Journal of Industrial and Engineering Chemistry 20 (2014) 1812–1818

Development of gluten-free flat bread using hydrocolloids:Xanthan and CMC

Mehrdad Mohammadi a, Nasim Sadeghnia a, Mohammad-Hossain Azizi b,Tirang-Reza Neyestani c,*, Amir Mohammad Mortazavian a

a Department of Food Technology Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology,

Shahid Beheshti University of Medical Sciences, Tehran, Iranb Department of Food Science and Technology, Faculty of Agriculture, Tarbiat Modarres University, Tehran, Iranc Department of Nutrition Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid

Beheshti University of Medical Sciences, Tehran, Iran

A R T I C L E I N F O

Article history:

Received 29 April 2013

Accepted 28 August 2013

Available online 6 September 2013

Keywords:

Gluten-free

Flat bread

Xanthan

CMC

Gluten replacer

A B S T R A C T

The effects of xanthan gum (XG) and (carboxymethyl cellulose (CMC) (5–20 g kg�1) on the quality

parameters of gluten-free flat bread, based on rice flour were investigated. Increase in CMC

concentration yielded bigger gas cells, leading to better crumb porosity. Formula 3 (F3), containing

15 g kg�1 XG and formula 10 (F10), containing 10 g kg�1 CMC and 10 g kg�1 XG resulted in the highest

dough yield (P < 0.05) and bread yield, respectively, and F10 showed the lowest bread weight loss

(P < 0.05). F10, followed by, F3 were the best and most acceptable (P < 0.05) formulae, compared to all

the others.

� 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights

reserved.

Contents lists available at ScienceDirect

Journal of Industrial and Engineering Chemistry

jou r n al h o mep ag e: w ww .e lsev ier . co m / loc ate / j iec

1. Introduction

Flat breads are the oldest and most well-known bread typesworldwide, with estimates showing that over 1.8 billion people usethis type of bread in regions of Central America, South Europe,Scandinavia, South Africa, the Middle East and part of China [1].Gluten protein functionality is important for bread quality anddifferences in the characteristics of the many varieties of breaddepend on their gluten protein content [2,3].

On the other hand, this protein can cause serious healthproblems in predisposed people [4]. Coeliac disease an autoim-mune immune enteropathy, caused by the ingestion of gluten ingenetically susceptible people [2], is a chronic intestinal inflam-mation caused by the consumption of glutamine and prolineprotein, which results in flattened mucosa villi [5]. The onlytreatment for this disease is to follow a lifelong gluten-free diet,facilitating mucosal recovery [4].

* Corresponding author at: Department of Nutrition Research, National Nutrition

and Food Technology Research Institute, Faculty of Nutrition Sciences and Food

Technology, Shahid Beheshti University of Medical Sciences, 1981619573, P.O. Box:

19395-4741, Tehran, Iran.

E-mail address: neytr@yahoo.com (T.-R. Neyestani).

1226-086X/$ – see front matter � 2013 The Korean Society of Industrial and Engineer

http://dx.doi.org/10.1016/j.jiec.2013.08.035

Producing bread from gluten-free flour is considered techno-logically critical. The absence of gluten has an impact on cellformation, crumb and crust characteristics, volume, porosity,quality parameters [6], mouth feeling and flavor [7]. Gluten-freebreads are mostly known for their lower quality compared towheat breads. Their dough has a batter form and the viscosity issimilar to that of cake batter. These breads need stabilizers, gumsand pre-gelatinization starches to trap and maintain gas [7].

Some types of flour and starch (rice, corn, cassava, soybean,millet, potato and peanut) and some materials such as hydro-colloids, enzymes (transglutaminase and lipoxygenas), soybeans,egg and dairy proteins have been used to imitate the viscoelasticproperties of gluten [8–12]. Rotsch indicated that bread doughswithout gluten can only keep gas if the gluten is replaced byanother gel [13]. Gums enhance the cohesion of the starch granulesand produce bread which can compete with wheat bread [14], butwithout the detrimental effects of gluten.

CMC is used for maintaining moisture, and improving themouth-feel and structural consistency of bakery products; it is alsoused in combination with other stabilizers and gums because of itshigh water-absorbing capacity [15].

The pseudoplastic property of xanthan gum is important duringdough preparation, i.e. pumping, kneading and rolling. Interactionsbetween xanthan and other polysaccharides can have synergistic

ing Chemistry. Published by Elsevier B.V. All rights reserved.

Table 1Quantities of ingredients (g) used in the formulation of breads batters.

Ingredients g

Corn starch 1750

Rice flour 750

De-fatted soy flour 500

Pre-gelatinized corn starch 100

Vegetable oil 100

Egg white 50

Salt 47

Sugar 47

Yeast 40

Sodium stearoyl lactylate 12.5

Xanthan Variable (see Table 2)

CMC Variable (see Table 2)

Gluten-free flat breads were prepared according to control manner and materials

but with the addition of hydrocolloids (xanthan and CMC).

Table 2Xantan and CMC contents (g kg�1) used in the formulation of gluten-free breads.

Formula Xanthan (g kg�1) CMC (g kg�1)

ControlA – –

F1B 5 –

F2B 10 –

F3B 15 –

F4C – 5

F5C – 10

F6C – 15

F7D 5 5

F8D 5 10

F9D 10 5

F10D 10 10

A Control (flat bread without hydrocolloids: xanthan and CMC).B Xanthan-containing formulae: F1, F2 and F3.C CMC-containing formulae: F4, F5 and F6.D Xanthan and CMC-containing formulae: F7, F8, F9 and F10.

