Original article

Bread and durum wheat compared for antioxidants contents, and

lipoxygenase and peroxidase activities

Sla �dana Zilic,1* Dejan Dodig,1 Vesna Hadzi-Taskovic Sukalovic,2 Milan Maksimovic,3 Goran Saratlic1 & Biljana

Skrbic4

1 Maize Research Institute, Zemun Polje, Slobodana Bajica 1, 11185 Belgrade, Serbia

2 Institute for Multidisciplinary Research, Kneza Viseslava 1, 11030 Belgrade, Serbia

3 Military Medical Academy, Institute of Hygiene, 11000 Belgrade, Serbia

4 Faculty of Technology, University of Novi Sad, Bul. cara Lazara 1, 21000 Novi Sad, Serbia

(Received 7 September 2009; Accepted in revised form 12 March 2010)

Summary Potential beneficial components, including proteins, total phenolics, total flavonoids, carotenoids, tocophe-

rols, and DPPH radical scavenging activity, were investigated in wholemeal of ten bread (T. aestivum L.) and

ten durum (T. durum Desf.) novel wheat genotypes. In addition, the activity rate of lipoxygenase (LOX) and

peroxidase (POD) enzymes implicated in the antioxidant metabolism was determined. The protein contnet

and the antioxidant properties varied according to the two different wheat species, as well as, between the

different bread and durum wheat genotypes themselves. The results indicated significant differences in

proteins and antioxidant compounds between bread and durum wheat. Higher total proteins, wet gluten and

antioxidants contents, combined with lower LOX and POD activities, point to a higher nutritive value of

durum wheat than bread wheat.

Keywords Antioxidants, bread wheat, durum wheat, lipoxygenase, peroxidase, radical scavenging activity.

Introduction

Wheat has traditionally been selected for functionality,for example, baking or biscuit values, while the nutri-tional value of the grain has been almost neglected.However, during the last 10 years much more attentionhas been paid to the phytonutrients of wheat aspotential antioxidants acting on the health benefits(Fardet et al., 2008).Antioxidant properties of wheat derive mainly from

phenolics and lipid-soluble compounds, carotenoids andtocopherols. The most common phenolic compoundsfound in whole grains are phenolic acids and flavonoidswith ferulic acid as the predominant phenolic acid(Moore et al., 2005). In whole wheat flour, Liu (2007)found that the bran ⁄germ fraction contributed 83% ofthe total phenolic content and 79% of the totalflavonoid content.Carotenoids are the most widespread pigments in

nature and their function is to protect plants fromphoto-induced free radical damage (Dammig-Adamset al., 1996). Their role in humans is supposed to besimilar (Krinsky, 2002). Generally, non-provitamin Aactivity, lutein, followed by its stereo isomer zeaxan-

thin is the major carotenoids of yellow-colouredkernels (Panfili et al., 2004; Moore et al., 2005). Theconcentration of carotenoids is low in bread wheat,while it is more abundant in durum wheat (Panfiliet al., 2004).Tocopherols and tocotrienols (tocols) are a group of

soluble lipid compounds recognised as a generic term forvitamin E. Tocopherol compounds are mostly present inthe germ fraction of wheat grain. They are abundant inboth, durum and bread wheat. The content of totaltocols in the whole grains of soft wheat is 75 mg kg)1

dry weight (Panfili et al., 2003) with 3.4–10.1 mg kg)1 ofa-tocopherol (Moore et al., 2005). In durum wheat, thecontent of a-tocopherol ranged from 2.08 to 3.11 lg g)1

(Borrelli et al., 2008).Wheat grain contains several oxidase enzymes, such as

lipoxygenase (LOX) and peroxidase (POD) that areimplicated in the antioxidant metabolism, and thereforecould influence changes in the antioxidant potential offinal products. The LOX action on its substrate-polyunsaturated fatty acid generates highly reactivecompounds that are initiators of a cascade reaction inwhich components playing no part in enzymatic reac-tions may be affected secondarily, resulting in indirectlosses of a nutritive value, alterations of organolepticproperties and the colour. For example, loss of the*Correspondent: E-mail: szilic@mrizp.rs

International Journal of Food Science and Technology 2010, 45, 1360–13671360

doi:10.1111/j.1365-2621.2010.02251.x

� 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology

colour observed during pasta processing is due to theLOX-linoleic acid system, which is responsible for anoxidative degradation of carotenoid pigments (Tronoet al., 1999). In vivo POD play a role in the cell wallformation, both during a regular plant growth (Schop-fer, 1996), and in a response to wounding and infections(Graham & Graham, 1991). In the processes of thepreparation of wheat-finished products for humanconsumption POD has an opposite role. Besides itsundesirable reaction in the oxidative degradation ofcarotenoid pigments (Gelinas et al., 1998; Borrelli et al.,2003) in bread making technology POD is a usefulenzyme to improve rheological properties of dough(Figueroa-Espinoza et al., 1999; Takasaki et al., 2005).The goals of this study are as follows: (i) to evaluate

the magnitude of potential beneficial components (totalphenolics, total flavonoids, tocopherols, carotenoids,DPPH• radical scavenging activities, lipoxygenase andperoxidase activity) across the kernel of ten bread andten durum wheat genotypes; (ii) to verify differencesbetween durum and bread wheat.

