EFFECT OF MINERAL FORTIFICATION ON RHEOLOGICAL PROPERTIES OF WHOLE WHEAT FLOUR

EFFECT OF MINERAL FORTIFICATION ON RHEOLOGICALPROPERTIES OF WHOLE WHEAT FLOUR

SAEED AKHTAR1,4, F.M. ANJUM2, SALEEM-UR–REHMAN2

and MUNIR A. SHEIKH3

1University College of AgricultureBahuaddin Zakariya University

Multan, Pakistan

2National Institute of Food Science and TechnologyUniversity of Agriculture

Faisalabad, Pakistan

3Department of ChemistryUniversity of Agriculture

Faisalabad, Pakistan

Received for Publication May 18, 2008Accepted for Publication September 15, 2008

ABSTRACT

This study was aimed to evaluate the rheological changes that take placein the dough as a result of addition of elemental iron, ferric sodium ethylene-diaminetetraacetate, zinc sulphate and zinc oxide in various combinationsto whole wheat flour (WWF), packaged in polypropylene woven bags andtin boxes and stored for a period of 60 days under ambient and controlledconditions of temperature and relative humidity. Water absorption (WA)capacity, dough development time (DDT) and dough stability time (DS) of thefortified WWF were measured by farinographic method, and peak viscositywas assessed by viscographic analyses. WA capacity and DDT of floursincreased during storage. Fortification significantly (P < 0.05) affected WA,DDT, DS and viscographic characteristics of the flours. Packaging materials(P < 0.05) influenced WA, DDT and DS, while storage condition had onlyaffected viscographic properties of the flours.

4 Corresponding author. TEL: +92-333-6106099; FAX: +92-61-9210098; EMAIL: [email protected]

Journal of Texture Studies 40 (2009) 51–65.© 2009, The Author(s)Journal compilation © 2009, Wiley Periodicals, Inc.

51

PRACTICAL APPLICATIONS

The success of any fortification program depends on the stability ofmicronutrients and food to which they are added. Exposure of the fortificantsto any of the physical and chemical factors including heat, moisture, air, orlight and acid or alkaline environments during food processing, packaging,distribution or storage affects their stability. The rheological properties ofdough made from fortified flours determine the quality of the fortified endproduct. Changes in rheological properties as a result of the incorporation offortificants in the flour, its storage under variable conditions and length of timemight have an effect on quality, cost and nutrition of the product.

KEYWORDS

Fortification, minerals, rheology, storage, whole wheat flour

INTRODUCTION

Iron-deficiency anemia is the most common nutritional disorder in bothdeveloped and developing countries. It affects two billions of people world-wide (Mawajdeh et al. 1996). A high prevalence of iron deficiency in adoles-cents belonging to lower socioeconomic group was reported. Iron deficiencywas more frequent than anemia in adolescent girls than boys in Pakistan (Aghaet al. 1992). Micronutrient fortification is regarded as the most effectivemethod for reducing prevalence of nutritional iron and zinc deficiency (Hansenet al. 2005).

Whole wheat flour (WWF) is the staple food of Pakistani people, and theaverage intake of it is 318 g per person/day. Forty-five percent of the totalenergy intake is derived from this source (OMNI 1996). Fortification of WWFmay influence various attributes of the flour and its products. Several studieshave demonstrated the effect of addition of micronutrients on chemical com-position and microbiological characteristics of the flour (Rosado et al. 2005;Akhtar et al. 2008).

The rheological properties of dough are related to the quality of the flourand its finished products. The changes in chemical composition as a result ofmineral fortification might have some effect on rheological characteristicsof the flours. These properties of dough made from fortified flours are oftremendous significance with respect to the dough yield and quality of theend product. The water absorption (WA) of the flour is associated with yield,

52 S. AKHTAR ET AL.

a major concern of the producer of the baked products, while dough develop-ment time (DDT), dough stability time (DS) and peak viscosity (PV) directlydictate the quality of the end product.

The rheological behavior of WWF dough also provides the basis forunderstanding the handling properties of dough in a bakery, and any change inthe chemical composition of flour might have a profound impact on the qualityof the product. Amylograph continuously measures the resistance to stirring ofstarch slurry, while temperature of the suspension is raised at a constant rate.The changes in the viscosity of starch slurry that have occurred as a result ofamylase action during rise of temperature are depicted on graphs. Viscographconsistencies of starches decrease due to degradation of the starch by theaction of high amylase activity (Lorenz and Kulp 1981).