The hydrocolloids were added as g kg�1 total flour basis (including: corn starch, rice

flour, soy flour and pre-gelatinized starch).

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–1818 1813

effects, such as enhanced viscosity or gelation effects e.g. withgalactomannans and glucomannans [16,17]. Xanthan increasesdough stability, water absorption and gas maintenance [18].Lazaridou et al. [19] indicated that, compared to CMC, pectin,agarose and b-glucan, xanthan had the lowest creep compliancevalues and the highest zero shear viscosity; it also had the mostenhanced elastic properties, probably due to its weak gelproperties and high viscosity values at low shear rates becauseof its stiffness and its arranged chain construction [19].

Mezaize et al. [20] optimized gluten-free formulae for French-style breads, based on rice and corn flour and potato starch usinghydrocolloids such as guar (1.9%), CMC (1%), hydroxypropylmethylcellulose (HPMC) (2.3%) and XG (0.6%) and obtained adecrease in hardness and an increase in specific volumes withHPMC and guar respectively. Cell size and porosity of gas increasedby adding guar gum and CMC [20].

Gluten-free bread with enhanced organoleptic properties canbe made by incorporating binding materials that mimic the effectsof wheat gluten operation in dough; these binding materials makea cell network, the stability of which facilitates the retention of gasproduced in baking, stimulates the attraction of starch granulesand, consequently, improves dough cohesiveness [21].

In literature a large number of flours and starches and varioushydrocolloids have been investigated to imitate the viscoelasticproperties of gluten in wheat doughs. The characteristics of gluten-free bread depend on the amount and type of hydrocolloids used asgluten replacers. The common point between the studies was thatamong hydrocolloids, xanthan and CMC showed the appropriatequality in bread manufacturing. Xanthan gum and CMC iscompatible with many food components, such as starch andimproves rheology of the dough, baking properties, texture, eatingquality and appearance of manufactured breads.

However a literature review and other library searches revealno studies documented on the effect of hydrocolloids on thegluten-free flat breads. The reason could be that flat breads are themain type of breads in the Middle East, including Iran. Thus, theaim of this study was to formulate gluten-free flat bread based onrice flour, corn starch and soy flour using different concentrationsof XG and CMC and to determine the effect of these gums on breadquality.

2. Materials and methods

Corn starch (125 g kg�1 moisture, 30 g kg�1 protein) wasobtained from Farayand Co. (Karaj, Iran); rice flour (98 g kg�1

moisture, 84 g kg�1 protein), with the commercial name ‘Tarom’was purchased from Iran’s local market (Rasht, Iran); defatted soyflour (80 g kg�1 moisture, 45 g kg�1 protein) was obtained fromSoya Sun Co. (Hashtgerd, Iran); pre gelatinized starch was gottenfrom Alborz Starch Co. (Ghazvin, Iran); egg white (70 g kg�1

moisture, 780 g kg�1 protein) was purchased from GolpoodrGolestan Co. (Gorgan, Iran); vegetable oil from Behshahr IndustrialCo. (Tehran, Iran); salt and sugar were obtained from Pars NamakKaveh Co. (Tehran, Iran) the Shazand Sugar Co. (Arak, Iran)respectively; dried instant yeast was purchased from KhuzestanYeast Co. (Khuzestan, Iran). DATEM (Diacetyl Tartaric Acid Ester ofMono- and Diglycerides of fatty acids) and SSL (Sodium StearoylLactylate) from Beldem Co. (Bijgaarden, Belgium), xanthan fromProvisco Co. (Hauptwil, Switzerland) and CMC (Carboxymethyl-cellulose) from Nippon Paper Chemicals Co. (Tokyo, Japan) werealso used.

2.1. Bread preparation

In this work we prepared flat breads based on corn starch andrice flour, similar to an Iranian flat bread ‘‘Barbari’’, which has a

3 cm thickness. Using the ingredients given above, eleven types ofbread were prepared, ten based on formulas 1–10 and one usingthe control formula; six breads with either XG (F1–F3) or CMC (F4–F6), one without either XG or CMC (control), and four with additionof both XG and CMC (F7–F10) (Tables 1 and 2).

Dry ingredients were premixed for 1 min at speed 1 by SpiralMixer M 80-Premium manufactured by Escher Mixers Co.(Schio,Italy); then, oil and water were added and mixed one moreminute at speed 1 and 1 min at speed 2 to enhance mixing. After5 min resting, the dough was divided by hand into 500 g pieces andflattened in trays into sheets of 130 � 330 and 5 mm thickness. Thepieces were proofed at 35 8C for 40 min and, subsequently, bakedat 260 8C for 14 min. The loaves were measured after the bread wascooled down to room temperature. Since aging affects somequality parameters, breads were packed in sealed polypropylenebags and stored at room temperature. The formulae investigated inthis study and their characteristics are presented in Tables 1 and 2.

2.2. Evaluating bread quality

Moisture was measured based on AACC, 44–15 A, and thestaling effects were assessed after 4 and 24, 48 and 72 h of storage[22].

