ing mixing of our–water dough. By washing the doughunder running water, the starch is removed and the remain-ing viscoelastic mass obtained is gluten. Nowadays, theuses of gluten in industry have been intensely applied invarious food and non-food applications. Day et al. (2006)reported that due to the unique cohesive properties of glu-ten, it has become a commercial material in food industry

including bakery, breakfast cereals, noodles, sausages andalso meat substitute. Its application has been expandingto other sectors such as pet food, aquaculture feed, naturaladhesives and also as biodegradable lms.

Rheological properties of gluten are always being con-nected to the quality of its end product: textural attributes,shape and expansion ( Amemiya and Menjivar, 1992;

Anderssen et al., 2004; Tronsmo et al., 2003 ) and theyhad been studied in terms of small and large deformationmeasurements ( Amemiya and Menjivar, 1992; Janssenet al., 1996; Uthayakumaran et al., 2002; Tronsmo et al.,2003). However, gluten quality measurement using largedeformation is more suitable for testing gluten applicationas food product as it can be related to its eating quality. Amaterial is subjected to a large deformation when the stressexceeds the yield value. A commonly adapted method forlarge deformation testing of dough and gluten is extension.

Various instruments are available in performing the exten-sion of dough and gluten such as the extensograph, textureanalyser and Instron. In this test, the sample was clampedat two ends and pulled or extended by a hook at the centreof the sample at a constant strain rate. Large deformationis applied to the sample until it fractured and the material isunable to regain the original shape. In the past, manyworks were done on extensibility of gluten and dough usingattachments on the Universal Testing Machine such as thetexture analyser and Instron ( Kieffer et al., 1998; Tronsmoet al., 2003; Dunnewind et al., 2004; Sliwinski et al.,

0260-8774/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jfoodeng.2007.11.005

* Corresponding author. Tel.: +60 3 89466353; fax: +60 3 86567123.E-mail address: [email protected] (N.L. Chin).

www.elsevier.com/locate/jfoodeng

Available online at www.sciencedirect.com

Journal of Food Engineering xxx (2007) xxx–xxx

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Please cite this article in press as: Abang Zaidel, D.N. et al., Rheological characterisation of gluten from extensibility measurement,Journal of Food Engineering (2007), doi:10.1016/j.jfoodeng.2007.11.005

mailto:[email protected]

mailto:[email protected]



2004a,b ). Tronsmo et al. (2003) performed a uniaxialextension on dough and gluten using the Kieffer doughand gluten extensibility rig for the TA.TX2i texture ana-lyser to test the rheological properties. They used six differ-ent wheat ours to study the difference in the breadmaking

performance and determined the maximum resistance toextension and total extensibility. Another extensionalinstrument used to determine the extensibility of wheatour dough was Sentmanat Extensional Rheometer(SER) (Trevor et al., 2006 ). In this test, a rectangulardough sample was mounted onto two cylindrical drumsand was stretched until it fractured.

The main problem encountered in performing glutenand dough extensibility tests is to hold the sample so thatit breaks within the sample and not at the jaws that holdthe sample. This paper focuses on gluten extensibility mea-surement using a new tensile test set-up attached to Instron(5566 series, Instron Corporation, USA) and also its rheo-logical characterisation. Using this set-up, gluten extensi-bility was determined by studying the effect of variousmixing times on the development of gluten during doughmixing. Four rheological characteristics were determined:fracture strain, fracture stress, the coefficient, k and index,n. Fracture strain and fracture stress are the points whengluten fractured at its maximum extensibility. k and n,which indicate the extensional stiffness and strain harden-ing of gluten respectively, were determined from curve-t-ting of stress–strain curve following exponential equation,r = ke n e . Previous studies on biaxial extension of dough(Chin and Campbell, 2005; Dobraszczyk et al., 2003 ) tthe stress–strain curves following the exponential equationto obtain k and n.

Mixing time is one of the processing factors that inu-ence the gluten development during mixing other thanwork input, mixer type and temperature. The molecularmodel proposed by Belton (1999) and Le tang et al.(1999) suggested that at early stage of mixing, gluten brilsare formed as the water is in contact with our particles.Water is responsible in hydrating the protein brils andstarted the interactions between the proteins cross-linkswith the disulphide bonds. Too much water added to theour will result in slurry and too little water results in

slightly cohesive powder ( Faubion and Hoseney, 1989 ).