Materials and methods

Wheat samples

The experimental material consisted of ten bread (Trit-icum aestivum L.) and ten durum (Triticum durum Desf.)wheat genotypes recently developed at the MaizeResearch Institute Zemun Polje (MRIZP), Serbia. Thegenotypes were chosen on the basis of their differences inagronomic traits such as yield and its components. Theirnames, pedigrees, origin and growth type are given inTable 1. Grain samples of bread and durum wheat werecollected from plants grown in a field-trial at theMRIZP in 2008–2009 growing season. Standard agro-nomic practices were used to provide adequate nutritionand to keep the plots free of diseases. For the analysis ofboth wheat species, the wholemeal (particle size<500 lm) was obtained by grounding wheat grains ona Cyclotec 1093 lab mill (FOSS Tecator, Sweden).

Chemical analysis

For the DPPH test the wheat grain extract was preparedby continuous shaking 0.3 g of wholemeal in 10 mL of70% (v ⁄v) acetone for 30 min at room temperature.After centrifugation (20 min at 20 000 g) supernatantwas used for the detection of the DPPH• scavengingactivity according to the Abe et al. (1998) assay. Theresults were expressed as an IC50 value that representsthe amount of wholemeal (in mg d.w.) providing 50%inhibition of DPPH•.Total phenolics were determined from the same

extract as for the DPPH test by using the Folin-Ciocalteu procedure (Hagerman et al., 2000). The total

phenolic content was calculated as a catechin equivalent(CE) from the calibration curve of catechin standardsolutions and expressed in mg g)1d.w. Total flavonoidswere determined from the same extract as for the DPPHtest. Spectrophotometric measurements at 360 nm(e = 13.6 m m

)1 cm)1) were used to determine totalflavonoids in the same extract (Markham, 1993). Water-saturated 1-butanol was chosen for the yellow pigmentextraction. An approximately 8-g wheat sample washomogenised in 40 mL of solvent for 60 s, kept for20 min at room temperature, and homogenised againfor 30 s. The mixture was centrifuged at 13 000 g for10 min, and an aliquot of the supernatant was filteredthrough the Whatman No. 1 filter paper. The pigmentcontent of extract can be calculated directly fromabsorbance reading at 435.8 nm, using conversionfactor 1.6632 (AACC, 1995). The tocopherol content(lg g)1 d.w.) was determined by the HPLC method(Oufnac et al., 2007).The LOX (EC 1.13.11.12) activity was determined in

the crude wholemeal homogenate prepared by shakingthe sample with one volume of 0.2 m sodium phosphatebuffer (pH 7.5) at 4 �C for 120 min. The supernatantobtained by centrifugation at 20 000 g for 15 min, wasused to measure the LOX activity. The assay mixture

Table 1 Name, pedigree, origin and growth type of ZP bread and

durum genotypes

Genotypes Parents (Origin) Growth type

Bread wheat

ZP OP ⁄ 08-2 Evropa 90 (Serbia) · Studenica (Serbia) Winter

ZP OP ⁄ 08-3 Jasenica (Serbia) · Apache (France) Winter

ZP OP ⁄ 08-1 Vizija (Serbia) · Proteinka (Serbia) Winter

ZP 87 ⁄ I L-99 (Serbia) · Pobeda (Serbia) Facultative

ZP Oka Tanjugovka (Serbia) · Rodna (Serbia) Winter

ZP Zlatna Jasenica (Serbia) · Rodna (Serbia) Winter

ZP OP ⁄ 07-1 Skopljanka (Macedonia) · Proteinka

(Serbia)

Winter

ZP OP ⁄ 07-2 L-99 (Serbia) · Renesansa (Serbia) Facultative

ZP-OP ⁄ 07-3 Orovcanka (Macedonia) · Proteinka

(Serbia)

Winter

ZP Prva Jasenica (Serbia) · L-23 ⁄ 24 (Serbia) Winter

Durum wheat

ZP 33 ⁄ I SOD 55 (Slovakia) · Neodur (France) Winter

ZP OD ⁄ 07-1 L-48 (Serbia) · Waha (ICARDA) Facultative

ZP 10 ⁄ I Windur (Germany) · Rodur (Romania) Winter

ZP OD ⁄ 07-3 Varano (Italy) · Gidara-2 (ICARDA) Facultative

ZP 34 ⁄ I SOD 55 (Slovakia) · Korifla (ICARDA) Facultative

ZP OD ⁄ 07-2 L-48 (Serbia) · Om Rabi 5 (ICARDA) Facultative

ZP OD ⁄ 08-1 Mina (Macedonia) · Betadur (Hungary) Winter

ZP OD ⁄ 08-2 Mina (Macedonia) · Gidara-2 (ICARDA) Facultative

ZP OD ⁄ 08-3 Varano (Italy) · Lagaramb-1 (ICARDA) Facultative

ZP 120 ⁄ I Windur (Germany) · Kavadarka

(Macedonia)

Winter

ICARDA = International Center for Agricultural Research in the Dry

Areas.