The present study focused on evaluation of the changes that might takeplace in WA, DDT, dough stability and PV of WWF as a function of mineralfortification, storage time, type of packaging materials and storage conditionsof the fortified flours.

MATERIALS AND METHODS

Materials

A popular Pakistani wheat variety, Inqulab 91 was used for the pro-duction of WWF and was procured from the Post-Graduate AgriculturalResearch Station, University of Agriculture, Faisalabad, Pakistan. Mineralpremix containing elemental iron, ferric sodium ethylenediaminetetraacetate(NaFeEDTA), zinc sulphate (ZnSO4) and zinc oxide (ZnO) was used forfortification. The iron fortificants were obtained from Micronutrient Initiative,Ottawa, Ontario, Canada, and zinc fortificants were supplied by Fortitech Inc.(New York, NY).

Fortification, Packaging and Storage of WWF

The micronutrient mixture was added to WWF as per treatment combi-nation given in Table 1 to yield fortified flours. To ensure the proper mixing ofthese minerals in the flour, the premix was first blended with WWF at 1:4(w/w) with a portion of WWF, and this blend was added to the wheat flour. Avolumetric screw type feeder was used to add the premix to the flour. Toachieve homogeneous flour and to ensure the level of fortification claimed,samples of fortified flours were collected during mixing at different times, andaliquots were assayed for iron and zinc concentration. This process was carriedout until the concentration was similar in the samples taken from varioussections of the flours. The fortified flour samples (5 kg each) were packaged in

53RHEOLOGY OF MINERAL FORTIFIED FLOUR

polypropylene woven bags and tin boxes (12 ¥ 10 ¥ 8 in.) and stored for 60days under controlled storage condition (CSC) of temperature (23–25C) andrelative humidity (45–55%) and under ambient storage condition (ASC),representing the hottest season, i.e., during June and July (35–42C). The tem-perature and relative humidity were recorded daily (morning and evening)both in CSC and ASC (Akhtar et al. 2008).

Proximate Composition

The following methods were used to determine proximate composition offortified and unfortified WWF samples during storage: drying at 105C for 24 hfor moisture (method 925.098); incineration at 550C for ash (method 923.03);defatting in a Soxhlet apparatus with 2:1 (v/v) chloroform/methanol for lipids(method 920.39C); and micro Kjeldahl for protein (N ¥ 6.25) (method 960.52)(AOAC 1990). Nitrogen-free extract (NFE) was determined by difference.NFE is basically the carbohydrate content and is usually determined by thedifference from the original sample minus the moisture, protein, crude fat andmineral content, with their contents calculated at the same moisture level(Akhtar et al. 2008).

Physical Dough Properties

WA, DDT and DS of fresh and stored fortified WWF were determined byrunning the flour samples through Brabender farinograph (National Mfg. Co.,Lincoln, NE) equipped with a 50-g bowl capacity, according to the standardAmerican Association of Cereal Chemists (AACC) methods (Method No.54-21; AACC 2000).

TABLE 1.LEVELS AND COMBINATIONS OF IRON AND ZINC (mg/kg)

USED IN WHEAT FLOUR

Treatments NaFeEDTA Elemental iron ZnSO4 ZnO

T0 – – – –T1 60 – 30T2 40 – – 20T3 – 40 30T4 – 40 – 20

NaFeEDTA, sodium ethylenediaminetetraacetate; ZnSO4, zincsulphate; ZnO, zinc oxide, T0, unfortified flour; T1, fortified withNaFeEDTA + zinc sulfate; T2, fortified with NaFeEDTA + zincoxide; T3, elemental iron + zinc sulfate; T4, elemental iron + zincoxide.

54 S. AKHTAR ET AL.

Viscographic Studies

Diastatic activity of fortified and unfortified WWF was estimated usingBrabender Amylograph (National Mfg. Co., Lincoln, NE) as outlined in AACC(2000) (Method No. 54-40 A). A buffer at pH 5.4 � 0.05 containing anhydrousdisodium phosphate and citric acid monohydrate was prepared by taking 14.8and 10.3 g of each, respectively, and volume was made to 1,000 mL. The dilutedbuffer solution (46 mL) was used to make a volume of 460 mL with distilledwater. Eighty grams of flour sample (14 g/100 g water basis) was mixedthoroughly in 460 mL of diluted buffer solution until a lump-free suspensionwas obtained. This suspension was then heated in an amylograph bowl by givinga temperature rise of 1.5C/min during this heating process. Change in theviscosity of the suspension was continuously measured and recorded on thegraph. The viscosity was expressed as Brabender Unit (BU).