Thus, optimum water level must be used in developingcohesive, viscoelastic dough with optimum glutenstrength. As mixing proceeds, more protein becomehydrated and the glutenins tend to align because of theshear and stretching forces imposed. At this stage, gluten

networks are more developed by the cross-linking of pro-tein with disulphide bonds. At optimum dough develop-ment, the interactions between the polymers cross-linksbecome stronger and that leads to an increased doughstrength, maximum resistance to extension and restoringforce after deformation. When the dough is mixed pastits optimum development, the cross-links begin to breakdue to the breaking of disulphide bonds. The gluteninsbecome depolymerised and the dough is overmixed.The presence of smaller chains in the dough makes thedough stickier. Two types of our were used in thisstudy as different wheat our has different optimum mix-ing time (Hoseney, 1985 ). Longer mixing time is expectedfor mixing dough from strong our. It is probably dueto the dense particles of strong our through whichwater penetrates slowly ( Hoseney, 1985 ). Sliwinski et al.(2004a) reported that a positive correlation was observedbetween mixing time and the percentage of glutenin pro-tein on total protein in our. The effect of mixing timeon the rheological properties of gluten has been investi-gated by Amemiya and Menjivar (1992), Janssen et al.(1996) and Letang et al. (1999) .

2. Materials and methods

2.1. Dough preparation

Two types of our, Diamond N (12.33% protein) andSP-3 (8.81% protein), were used in this study and theyare referred as strong and weak our, respectively.Doughs were prepared by mixing 200 g our with water(63.4% for strong our; 59.5% for weak our) in mixer(5K5SS, KitchenAid, Belgium) for various mixing times:3, 5, 8, 11 and 15 min. Treated drinking water was usedto avoid any effect or reaction from other minerals onthe protein of our during our–water mixing. Doughwas left to stand in water for 1 h at room temperature

to rest (AACC, 1976 ).

Nomenclature

Ao original cross-sectional area of gluten (mm 2)At nal cross-sectional area of gluten (mm 2)d distance (gap) between the two clips (mm)

F a actual force (N)F m measured force (N)l o gluten original length (mm)l t gluten nal length at fracture (mm)V o original volume of gluten (mm 3)

V t nal volume of gluten (mm 3)yo gluten original position (mm)yt nal hook displacement at gluten fracture (mm)a

angle of deformation (°

)e H Hencky strain (dimensionless)_

e strain rate (sÀ 1)

r stress (N mmÀ 2)

2 D.N. Abang Zaidel et al. / Journal of Food Engineering xxx (2007) xxx–xxx

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2.2. Gluten washing and preparation

Rested dough was washed under running tap water atow rate of 2.5–2.8 ml s

À 1 to remove starch until glutenwas obtained. At the end of the washing, 1–2 drops of water from the gluten was squeezed into a container con-

taining clear water ( AACC, 1976 ). Starch is assumedabsent if cloudiness did not appear. As described in thework by Abang Zaidel et al. (2007) , the gluten, driedbetween dry cloths, was shaped into a ball shape andpressed to a thickness of 10 mm ( Fig. 1b) with the palm.Then, a paper clip with 10 mm gap was used to press ontothe gluten to print 10 mm width strips ( Fig. 1a) as guide forcutting using a paper cutter. Finally, the strips were cut to70 mm length. The 10 Â 10 Â 70 mm gluten strips of approximately 5.5 ± 0.5 g were immersed in tap water atroom temperature and left for 30 min to rest ( Chen et al.,1998; Chiang et al., 2006).