Textural analyses was determined by a Testometric 088-MTCLTexture Analyzer manufactured by Testometric Co. (Rochdale, UK)using a 40 mm diameter aluminum cylinder probe at speed60 mm/min. Crumb firmness was determined on a 10 mm thickpiece from the center of the loaf, compressed up to 50% height.Crumb firmness (%) was evaluated after 4 and 24, 48 and 72 h of

Table 3Moisture (g kg�1) of gluten-free breads formulated with varying levels of CMC and

xanthan during storage at 17–20 8C.

FormulaA Moisture (g kg�1)

Hour 4 Hour 24 Hour 48 Hour 72

Control 326.2 � 1.8e 280.1 � 0.1h 280.6 � 0.8e 261.5 � 0.1b

F1 403.8 � 0.2b 379.1 � 1.3b 374.8 � 0.7c 361.1 � 0.5c

F2 418.7 � 0.8c 409.2 � 0.7d 397.4 � 0.7f 381.8 � 1.2d

F3 448.4 � 0.4d 439.3 � 0.6c 433.5 � 0.3d 416.7 � 0.5e

F4 379.2 � 2.3a 362.1 � 0.6i 354.9 � 0.4b 341.7 � 0.6f

F5 381.3 � 1.2a 364.6 � 1.24a 351.5 � 0.5a 345.1 � 0.4a

F6 400.9 � 3.5b 371.4 � 0.9e 352.9 � 2.2a 345.3 � 0.8a

F7 401.9 � 0.3b 383.1 � 0.6b 374.7 � 0.4c 364.5 � 0.1g

F8 417.4 � 0.7c 397.1 � 0.4f 393.5 � 1.1g 384.2 � 1.1h

F9 446.1 � 0.9d 425.9 � 0.9g 419.6 � 1.2h 413.5 � 0.2i

F10 454.5 � 0.5f 437.9 � 0.9c 435.9 � 2.1k 427.4 � 0.5j

A For formula descriptions see Table 2.

Values are mean � standard deviation of duplicates for each treatment (six repetitions

for each formula).

Means followed by different letters within a column are significantly (P < 0.05)

different.

Table 4Firmness (%) of gluten-free breads formulated with varying levels of CMC and

xanthan during storage at 17–20 8C.

FormulaA Firmness (%)

Hour 4 Hour 24 Hour 48 Hour 72

Control 26.25 � 1.04i 27.42 � 0.43h 27.84 � 0.3e 29.92 � 0.69g

F1 10.27 � 0.27h 18.77 � 1.25i 21.42 � 1.27f 23.18 � 1.19h

F2 9.59 � 0.44ah 12.97 � 1.03af 14.79 � 0.75a 17.54 � 2.83af

F3 5.15 � 0.95b 7.88 � 1.35h 9.37 � 0.54g 9.56 � 0.36i

F4 6.81 � 0.84cg 11.84 � 1.42bf 12.36 � 1.2b 13.75 � 0.54b

F5 6.33 � 0.26ge 12.71 � 0.46af 13.69 � 0.39ac 14.78 � 0.52b

F6 6.07 � 0.54eg 13.44 � 0.7ad 14.7 � 1.25a 15.4 � 2.38be

F7 8.91 � 0.42af 16.16 � 0.29e 19.09 � 0.66h 21.22 � 0.68j

F8 8.5 � 0.2f 16.14 � 0.63e 16.81 � 1.1d 18.84 � 0.52f

F9 7.17 � 0.51c 13.1 � 0.53ad 16.95 � 0.5d 16.27 � 1.53ae

F10 5.74 � 0.39be 11.02 � 1.05b 13.18 � 0.73bc 13.31 � 0.12b

A For formula descriptions see Table 2.

Values are mean � standard deviation of duplicates for each treatment (six repetitions

for each formula).

Means followed by different letters within a column are significantly (P < 0.05)

different.

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–18181814

storage. While testing, the room temperature was 25 8C and therelative humidity 60% [23].

In order to determine bread crumb elasticity (%), a piece ofcrumb was cut as previously described and pressed to the half of itsheight for 1 min. Then, the pressure was removed and after 1 min,the height regained by the compressed piece of crumb wasmeasured. The elasticity values were obtained as the ratio (given aspercentage) of height after compression and recovery to the initialheight [19].

Crumb and crust colors of the fresh bread were measured usinga HunterLab ColorFlex spectrophotometer manufactured byHunterLab Co. (Virginia, USA). Color reading was expressed byhunter values for L, a and b [19].

To evaluate the effect of hydrocolloids on texture and porosityappearance, a piece of bread crumb from the central part of breadwas pressed on a pad and then on a paper; the impressionsobtained represented the original dimensions of the gas cells [24].

Sensory analysis of fresh breads was carried out individually by5 trained assessors in separate booths under white and yellowfluorescent lights (similar to daylight). The characteristics evalu-ated (under crust, crust, form, porosity, softness, chewiness, flavor,overall acceptability) were the most important and crucial sensoryattributes for detecting the quality of flat breads. For eachcharacteristic an evaluation sheet was provided for each assessor.Assessors scored each quality parameter on a scale of 1 (dislikeextremely) to 5 (like extremely). Then, an index was definedconsidering the importance of each property. Each quality wasmultiplied by the defined index and the total sum of these valueswas considered as the final score. In order to evaluate the overallacceptability, a 100 point hedonic scale was used and datacollection was performed in order such that a value of 1 wasassigned to lowest overall acceptability and value of 100 to highestoverall acceptability. Before testing, the samples corresponding toeach treatment were placed randomly on disposable plates with nocolor or odor. The plates were labeled with three-digit codes. Theorder of presentation of the plates to each assessor was different ina random sequence. Bottled water at room temperature was alsoprovided to clean the palate between assessments of each of thesamples.