Statistical Analysis

Data were statistically analyzed using analysis of variance, split plottechnique and four-factor factorial as described by Steel et al. (1996). Duncan’sMultiple Range Test was employed to assess the difference between means(Duncan 1952). Significance was defined at P � 0.05. Each experiment wasrepeated twice (three determinations), and the values are reported as means.

RESULTS AND DISCUSSION

WA Capacity

WA capacity is the amount of water needed to obtain dough of a certainwork input and is mainly related to the dough yield. Difference in WA of floursdefines the variation in the cost of the end product. Storage conditions of thefortified flours did not show a significant effect on WA (Table 2).

Addition of iron and zinc in WWF significantly (P < 0.05) affectedWA of fortified flours. Incorporation of sodium ethylenediaminetetraacetate(NaFeEDTA) with ZnSO4 in WWF showed no effect on WA, while the flourcontaining NaFeEDTA and ZnO manifested a significant effect on WA. Theresults revealed that the concentration of NaFeEDTA did not affect this phy-sical dough property, and the type of zinc fortificants primarily inducedthis incremental effect (Fig. 1A). Conversely, elemental iron significantlyincreased the WA of fortified flours, and zinc salts seemed likely to haveno effect on WA when used with elemental iron (Fig. 1A). Obviously, thesefindings indicate that the presence of ZnO and elemental iron in the floursincreased the WA of such flours. ZnSO4 and NaFeEDTA are more soluble than


ZnO and elemental iron, and the tendency of these salts to absorb water maybe a contributing factor toward these differences in WA.

Packaging materials had shown a significant effect on the WA ofthe fortified flours (Table 2). Flours stored in bags exhibited higher WA ascompared with the flours stored in tin boxes, irrespective of treatment types,storage periods and storage conditions (Fig. 1C).

TABLE 2.MEAN SQUARES FOR RHEOLOGICAL PROPERTIES OF DIFFERENT FORTIFIED

WHOLE WHEAT FLOURS

Source of variation Mean square

Waterabsorption

Doughdevelopmenttime

Doughstability

Peakviscosity

Storage condition (A) 0.689NS 0.3125NS 2.0098NS 271,445*Days (B) 12.561* 30.1625* 42.6926* 24,205,715*Packaging (C) 7.783* 2.1125* 4.4180* 32,805NS

Treatment (D) 7.012* 6.3125* 11.0073* 795,170*B ¥ C 2.332NS 0.9875* 1.2545NS 9,855NS

Degrees of freedom 120Error 0.537 0.2027 0.4521 34,647

Variables being significant are presented in the table. Nonsignificant interactions are not given in thetable.* Significant at P � 0.05.NS, nonsignificant.

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T0 T1 T2 T3 T4

Fortified flour

Wat

er a

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)

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68

0 30 60

Storage time (days)

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68

Bags Boxes

Packaging material

Wat

er a

bsor

ptio

n (%

)

A CB

FIG. 1. EFFECT OF FORTIFICATION ON WATER ABSORPTION (%) OF DIFFERENTFORTIFIED WHOLE WHEAT FLOURS

(A) Water absorption of fortified flours during storage, irrespective of treatment types, packagingmaterials and storage conditions. (B) Water absorption of fortified flours in different packaging

materials irrespective of treatment type, storage time and storage conditions. (C) Water absorptionof different fortified flours irrespective of storage time, packaging materials and storage conditions.

T0, unfortified flour; T1, fortified with NaFeEDTA + zinc sulfate; T2, fortified withNaFeEDTA + zinc oxide; T3, elemental iron + zinc sulfate; T4, elemental iron + zinc oxide.

56 S. AKHTAR ET AL.

Packaging material acts as a moisture barrier to retain the water level ofthe stored samples. The WWF samples used in the present study contained lessmoisture as compared with the WWFs prepared from commercially processedwheat. Tin boxes as a storage material retained low moisture in the flours,effectively stabilizing the moisture content and keeping it as low as possiblewhen compared with polypropylene woven bags. The marginal difference inWA of flours in different packaging materials during storage may be ascribedto the progressive change in temperature and relative humidity. Temperatureand relative humidity are two important factors affecting the moisture level ofthe flour, and the ability of the package to prevent undesirable changes inmoisture level confirms its suitability as a good packaging material duringstorage of fortified flours.