2.3. Tensile test

The rested gluten strip was then clamped at two endsusing plastic clips arranged at 40 mm distance nailed to a15.2 cm Â 21.6 cm wood platform cut according to the sizeof the Instron base platform. The wood was held tightly tothe Instron platform using a G-clamp. As described inAbang Zaidel et al. (2007) , the tensile test set-up consistsof a hook bent into a V-shaped using metal rod of 3.2 mm diameter and tted to the Instron (5566 series,Instron Corporation, USA) as shown in Fig. 2. The clipwas set 10 mm above the wood plane for easy opening of

the clamps when placing the gluten strips. To prevent thegluten strip from resting on the platform in between thetwo clips, the hook level was adjusted to match the level

of the clips as shown in Fig. 2b. The tensile test starts asthe gluten was pulled up by the hook at speed of 300 mm min

À 1 and stops when the gluten fractured. Threereplicates were performed and the error bars are the stan-dard deviation of the means. Fig. 3 shows the tensile testof a gluten strip extended by a hook at the centre. Mea-sured force ( F m ) is exerted on the gluten at a vertical axis.Extensibility parameters, such as the original length of glu-ten (l o ), the nal length of gluten at fracture ( l t) and actualforce (F a ), and rheological parameters, such as strain ( e H ),strain rate (

_

e ) and stress ( r ), were determined.

2.3.1. Derivation of extensibility parametersEq. (1) is used to determine the original length of gluten

(l o ) before being extended. d is 40 mm in this study. Thenal length of gluten at fracture ( l t) was calculated usingEq. (2):

l o ¼ 2 ffiffiffiffiffiffiffiffiffiffiðd =2Þ2 þ ð y oÞ2q ð1Þ

l t ¼ 2 ffiffiffiffiffiffiffiffiffiffiðd =2Þ2 þ ðy o þ y tÞ2q ð2Þ

Assuming that the hook is placed at the centre of the gap,the measured force ( F m ) was divided equally over bothstretched gluten at each side of the hook ( Dunnewindet al., 2004). The actual force ( F a ) that acted upon thestretched gluten was determined using the Eq. (4) whileEq. (3) shows the expression of the angle of deformation(a ) in terms of the measured and actual force which actedupon the gluten.

sin a ¼F m=2

F a¼

y t þ y ol t=2

ð3Þ

F a ¼F m l t

4ðy t þ y oÞð4Þ

Gluten

Paper clip

10mm

10mm

a

b

Gluten strips

13

10mm

70mm

2

Fig. 1. Gluten cutting using paper clip from (a) top and (b) cross-sectional

view.

Plastic clips

Wood platformRubberHook 40mm

a

bUpper partof clipLower

part of clip

Gluten strip

10 mm

Fig. 2. Tensile test set-up diagram from (a) top and (b) cross-sectionalview.

D.N. Abang Zaidel et al. / Journal of Food Engineering xxx (2007) xxx–xxx 3

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2.3.2. Derivation of rheological parametersThe extension parameters obtained earlier were used to

determine the rheological parameters such as strain, strainrate and stress. The Hencky strain ( e H ) acting on glutenwas calculated using the Eq. (5):

e H ¼ lnl t

l o ¼ lnffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

d =2ð Þ2 þ y o þ y tð Þ2

q ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffid =2ð Þ2 þ y oð Þ2q 0B@ 1CA ð5Þ

The strain rate was calculated by differentiating of Henckystrain (

_

e ) with time as shown in Eq. (6):

_

e ¼de H

dt ¼

dll tdt

¼1l t

Á2ðy t þ y oÞ

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi92 þ y t þ y oð Þ2q Ády tdt

¼4v y t þ y oð Þ

l 2t

ð6Þ

where v is the speed of hook (mm minÀ 1). The nal cross-

sectional area of gluten strip was calculated by assumingthe volume of gluten was constant throughout the test(Muller et al., 1961; Sliwinski et al., 2004a ) as providedin the Eq. (7).

V o ¼ V tAo l o ¼ At l t

At ¼Ao l o

l t

ð7Þ

where V o is the original volume of gluten (mm 3), V t is thenal volume of gluten (mm 3), Ao is the original cross-sec-tional area of gluten (mm 2) and At is the nal cross-sec-

tional area of gluten (mm2

). From the Eq. (8), the stress(r ) acted on the gluten was calculated by dividing the ac-tual force ( F a ) with the nal cross-sectional area of glutenstrip (At).

r ¼F aAt

ð8Þ

2.4. Data analysis

The experiments were conducted in triplicates. Meanand standard deviation were calculated using MicrosoftExcel. The error bars in the graphs are the standard devia-

tion of the means of three replications. Analysis of variance

(ANOVA), at alpha level = 0.05 ( P < 0.05), was performedusing a statistical software, Design Expert (Version 6.0.4,State-Ease Inc., Minneapolis, USA). The force-extensiongraphs were plotted from data obtained from Instronwhich were also used to calculate the extensibility parame-ters. Curves of strain-hook displacement, strain rate-hookdisplacement and stress–strain were obtained to study theperformance of the tensile test set-up.