Dough and bread yield (%): dough mass and bread are expressedin g, prepared from 100 g raw materials [20]; the differencebetween dough mold and the resulting bread prepared from 100 gdough, indicates the weight loss (%).

2.3. Statistical analyses

This research was done in triplicate and all determinations werecarried out in duplicate. The data were analyzed by one-wayAnalysis of Variance (ANOVA), using SPSS 17 statistical package(SPSS Inc., Chicago, IL, USA). The least significant difference (LSD)test was used to determine statistically significant differencesbetween the means. Data from sensory evaluation were subjectedto the Kruskal–Wallis test. The Mann–Whitney U test was used todetermine statistical significance between means. P values < 0.05were considered statistically significant for all comparisons.

3. Results and discussion

3.1. Moisture

Table 3 presents the moisture content of bread formulae. Thegums (XG-CMC) significantly increased bread moisture (P < 0.05),which was also higher in all formulae after 3 days of storagecompared to the control (P < 0.05). F10 had the highest (signifi-cant) moisture content among all the formulae in fresh bread andalso during storage in comparison with the control (P < 0.05). The

increase in the moisture content of the crumb was considered to bedue to the constant dough consistency and the water bindingcapacity of the hydrocolloids, which decreased the degree of crumbdegradation during storage [18].

Hydrocolloids are used in bakery products to control waterabsorption and, consequently, improve dough rheology and shelflife [15]. The xanthan-containing formulae (F1, F2, and F3) had asignificantly higher water content in comparison with the CMC one(at similar concentrations) in fresh and stored bread (P < 0.05).Hence, among the formulae containing either XG (F1–F3) or CMC(F4–F6) per se, F3 had the highest moisture. Adding XG to the CMC-containing formulae significantly increased the moisture level ofthe bread during storage compared to the CMC per se (P < 0.05).Increase in the water content of bread crumb using hydrocolloidshas been reported by Rosell et al. [25] and by Guarda et al. [18].

3.2. Texture evaluation

3.2.1. Firmness

The baked bread formulae were evaluated for firmness; asshown in Table 4, XG and CMC significantly decreased the firmnessof both fresh and stored breads (P < 0.05). Compared to the control,F3 and F10, formulae, resulted in lowest, almost similar values forfirmness of bread (P < 0.05). F3 showed lowest crumb firmnessafter 3 days (P < 0.05). The reason for softness, while maintaining

Table 5Elasticity (%) of gluten-free breads formulated with varying levels of CMC and

xanthan during storage at 17–20 8C.

FormulaA Elasticity (%)

Hour 4 Hour 24 Hour 48 Hour 72

Control 62.5 � 1.00g 59.05 � 0.82d 57.75 � 0.5f 57 � 0.00f

F1 72.10 � 1.02a 65.75 � 0.96e 64.5 � 0.58a 61.2 � 0.96a

F2 73.25 � 0.96ab 67.6 � 0.55a 65.5 � 1.00ab 63.00 � 0.13e

F3 77.00 � 0.00c 72.37 � 0.85b 70.00 � 0.82g 69.60 � 0.55g

F4 70.40 � 1.14h 62.5 � 0.58c 61.00 � 0.00c 60.40 � 0.55a

F5 72.50 � 1.91ab 62.60 � 0.55c 60.74 � 0.37c 60.60 � 0.55a

F6 73.80 � 1.30b 64.25 � 0.96f 63.25 � 0.96j 61.02 � 0.59a

F7 76.40 � 0.71c 69.00 � 1.41gd 66.00 � 0.82bh 63.00 � 1.15e

F8 78.00 � 1.41cf 68.50 � 0.58ad 66.75 � 0.87h 63.50 � 0.58e

F9 79.40 � 1.14f 70.75 � 1.50h 68.80 � 1.47i 67.00 � 1.00d

F10 82.00 � 1.41i 74.75 � 1.50b 70.70 � 0.45g 69.70 � 1.20g

A For formula descriptions see Table 2.

Values are mean � standard deviation of duplicates for each treatment (six repetitions

for each formula).

Means followed by different letters within a column are significantly (P < 0.05)

different.

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–1818 1815

longer shelf life, is that water retention causes higher moisturecontent and, consequently, retro gradation of starch and breadfirming is retarded. Hydrocolloids have a weakening effect on thestarch structure, leading to better water distribution and mainte-nance and also a decrease in the crumb stiffness [15,18].

The effects of hydrocolloids on starch construction andproperties are a result of two opposite phenomena; first, anincrease in rigidity as a result of decrease in the swelling of starchgranules and reduced amylose leaching from the granules and thesecond, a weakening effect on the starch network due toprohibition of the interparticle junction in the amylase chain. Itis perhaps a combination of these two factors that determines theoverall effect on the mechanical properties of bread structure, aneffect that depends on the features of each specific hydrocolloidused for fortification [2,18,19].

As shown in Table 4, F3 had significantly the lowest firmnessamong all formulae containing either XG or CMC (P < 0.05).Considering the effect of gum addition, increase in the concentra-tion of gums, especially xanthan, followed by the rise of moisturecontent, resulted in lower crumb firmness. Hence of the formulaeused, F10 had the lowest crumb firmness (P < 0.05). Water is themost important plasticizer in food, and increase of waterabsorption in bakeries has been reported to augment softnessand decrease bread firmness [2], similar to findings documented byDemirkesen et al. reporting that XG incorporation has a softeninginfluence on gluten-free breads [26].