Periodical analysis of flours revealed a significant (P < 0.05) progressiveincrease in WA during storage. The highest WA was observed in flour sampleswhen tested after 60 days of storage, while fresh samples manifested minimumwater absorption (Fig. 1B).

The fortificants are the mineral salts, which possess hygroscopic charac-teristics and are assumed to exert a prominent influence on the WA of the floursamples. The WWF was produced from the freshly harvested wheat without anyconditioning or tempering and contained less moisture, resulting in high WAof these flour samples. The ambient storage condition manifested a highertemperature with minimum humidity (months of May and June), and the storedflours further dried up over this period, resulting in higher WA capability. Thepotential of the fortificants to absorb moisture and the initial low moisture ofthe flours might have an effect on the WA. A previous study demonstrated anincrease in WAupon addition of minerals to dough, suggesting that the mineralshave the tendency to absorb more water (Rehman et al. 1988).

Changes in rheological properties of the flour are indicative of thequality end use product and also help in understanding the handling proper-ties of dough during processing. Moreover, they may even predict the qualityof the bakery products (Sollars and Rubenthaler 1975). The results of WAobtained in the present study are higher than the results already reported withvalues ranging from 53 to 60% as compared with the values 60.7–63.8%obtained in the present study (Borghi et al. 1996). This difference might beattributed to a number of reasons like genetic character of the wheat used,packaging materials, storage conditions and type and level of the iron andzinc fortificants.

Another study confirmed that the differences in WA may be mainly aresult of the greater number of hydroxyl groups that exist in the fiber structureand allow more water interaction through hydrogen bonding (Rosell et al.2001). Changes in WA capacity of fortified flours may be attributed to thechanges in moisture content, concentration of bran, protein content, damaged


starch and enzymatic activity which might be affected directly or indirectlythrough the incorporation of different fortifiers.

DDT

DDT is the time required to reach the maximum consistency. There wasa significant (P < 0.05) effect of fortificants on DDT. Changes in DDT werenot observed in relation to the storage conditions of the fortified flours.However, storage time, type of packaging material and addition of fortificantsexhibited visible (P < 0.05) changes in DDT of such flours (Table 2). Additionof minerals to WWF reduced the DDT. However, WWF seemed to be moresusceptible to elemental iron as compared with NaFeEDTA for this rheologicalproperty (Fig. 2A). Zinc salts were shown to exert no effect on DDT of theflours as compared with elemental iron. The highest DDT was found to be7.34 min for the control (unfortified flour), and 6.25 min DDT was recorded inflours containing elemental iron with ZnO (Fig. 2D). The ability of elementaliron and ZnO to influence the rheology of WWFs was larger than that ofNaFeEDTA and ZnSO4.

DDT of the fortified flour samples increased by 22.5% during storagefor 2 months when tested, irrespective of treatment type, storage conditionand packaging material (Fig. 2A). Interactive effect of packaging material andstorage time on DDT was found to be significant as the flours stored in bagsfor 60 days showed higher DDT as compared with the flours stored in tin boxesfor the same storage period; nevertheless, these differences were marginal at0 and 30 days of storage (Fig. 2B). Similarly, packaging material did not revealany significant difference in relation to DDT of fortified flours when the effectwas observed irrespective of storage conditions, treatment types and storageperiods (Fig. 2C).

The changes in DDT of such flours as a result of fortification with zincand iron may be attributed to the interaction of each type of fortificant, withprotein of the flour samples forming complexes, which ultimately affected thegluten content of the dough, manifesting the variability in DDT.

In another study, various levels of minerals were added to the flours ofdifferent extractions rates (60–75%). The flours of 75% extraction rate dis-played more water absorption as compared with those of 60% extraction rate(Rehman et al. 1988). The extent of increase in DDT was high in the case ofwheat and rice bran blends.