3. Results and discussion

3.1. Dough and gluten preparation

Observations made during washing of gluten shows thatwashing time to obtain starch-free gluten for strong ourwas longer than weak our. This suggests that washingtime is inuenced by the our type and its protein content.With the same dough dimensions before washing, theweight of gluten obtained from strong our was slightly

higher compared to weak our. This explains that thequantity of wet gluten is higher from a higher protein con-tent our ( Curic et al., 2001).

3.2. Extensibility analysis

The gluten extensibility analyses are presented in twosections, i.e., the effect of mixing time on the gluten exten-sibility and rheological characterisation of gluten.

3.2.1. Effect of mixing time on gluten extensibilityFig. 4a and b shows the typical measured force-hook

displacement curves for gluten from strong and weak ourmixed for various mixing time. For both ours, an increaseof force was observed with increasing hook displacementand it decreased after reaching a peak. A similar trendwas reported in previous studies for gluten and dough inuniaxial extension tests ( Dunnewind et al., 2004; Sliwinskiet al., 2004a,b ), even though the dimensions of the glutenor dough sample used were different. At all mixing times,gluten extensibility showed similar patterns of increasingforce with increasing hook displacement reaching a maxi-mum before decreasing. From the curves, gluten fromstrong our gave higher force and hook extension thanweak our for all mixing times. This suggests that the

strong our has stronger protein network and gluten

Gluten strip at fracture

Original gluten stripF m

α

α

α

F a

F a

yo

yt

d

lt /2

lo/2

yo = gluten original position (mm)yt = final hook displacement (mm)

= angle of deformation (o

)d = distance (gap) between two clips (mm)F m = measured force (N)F a = actual force (N

Fig. 3. Schematic diagram of forces acting on gluten and the length of gluten during tensile test ( Dunnewind et al., 2004 ).


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strength as inuenced by the our protein content ( Curicet al., 2001).

Fig. 5 shows the effects of various mixing times on glu-ten extensibility. The length of gluten at fracture ( l t)increased as mixing time increased, reaching a peak beforeit decreased in further mixing indicating a typical doughdevelopment process. Gluten from both ours, mixed for8 min gave the highest value of l t. This suggests that doughmixed for 8 min reached the optimum development and atthis stage, the interactions between the polymers cross-linksbecame strong and leads to an increased dough strength,maximum resistance to extension and restoring force afterdeformation ( Letang et al., 1999). Gluten mixed for timesexceeding 8 min had lower extensibility values. Letanget al. (1999) explained that when the dough is mixed longerpast its optimum development, the cross-links begin tobreak due to the breaking of disulphide bonds and theglutenins becomes depolymerised and overmixed. Table 1shows the extensibility of gluten of strong and weak ourmixed for various mixing times at optimum water level.Analysis of variance shows that the effect of mixing timeon gluten extensibility was more signicant for the strongour gluten ( P < 0.003) than the weak our gluten

(P < 0.37).

Fig. 6 shows that the strain of gluten increased withincreasing hook displacement. The strain increase washigher at the beginning of gluten extension from thedecreasing slopes in the strain curves. For strong our,the gluten mixed for 8 min gave the highest value of strainbut it was not obvious for the weak our. The curves of strain rate versus hook displacement in Fig. 7 shows thatas the hook displacement increased, the strain rateincreased up to a peak before decreasing as the hook dis-placed further. Glutens from weak our gave higher strainrates compared to glutens from the strong our for all themixing times.