Lazaridou et al. [19], found that xanthan increased the crumbhardness, contrary to the results of our study, which demonstratethe softening effect of xanthan; these contradictory results canprobably be explained by differences in the methods of breadproduction; we considered the amount of water needed tomaintain consistency, while Lazaridou et al. [19] used formulaewith water levels equal to the concentration level of eachhydrocolloid; F3 was found to have the highest water absorption,which resulted in the lowest bread firmness. The effect XG had onimproving crumb hardness was also reported by Mezaize et al.[20], who investigated the optimization of gluten-free formulae forFrench-style bread.

Hydrocolloids affect the retro gradation level in bread bylimiting both the diffusion and loss of water from bread crumb,indicating that the control of water content and its mobility may bethe key factors, which control crumb firmness in bread [2].

As shown in Table 4, in the xanthan-containing formulae (F1,F2, and F3), while increasing the level of xanthan, decreased thehardness and staling during storage (P < 0.05) whereas none of theCMC-containing formulae (F4, F5, and F6) showed any significantdifference after 3 days of storage. It has been indicated thathardening should take place during storage due to moisture lossand the starch retro gradation phenomena [19]. The amount andrate of starch retro gradation is controlled by the moisture content,which, as it increases, causes a decrease in the hardness of thecrumb [2]; these two (amount and rate) can also slow downamylose or amylopectin polymer associations during storage,thereby reducing occurrence of retro gradation [27]. Of allformulae, F10 followed by F3, both of which had the highestwater content and lower moisture loss, resulted in the minimumfirmness and staling (P < 0.05).

3.2.2. Elasticity

According to the results shown in Table 5, all the formulaecontaining the gums had the higher elasticity compared to thecontrol one, both in fresh and stored breads. Among fresh bread, F3,which included one gum (XG) and, of all the formulae, F10 (XG andCMC) had the most significantly highest crumb elasticity, incomparison to the control (P < 0.05). Among the stored breads,those prepared using formulae F3 and F10 kept the maximum

elasticity during storage (P < 0.05). Lazaridou et al. [19], alsoobserved that the elasticity increased simultaneously withincrease in softness along with the increase in concentration ofhydrocolloids (CMC); however contrary to their results, oursdemonstrated that XG increased the crumb elasticity, disagree-ment in findings which could be due to the differences inproduction methods used, as mentioned earlier.

Increased extensibility by gum incorporation as reported byGujral et al. [28], for chapatti bread prepared using rice wasprobably due to the capability of hyrocolloids to maintain water,and the interactions with water which affect the plasticity of thecrumb and consequently the moisture relocation from the crumbto the crust or because of protein–gum interactions [29].Incorporation of both CMC and XG synergistically increased theelasticity of crumb, compared to using either of them per se(P < 0.05). In the formulae containing both XG and CMC (F7, 8, 9,and 10), by increasing the level of xanthan, loss of elasticitydecreased during storage, being lowest in the bread using F10, withthe highest XG concentration (10 g kg�1) (P < 0.05); howeverformulae with increasing CMC concentrations (F7–F10) were notas efficient.

3.2.3. Crumb and crust color

Crust and crumb color of the gluten-free bread were alsoevaluated using a Hunterlab colorimeter. The L scale ranges from0 (black) to 100 (white); the a scale extends from a negativevalue (green hue) to a positive value (red hue), while the b scaleranges from negative (blue) to positive (yellow). As shown inTable 6, use of CMC and XG resulted in significantly lighter colorfor crumb and crust in all formulae, compared to the control(P < 0.05). F10 and F3 showed the lightest color for crust and Lvalue of crumb was higher for F3 compared with the control(P < 0.05). Except for F4, all formulae had significantly lowercrust color than the control (P < 0.05). No considerabledifferences in crust yellowness (b) were found between thexanthan containing formulae and the control. CMC had a littleeffect on the b value of crust compared with the control(P < 0.05). The influence of gums on the a and b scales of crumbwas not observed in comparison with the control; formula F3was found to have the least values (P < 0.05).

The lightening impact of hydrocolloid can be attributed to theeffect of its addition to the water distribution, which impactedMaillard browning and caramelization [20]. It should be consid-ered that in higher water contents and during dilution ofinteractive materials, the browning reaction decreases [30]. The

Table 6Crust and crumb colors values of fresh gluten-free breads formulated with varying levels of CMC and xanthan.