The shorter DDT might be associated with reduced farinographic stabilityand high degree of softening (Pomeranz et al. 1968). It was further reportedthat excessively higher DDT might be a result of the presence of higherproportion of bran particles in WWF, which may interfere with the quickerdevelopment of the gluten (Haridas et al. 1986). Preferential absorption of

58 S. AKHTAR ET AL.

water by some other constituents rather than gluten might have also contrib-uted to the longer DDT (Haridas et al. 1986; Corbellini et al. 1999). Severalstudies substantiated an increase in DDT upon the addition of micronutrientsand related factors; the authors confirmed that DDT and stability of dough ofBritish wheat varieties ranged from 3.5 to 17.5 min, and these values wererelatively higher than those of the wheat varieties obtained in the present study.The higher DDT in British wheat varieties may be related to their proteincontent, which is generally higher than that of the wheat varieties of Indian

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Fortified flour

Dou

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Dou

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Storage time (days)

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Storage time (days)

Dou

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in)

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D

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C

FIG. 2. EFFECT OF FORTIFICATION ON DOUGH DEVELOPMENT TIME (min) (DDT) OFDIFFERENT FORTIFIED WHOLE WHEAT FLOURS

(A) DDT of fortified flours during storage, irrespective of treatment types, packaging materials andstorage conditions. (B) DDT of fortified flours during storage, irrespective of treatment types and

storage conditions. Interactive effect packaging materials (� bags, � boxes) and storage time.(C) DDT of fortified flours in different packaging materials irrespective of treatment type, storage

time and storage conditions. (D) DDT of different fortified flours irrespective of storage time,packaging materials and storage conditions.



subcontinent. A significant improvement in DDT, WA and DS on addition ofiron fortificants to flours was also reported (Bakr 1997; Rehman et al. 1997).

Addition of various iron salts to wheat flour had a marginal effect onthe water absorption of flour. Addition of iron as ferrous sulphate and EDTAincreased the WA gradually by about 1–1.5% and 2%, respectively, whereasthere was no effect of iron addition in the form of ferrous fumerate. Additionof iron as ferrous sulphate increased the DS values, whereas iron as ferrousfumarate and ferrous EDTA marginally reduced the same. The PV and cold PValso increased with an increase in the level of premix (Sudha and Leelavathi2008).

DS Time

DS is the time in minutes during which the curve remains on 500 BU line.Difference in storage temperature and relative humidity did not predominantlyinfluence the DS of fortified flours; nevertheless, marginal differences in DSwere observed (Table 2). WWF fortified with NaFeEDTA and zinc fortificants(ZnSO4 and ZnO) did not show significant differences (P < 0.05) in DS ascompared with the control, but elemental iron was able to act as a compoundmanifesting a significant increment in DS with either source of zinc (Fig. 3C).

Figure 3A illustrates a concomitant significant decrease in DS of fortifiedflours as a result of storage of fortified flours for 60 days, i.e., 8.75 and 12.65%decrease at 30 and 60 days of storage, respectively. The flour samples packedand stored in bags exhibited higher DS as compared with the flours packed andstored in tin boxes (Fig. 3B).

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Storage time (days)

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Fortified flour

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Packaging material

CBA

FIG. 3. EFFECT OF FORTIFICATION ON DOUGH STABILITY TIME (min; DS)OF DIFFERENT FORTIFIED WHOLE WHEAT FLOURS

(A) DS of fortified flours during storage, irrespective of treatment types, packaging materials andstorage conditions. (B) DS of fortified flours in different packaging materials irrespective of

treatment type, storage time and storage conditions. (C) DS of different fortified flours irrespectiveof storage time, packaging materials and storage conditions.


60 S. AKHTAR ET AL.

This has clearly indicated that elemental iron acted differently on thisrheological characteristic of dough made from fortified flours as comparedwith the dough of flours prepared from NaFeEDTA. Zinc fortificants aloneseemed to have no effect on the rheology of the fortified flours. Previousstudies confirmed that DS and DDT were not affected because of storage ofWWF (Leelavathi et al. 1984a). Cenkowski et al. 2000 explained the effect ofstorage on rheological properties of flour and stated that the storage of flour upto 30C caused changes in dough rheological parameters, indicating a dough-strengthening effect. The storage of flour at 40C resulted in tight, inextensibledough that was difficult to process in bakeries. Lukow et al. (1995) substan-tiated an increase in farinograph stability and improvement in dough handlingquality during 15 months of storage at low temperature.