3.2.2. Rheological characterisation

Fig. 8 illustrates the stress–strain curves of glutensobtained from strong and weak doughs mixed for variousmixing times. The stress increased with increasing strainwith maximum values at sample fracture. The gradient of the curve is related to the modulus of gluten. The curvesdisplayed a curvature up to fracture indicating that themodulus increased with extension. This behaviour isknown as strain hardening, where the force to extend thematerial needs to increase for additional strain to occurand the stress increases more than proportional with thestrain ( Sliwinski et al., 2004c). This result was also reportedin previous studies on uniaxial extension test on dough andgluten (Sliwinski et al., 2004a,b,c ) and biaxial extension of dough ( Janssen et al., 1996; Chin and Campbell, 2005; Sli-winski et al., 2004b). Trevor et al. (2006) reported thatstrain hardening occurred at high strain rates where thestress increases more rapidly than linearly with the strain.

The failure stress and strain were obtained from thestress–strain values at gluten fracture. Fig. 9a and b showthat for both ours, the failure stress and strain increasedas the mixing time increased to 8 min before starteddecreasing. This agrees with Fig. 5 showing gluten mixedfor 8 min reaching its optimum development. At this stage,the interactions between the polymers cross-links becomestrong and it leads to increased dough strength, maximum

resistance to extension and restoring force after deforma-

0.0

0.4

0.8

1.2

1.6

0 50 100 150 200

y t (mm)

Fm

(N)

2 min5 min8 min11 min15 min

0.0

0.4

0.8

1.2

1.6

0 50 100 150 200

y t (mm)

Fm (N)


a b

Fig. 4. Measured force-hook displacement curves for gluten from doughs mixed using (a) strong and (b) weak our at various mixing times.

150

200

250

300

350

400

0 4 8 12 16Mixing time (min)

lt (mm).

Strong

Weak

Fig. 5. The gluten length at fracture from doughs mixed for variousmixing times.


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tion (Letang et al., 1999). Failure stress and strain forstrong our gluten were higher than weak our glutenfor all mixing times (Sliwinski et al., 2004b). Coefficient,k and index, n were determined by tting the stress–straincurves using an exponential equation, r = ke n e . The coeffi-cient of determination ( R 2) of the tted stress obtained forvarious mixing times was in the range of 0.91–0.99 as pre-sented in Fig. 8. Fig. 9c and d show that k increased and

then decreased with mixing time while n shows an opposite

trend from k . The strong our seems to have a slight fall inthe n value for 15 min mixing. k value for weak our washigher than strong our and the opposite was found forn value which is also reported for biaxial extension studyof dough ( Chin and Campbell, 2005 ). Higher k values inthe weak our gluten compared to the strong our glutensuggest that the earlier was extensionally stiffer. Higher nvalue was found in strong our explains that the strong

our gluten exhibit higher strain hardening properties than

Table 1Extensibility parameters of gluten at fracture from strong and weak our at various mixing times

Flour Mixing time (min) yt (mm) F m (N) l t (mm) F a (N) e H_

e (sÀ 1) r (N mm

À 2)

Strong 2 136.1 ± 5.6 1.40 ± 0.21 287.0 ± 11.0 0.71 ± 0.06 1.93 ± 0.04 2.08 ± 0.08 0.0489 ± 0.00585 136.1 ± 2.8 1.41 ± 0.16 287.0 ± 5.5 0.71 ± 0.05 1.93 ± 0.02 2.07 ± 0.04 0.0491 ± 0.00438 172.2 ± 5.6 1.43 ± 0.26 358.7 ± 11.0 0.72 ± 0.08 2.15 ± 0.03 1.86 ± 0.05 0.0618 ± 0.0059

11 140.3 ± 9.1 1.37 ± 0.14 295.3 ± 18.1 0.69 ± 0.04 1.95 ± 0.06 2.03 ± 0.12 0.0490 ± 0.005315 137.5 ± 7.2 1.49 ± 0.08 289.8 ± 14.3 0.77 ± 0.02 1.93 ± 0.05 2.09 ± 0.10 0.0523 ± 0.0038