FormulaA Crust color Crumb color

L a b L a b

Control 54.51 � 1.03a 18.52 � 0.68a 39.32 � 0.78b 69.92 � 1.50a 2.03 � 0.17de 21.62 � 0.51c

F1 61.64 � 1.39de 14.26 � 0.92b 39.36 � 0.37b 71.22 � 0.75b 2.35 � 0.07g 22.72 � 0.13e

F2 63.24 � 0.92f 12.07 � 1.06c 38.34 � 0.90a 73.48 � 1.20de 1.55 � 0.14ab 21.63 � 0.22c

F3 65.17 � 1.40g 12.57 � 0.62cd 39.19 � 0.57b 75.29 � 0.90f 1.40 � 0.07a 20.65 � 0.19a

F4 58.24 � 1.99b 17.83 � 1.14ae 40.49 � 0.64de 73.13 � 0.75cd 1.71 � 0.27c 22.23 � 0.41d

F5 59.36 � 1.78bc 16.37 � 0.90fi 40.99 � 0.36e 72.48 � 1.02c 2.05 � 0.18ef 21.83 � 0.52c

F6 58.93 � 1.06b 17.39 � 0.97ge 40.84 � 1.00de 73.17 � 0.76cd 1.67 � 0.09bc 21.76 � 0.12c

F7 62.97 � 0.97ef 15.21 � 0.68bh 41.04 � 0.29e 73.09 � 0.26cd 1.57 � .012bc 21.98 � 0.26cd

F8 60.56 � 1.65cd 16.56 � 0.96gf 40.44 � 0.24d 72.61 � 0.73c 2.17 � 0.09f 22.78 � 0.35e

F9 63.42 � 0.84f 12.91 � 1.03cd 38.51 � 0.71a 73.76 � 0.50de 2.00 � 0.08de 21.68 � 0.35c

F10 64.72 � 0.53g 15.51 � 0.88hi 39.89 � 0.36c 74.04 � 0.42e 1.89 � 0.02d 21.27 � 0.24b

A For formula descriptions see Table 2.

Values are mean � standard deviation of duplicates for each treatment (six repetitions for each formula).

Means followed by different letters within a column are significantly (P < 0.05) different.

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–18181816

lightening effect of gums on crumb and crust observed in our breadagree with the findings of previous studies [19,20].

Comparing the effects of these two gums at similar concentra-tions, xanthan seemed to have greater influence on crust lighteningand it significantly enhanced the L value for crust, compared withthe CMC-containing formulae (P < 0.05), results similar to those ofLazaridou et al. [19] who obtained greater impression on L valuefor crumb and a significant increase in crumb lightness byincluding xanthan (P < 0.05). However increasing the CMCconcentration caused no significantly lighter crumb; in the 2007studies by Lazaridou et al. [19], scores of the above-mentionedfeatures decreased compared with the control; this dissimilaritymay have been caused by of some factors like formulation,production method or even the kind of bread, a score reductionmore evident by xanthan addition. CMC-containing formulae had ahigher score for crust than the XG-containing formulae at the sameconcentration, with scores increasing with increases in concentra-tions (P < 0.05). Similar to findings of the study by Lazaridou et al.[19], in our study, b value for crust in CMC-containing formulaewas significantly higher than the control and XG-containingformulae (P < 0.05).

3.3. Sensory evaluation

Results in Table 7 show that all gluten-free formulae containinghydrocolloids received significantly higher scores, compared to thecontrol (P < 0.05). Among all formulae (those with without or withboth gums), F3 and F10 gained highest scores, respectively, withthe latter obtaining the highest acceptability among them(P < 0.05).

Table 7Sensory characterization of fresh gluten-free breads formulated with varying levels of

FormulaA Under crust Crust Form Porosity

Control 3.11 � 0.40c 4.13 � 0.70a 2.61 � 0.20a 3.33 � 1.03

F1 4.16 � 0.28a 8.27 � 0.33b 3.83 � 0.28b 6.67 � 1.37

F2 4.87 � 0.18b 8.84 � 0.30b 4.80 � 0.30cd 7.90 � 0.74

F3 4.87 � 0.18b 9.76 � 0.22cde 5.00 � 0.00d 7.27 � 0.43

F4 4.60 � 0.55ab 8.32 � 0.33b 4.27 � 0.37bc 8.00 � 0.00

F5 4.73 � 0.28b 8.96 � 0.22cd 4.51 � 0.21c 9.00 � 0.00

F6 4.87 � 0.18b 9.44 � 0.22cd 4.73 � 0.28cd 8.60 � 0.55

F7 4.67 � 0.33b 8.88 � 0.71bc 4.80 � 0.30cd 8.00 � 0.00

F8 5.00 � 0.00b 8.72 � 0.22bd 4.40 � 0.37bc 9.40 � 0.55

F9 5.00 � 0.00b 9.84 � 0.00e 5.00 � 0.00d 8.40 � 0.55

F10 5.00 � 0.00b 10.00 � 0.00e 5.00 � 0.00d 10.00 � 0.00

A For formula descriptions see Table 2.

Means followed by different letters within a column are significantly (P < 0.05) differe

A higher value indicates higher overall acceptability.

It has been documented that gums usually improve thecohesion of starch granules, producing the required breadstructure, mouth feeling and loaf volume, which are comparablein quality to those of the commonly accepted breads [14].Lazaridou et al. used CMC, pectin, xanthan, agarose and b-glucanto make gluten-free breads, all of which increased the acceptabilityof bread, compared with the control, with CMC and XGdemonstrating better effects [19]. Toufeili et al. [31] also evaluatedeffects of Microcrystallin Cellulose (MC), gum arabic and eggalbumen on the sensory properties of gluten-free flat breadsformulations. MC and egg albumen were identified as the majordeterminants of the sensory quality [31].

Furthermore, Demirkesen et al. [26] reported higher consumerpreference, by adding xanthan, guar, locust bean, HPMC, pectin,xanthan-guar and xanthan-locust bean compared with the control,with xanthan producing the better values [26]. Our results showedthat the highest score in the formulae (F1–6) containing each gumper se, was for F3. Xanthan improved the structure of gluten-freebreads and made them comparable in attributes with mostcommercial breads [14]. In the formulae containing both XG andCMC (F7–10), increase in concentration of gums, especiallyxanthan, strongly increased the total score, with F10 being scoredhighly by the assessors (P < 0.05), findings which confirmed theresults obtained by Gambus et al. [10], Ozboy [14] and byDemirkesen et al. [26].