The changes in flour at temperature during storage generally become lesspronounced. Leelavathi et al. (1984b) demonstrated that the storage time ofWWFs had no effect on the DDT and DS. In a similar study, Ziaullhaq et al.(2004) found a decreasing trend in DS of mineral-fortified flours duringstorage. In another study, DS, which indicates the dough strength, decreasedsignificantly from 8.5 to 4 min and 7.0 to 3.5 min in the case of oat and barleyblends, respectively, whereas the extent of decrease was relatively marginal inthe case of wheat and rice bran blends (Sudha and Leelavathi 2008). Theincrease in DDT of flours in storage may be a result of the changes in proteinquality and content of the flours.

Viscographic Characteristics

Viscosity of flour paste increases as gelatinization of starch starts, butat that time, amylases begin to break down the paste, rapidly decreasing theviscosity. This dual process indicates the reaction of dough during baking andis generally shown as a curve. Contrary to the farinographic changes in WWFsduring the present research, storage conditions of such flours exerted a sig-nificant (P < 0.05) effect on viscographic properties of these flours (Table 2).Findings of the present study revealed that elemental iron with ZnSO4 and ZnOacted differently and had significantly reduced PV of fortified flour samples.NaFeEDTA did not affect the PV of the fortified flour samples with eithersource of zinc (Fig. 4C).

It is evident from Fig. 4A that a significant increase (P < 0.05) in PV wasobserved as a function of storage time, and the values for PV of fortified floursalmost doubled at the end of the storage of 2 months. In case of viscographicanalysis, the storage condition showed a significant effect, with a decreasefrom 2,012 to 1,934 BU at ambient and controlled conditions of storage,respectively (Fig. 4B). According to various studies, the differences in thepeaks of iron-fortified flours might be a result of the differences in the


chemical nature of iron salts and fortification levels; too high of a curvemight correspond to a low level of amylase activity, and too low a curve resultsfrom excessive alpha amylase activity. The PV of WWF is affected by wheatvarieties and nature of fortificants (Pyler 1973; Siddique 1989).

It may be the chemical nature of the fortificant and the concentration ofiron in the compound that might have differently acted for this particularrheological activity. The findings of the present research contradicted withthose of Saldamli et al. (1996), who observed no effect of adding higher levelsof zinc on the rheological and baking properties of dough prepared from wheatflour. It is the iron in combination with zinc that might have a different effectduring this study as compared with the findings of Saldamli et al. (1996), whoused zinc alone in their study.

CONCLUSIONS

In order to make any fortification program a success, it is important thatthe physicochemical changes, taking place in the vehicle and the end product,as a result of fortification are to be carefully monitored. Addition of iron andzinc fortificants to WWF did not exhibit any critical alteration in the basiccomposition of the flours, and marginal differences in various flour attributesconcerning rheology were detected. Higher WA as a result of mineral fortifi-cation was observed in this study. DDT and DS of flours fortified with mineralsare not influenced negatively. However, the results indicated that NaFeEDTA

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T0 T1 T2 T3 T4Fortified flour

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)

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)

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)

A

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Storage conditions

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FIG. 4. EFFECT OF FORTIFICATION ON PEAK VISCOSITY (PV) OF DIFFERENTFORTIFIED WHOLE WHEAT FLOURS

(A) PV of fortified flours during storage, irrespective of treatment types, packaging materials andstorage conditions. (B) PV of fortified flours in different storage conditions (� ambient, 35–45C;� controlled 23–25C with relative humidity 45–55%) irrespective of treatment type, storage time

and packaging materials. (C) PV of different fortified flours irrespective of storage time,packaging materials and storage conditions.

T0, unfortified flour; T1, fortified with NaFeEDTA + zinc sulfate; T2, fortified withNaFeEDTA + zinc oxide; T3, elemental iron + zinc sulfate; T4, elemental iron + zinc oxide;

BU, Brabender unit.

62 S. AKHTAR ET AL.

had a smaller effect on the rheology of the flours compared with elemental ironand could be a choice for iron fortification of WWFs. Zinc fortificants do notappear to impart any significant change in dough rheological characteristics.Marginal changes in rheological quality of the flours may be compromisedwith greater health benefits of adding micronutrients to flour.

ACKNOWLEDGMENT

Authors thank the Higher Education Commission of Pakistan forproviding funds to conduct this research.

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EFFECT OF MINERAL FORTIFICATION ON RHEOLOGICAL PROPERTIES OF WHOLE WHEAT FLOUR