Weak 2 90.3 ± 2.8 0.57 ± 0.04 196.7 ± 5.4 0.29 ± 0.02 1.55 ± 0.03 2.99 ± 0.08 0.0137 ± 0.00085 83.3 ± 4.8 0.58 ± 0.05 183.1 ± 9.4 0.30 ± 0.03 1.48 ± 0.05 3.21 ± 0.16 0.0131 ± 0.00128 97.2 ± 2.8 0.91 ± 0.07 210.3 ± 5.5 0.46 ± 0.04 1.62 ± 0.03 2.80 ± 0.07 0.0234 ± 0.0023

11 94.4 ± 7.3 0.78 ± 0.09 204.9 ± 14.4 0.40 ± 0.05 1.59 ± 0.07 2.90 ± 0.19 0.0193 ± 0.001515 94.4 ± 5.6 0.84 ± 0.05 204.9 ± 10.9 0.43 ± 0.02 1.59 ± 0.05 2.89 ± 0.16 0.0210 ± 0.0020

± Standard deviation of mean of three replicates.

0.0

0.5

1.0

1.5

2.0

2.5

0 50 100 150 200yt (mm)

0 50 100 150 200yt (mm)

Strain


0.0

0.5

1.0

1.5

2.0

2.5

Strain


a b

Fig. 6. Strain versus hook displacement for gluten from doughs mixed using (a) strong and (b) weak our at various mixing times.

0

2

4

6

8

0 50 100 150 200

yt (mm)

0 50 100 150 200

yt (mm)

Strain rate (s-1)

Strain rate (s-1)


0

2

4

6

8


a b

Fig. 7. Strain rate versus hook displacement for gluten from doughs mixed using (a) strong and (b) weak our at various mixing times.


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the weak our gluten, of which is in agreement with Sliwin-ski et al. (2004c). Strain hardening prevents premature frac-tures of dough and gluten and allow large extensions beforerupture ( Chin and Campbell, 2005; Sliwinski et al., 2004c ).

4. Conclusions

Determining the extensibility of gluten using the tensiletest set-upwassuccessfulin terms of providingtheextensibil-ity measurements where gluten do not fracture at the clamp-ing areas. The extensibility of gluten from both strong and

weak our dough increased as dough mixing time increased

to a peak of 8 min before decreasing. At this stage the glutendevelopment is at its optimum and further mixing of doughbeyond this optimum time results in reduction in glutenextensibility. The extensibility parameters of gluten fromstrong our gave higher values than weak our in term of the length at fracture, measured and actual force, strainand also stress. These results are supported by the higherstrain hardening properties of the strong our gluten, whichprevents early fracture of gluten samples. This work illus-trated that the behaviour of gluten development during mix-ing can be predicted by the rheological characterisation of

gluten. Thus, the results also demonstrated the capability

0.00

0.02

0.04

0.06

0.08

0.0 0.5 1.0 1.5 2.0 2.5Strain

0.0 0.5 1.0 1.5 2.0 2.5Strain

Stress (N mm

-2)

Stress (N mm

-2)


0.00

0.02

0.04

0.06

0.082 min5 min8 min11 min15 min

R2= 0.9987R2= 0.9993R2= 0.9355R2= 0.9796R2= 0.9988

R2= 0.9943R2= 0.9827R2= 0.9933R2= 0.9960R2= 0.9168

a b

Fig. 8. Stress–strain curves for gluten from doughs mixed using (a) strong and (b) weak our at various mixing times.

1.0

1.5

2.0

2.5





Failure strain

strong

weak

strong

weak

strong

weak

strong

weak

0.00

0.02

0.04

0.06

0.08

Failure stress (N mm-

2)

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

Coefficient, k

1.5

2.0

2.5

3.0

Index,n

a b

c d

Fig. 9. Graph of (a) failure strain, (b) failure stress, (c) k , and (d) n for gluten from doughs mixed using (a) strong and (b) weak our at various mixingtimes.


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of thetensile testset-up to describe thedevelopment ofglutenduring mixing of dough.

Acknowledgement

The authors wish to thank Malayan Flour Mill Sdn

Bhd, Malaysia for supplying the our for this study.References

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Please cite this article in press as: Abang Zaidel, D.N. et al., Rheological characterisation of gluten from extensibility measurement,Journal of Food Engineering (2007) doi:10 1016/j jfoodeng 2007 11 005

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