3.4. Porosity appearance

Slices of the breads’ crumbs, from the center of bread, are shownin Fig. 1. It can be observed that gas cells in the breads containing

CMC and xanthan.

Softness Chewiness Flavor Overall score

a 5.41 � 1.17a 3.22 � 1.15h 28.48 � 1.33g 50.31 � 1.13d

b 9.50 � 0.91b 6.00 � 0.84a 35.73 � 2.42a 74.16 � 1.06e

bc 11.60 � 0.41cd 7.69 � 0.33b 37.85 � 0.69b 83.50 � 1.05a

b 14.05 � 0.33fg 9.09 � 0.28c 44.08 � 0.84c 94.00 � 0.64b

bc 11.73 � 0.44d 5.73 � 0.37a 36.90 � 1.33ab 79.55 � 0.98f

d 13.20 � 0.85ef 7.07 � 0.37b 41.41 � 0.84d 88.90 � 1.51c

cd 13.15 � 0.38e 7.74 � 0.36b 43.47 � 0.00c 92.00 � 0.8 g

bc 10.80 � 0.41bc 7.07 � 0.37b 38.70 � 1.24b 82.91 � 0.67a

de 11.85 � 0.63d 7.74 � 0.36b 41.42 � 0.84d 88.53 � 1.12 c

cd 12.45 � 1.00de 9.60 � 0.36c 44.08 � 0.84c 94.38 � 1.24b

e 14.25 � 0.00g 9.60 � 0.36c 44.39 � 0.84c 98.24 � 0.48h

nt.

Fig. 1. Effect of hydrocolloids on porosity appearance of gluten-free breads.

Table 8Technological characteristics (%) of gluten-free breads formulated with varying

levels of CMC and xanthan.

FormulaA Dough yield (%) Weight loss (%) Bread yield (%)

Control 155.5 � 0.73d 16.71 � 0.53j 133.9 � 00.86f

F1 165.60 � 0.00ae 13.78 � 1.56a 147.9 � 02.68ac

F2 172.1 � 00.39b 12.67 � 1.03ab 155.60 � 1.84g

F3 177.20 � 0.07i 11.60 � 0.55bc 162.1 � 01.00b

F4 163.40 � 0.37f 13.25 � 1.83a 146.80 � 3.10cd

F5 164.10 � 0.62g 13.14 � 1.07ae 147.60 � 1.82acd

F6 165.00 � 0.13e 12.86 � 1.07abef 148.90 � 1.83ad

F7 166.30 � 0.39ac 11.75 � 1.28bcfg 151.90 � 2.21e

F8 166.90 � 0.45c 11.75 � 1.67bcfgh 152.5 � 2.88e

F9 172.50 � 0.13b 11.11 � 1.05cghi 158.70 � 1.88h

F10 173.40 � 0.00h 9.89 � 1.45i 161.70 � 2.61b

A For formula descriptions see Table 2.

Values are mean � standard deviation of duplicates for each treatment (six repetitions

for each formula).

Means followed by different letters within a column are significantly (P < 0.05)

different.

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–1818 1817

CMC are bigger than those in breads containing xanthan, whichhad compacted crumbs. In the breads including both gums,porosity improved by increasing the CMC level. As observed inTable 7, in sensorial assessment, higher scores were obtained forporosity using CMC, compared to the XG ones (at similarconcentrations). The highest value was obtained for F10. Lazaridouet al. [19] and Mezaize et al. [20] reported that CMC resulted inmore porosity, improving dough development and gas retentionand larger cell size.

Cellulose-derivatives such as CMC, HPMC and MC containhydrophilic and hydrophobic groups, which provoke otherproperties, including interfacial activity inside the dough structureduring proofing and construction of gel networks during the breadmaking procedure. Such complex structures increase viscosity andreinforce the boundaries of the gas cells growing in the dough andsubsequently increase the gas retention throughout baking [19]. Ithas been suggested that XG addition makes the dough too rigid andstiff for gases to slip in and produce voluminous breads [19,20].

3.5. Dough and bread yield and weight loss

Xanthan and CMC resulted in increased dough yield (Table 8).Compared to other formulae, F3 showed significantly greaterdough yield (P < 0.05). Xanthan, because of better water absorp-tion, increased dough yield, in comparison with CMC; thecombination of both XG and CMC led to higher dough yield,

compared to using each per se (P < 0.05). All the formulaeexhibited significantly lower weight loss, compared with thecontrol, with F10 having the lowest (P < 0.05). Moisture measure-ment (Table 3) shows stronger impression of gums, especiallyxanthan on water retention, which led to better weight retention,findings similar to those of Gambus et al. [10], who reported thatxanthan accretion caused reduction in weight loss. F3 and F10 did

M. Mohammadi et al. / Journal of Industrial and Engineering Chemistry 20 (2014) 1812–18181818

not differ significantly and showed the highest bread yield(P < 0.05), which could be a result of increased water absorptionand less weight loss, due to xanthan addition, results in agreementwith those of Gambus et al. [10].

4. Conclusions

The effects of XG and CMC on bread quality parameters wereevaluated in order to formulate suitable gluten-free bread and ourresults showed that xanthan had more impact on increasingmoisture and that F3 (15 g kg�1 XG) and F10 (10 g kg�1

CMC + 10 g kg�1 XG) had the lowest hardness. In the formulaecontaining both XG and CMC (F7–10), increase in XG concentrationwas more effective in decreasing hardness and increasingelasticity, in both fresh and stored breads. Xanthan had moreinfluence on increasing L value for crumb and crust. In sensorialassessment, F10 and F3 gained the highest acceptability score. CMCcaused bigger gas cells and increasing its concentration led tobetter crumb porosity appearance. F3 and F10 had the highestdough yield and lowest loss weight, respectively, and both showedthe maximum bread yield. Xanthan seems to be the besthydrocolloid that improved gluten-free breads, demonstratingthat F10, and F3 can be used to produce good quality gluten-freeflat bread, bread that is acceptable, especially for the consumer,predisposed to the side effects of gluten.

Acknowledgements

The data were obtained from the results of an approvedresearch project (P/25/47/7137) of the National Nutrition and FoodTechnology Research Institute, Iran. The authors would like tothank the Cereal Research Center of Ministry of Industry, Mine andTrade of Iran for provision of the equipment required formeasurement.

References

[1] J. Garooni, in: M.A. Azizi, M. Hojati (Eds.), Flat Bread Technology, AndishmandPublication, Tehran, 2004, pp. 65, 75.

[2] K.A. Elke, F. Dal Bello, The Gluten Free Cereal Products and Beverages, Elsevier Inc.,2008.

[3] H. Goesaert, K. Brijs, W.S. Veraverbeke, C. Courtin, K. Gebruers, J.A. Delcour, TrendsFood Sci. Technol. 16 (2005) 12.

[4] A.A. Anton, S.D. Artfield, Int. J. Food Sci. Nutr. 59 (2007) 11.[5] A. Sabatino, G.R. Corazza, Lancet 373 (2009) 1480.[6] H.P. Sivaramakrishnan, B. Senge, P.K. Chattopadhyay, J. Food Eng. 62 (2004) 37.[7] R. Hamaker Bruce, Technology of Functional Cereal Products, Woodhead Pub-

lishing Limited, 2008.[8] A. Basman, H. Koksel, P.K.W. Ng, Eur. Food Res. Technol. 215 (2002) 419.[9] P.D. Ribotta, S.F. Ausar, M.H. Morcillo, G.T. Perez, D.M. Beltramo, A.E. Leon, J. Sci.

Food Agric. 84 (2004) 1969.[10] H. Gambus, M. Sikora, R. Ziobro, Acta Sci. Pol. 6 (2007) 61.[11] D. Curic, D. Gabric, I. Bauman, D. Tusak, D. Novotni, Agric. Conspec. Sci. 72 (2007)

227.[12] A. Houben, A. Hochstotter, T. Becker, Eur. Food Res. Technol. 235 (2012) 195.[13] E. Gallagher, T.R. Gormley, E.K. Arendt, J. Food Eng. 56 (2003) 153.[14] O. Ozboy, Nahrung/Food 46 (2002) 87.[15] Z. Kohajdova, J. Karovicova, Chem. Pap. 63 (2009) 26.[16] C. Collar, P. Andreu, J.C. Martinez, E. Armero, Food Hydrocolloids 13 (1999) 467.[17] G. Lorenzo, N. Zaritzky, A. Califano, J. Cereal Sci. 48 (2008) 224.[18] A. Guarda, C.M. Rosell, C. Benedito, M.J. Galotto, Food Hydrocolloids 18 (2004)

241.[19] A. Lazaridou, D. Duta, M. Papageorgiou, N. Belc, C.G. Biliaderis, J. Food Eng. 79

(2007) 1033.[20] S. Mezaize, S. Chevallier, A. Le Bail, M. De Lamballerie, J. Food Sci. 74 (2009) 140.[21] C. Onyango, G. Unbehend, M.G. Lindhauer, Food Res. Int. 42 (2009) 949.[22] AACC International, Approved Methods of the American Association of Cereal

Chemists, 10th ed., The Association, St. Paul, MN, 2000.[23] A. Sadeghi, F. Shahidi, A. Mortazavi, A. Koocheki, M. Mohebbi, World Appl. Sci. J. 2

(2007) 490.[24] A.C.B. Lopez, A.J.G. Pereira, R.G. Junqueira, Braz. Arch. Biol. Technol. J. 47 (2004) 63.[25] C.M. Rosell, J.A. Rojas, C. Benedito de Barber, Food Hydrocolloids 15 (2001) 75.[26] I. Demirkesen, B. Mert, G. Sumnu, S. Sahin, J. Food Eng. 96 (2010) 295.[27] I.G. Mandala, K. Sotirakoglou, Food Hydrocolloids 19 (2005) 709.[28] H.S. Gujral, M. Haros, C.M. Rosell, J. Food Eng. 65 (2004) 89.[29] A. Mandala, D. Karabela, A. Kostaropoulos, Food Hydrocolloids 21 (2007) 1397.[30] H. Fatemi, Food Chemistry, Enteshar Sahami Co., Tehran, 2010.[31] I. Toufeili, S. Dagher, S. Shadarevian, A. Noureddine, M. Sarakbi, M.T. Farran, Cereal

Chem. 71 (1994) 594.