Bread and durum wheat compared for antioxidants contents, and lipoxygenase and peroxidase activities S. Zilic et al. 1361

� 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology International Journal of Food Science and Technology 2010

consisted of 50 mm linoleic acid in 0.2 m sodiumphosphate buffer, pH 6.5, and an aliquot of the sample.The initial rate of the absorbance changes at 234 nm(e = 2.5 · 104 m

)1 cm)1) was recorded. The LOXactivity was expressed in lmol of conjugated dieneformed per minute and g d.w. (Axelrod et al., 1981;Leenhardt et al., 2006a).To determine the POD (EC 1.11.1.7) activity, whole-

meal (0.5 g) was extracted in 10 mL of 0.1 m K-phosphate buffer, pH 7.6 at 4 �C with constant stirringfor 1 h. After centrifugation at 20 000 g for 15 min theobtained supernatant was used in the POD assaywith ferulic acid as a hydrogen donor. The initialrate of the absorbance changes at 286 nm(e = 1.68 · 104 m

)1 cm)1) was used for the calculationof the POD activity (Hadzi-Taskovic Sukalovic et al.,2003).The wet gluten (%) was obtained by rinsing 10 g of

wheat dough with a 2% sodium chloride solution,followed by water rinsing, mechanical folding, pressing,and stretching in order to release soluble ingredients andstarch. The standard chemical method (Official Gazetteof SFRY, 1987) was applied to determine the content oftotal proteins (expressed in % of dry weight).

Statistical analysis

All chemical analyses were performed in three replicatesand the results were statistically analysed. Significantdifferences between genotype means were determined bythe Fisher’s least significant differences (LSD) test, afterthe analysis of variance (anova) for trials set upaccording to the RCB design. A t-test was performedto test the significance of differences between the speciesmeans. Differences with P < 0.05 were consideredsignificant in both tests. The coefficient of variation(CV) was determined for each trait.

Results

In order to assess the nutritional value of the investi-gated wheat genotypes wholemeal was used as a sourceof protective micronutrients. The content of totalproteins and wet gluten of bread and durum wheatwholemeal are shown in Table 2.Durum wheat contained significantly higher amounts

of total proteins and wet gluten than bread wheat. Thecontent of total proteins ranged from 10.87 to 13.04%and 11.46% to 16.53% in bread and durum genotypes,respectively. Wet gluten ranged from 17.65% to 28.15%and 23.35% to 48.85% in bread and durum genotypes,respectively. Considerable variation for wet gluten(CV = 13.25%) among genotypes of bread wheat, aswell as, for total proteins (CV = 10.90%) and wetgluten (CV = 19.57%) among durum wheat genotypeswere found.

The values of the yellow pigment content for bothspecies did not overlap and ranged from 2.02 to3.95 lg g)1 d.w. and from 3.98 to 5.91 lg g)1 d.w. inbread and durum wheat, respectively (Table 3). Durumwheat contained about 56% as much the yellow pigmentas the bread wheat. Considerable variation existedamong bread (CV = 21.15%) and durum wheat(13.53%) genotypes for the yellow pigment content.The DPPH• scavenging activity of wholemeal is shown

in Table 3. The wholemeal from durum wheat had asignificantly lower IC50 value than bread wheat and,therefore, durum wheat showed a stronger DPPH•

scavenging activity than bread wheat. The IC50 valuesranged from 11.83 to 13.66 mg d.w. and 10.08 to13.41 mg d.w. in bread and durum genotypes, respec-tively. To compare two wheat species under our exper-imental conditions, 8.8 lg of ascorbic acid were able toscavenge 50% of DPPH•. The total phenolic content,expressed in CE (mg g)1 d.w.), was significantly higherin durum than bread wheat (Table 3). The average value

Table 2 Total proteins and wet gluten content in bread and durum

wheat grains

Genotypes

Total proteins

(% d.w.)

Wet gluten

(% d.w.)

Bread wheat

ZP OP ⁄ 08-2 11.33cd 21.20e

ZP OP ⁄ 08-3 11.32cd 17.65f

ZP OP ⁄ 08-1 11.25d 20.31e

ZP 87 ⁄ I 12.09bc 21.12e

ZP Oka 11.62bcd 26.30b

ZP Zlatna 13.04a 28.15a

ZP OP ⁄ 07-1 12.04bc 24.43cd

ZP OP ⁄ 07-2 12.32ab 26.15b

ZP-OP ⁄ 07-3 10.87d 23.15d

ZP Prva 11.40cd 25.20bc

F test *** ***

CV (%) 5.29 13.25

Durum wheat

ZP 33 ⁄ I 14.47b 37.10d

ZP OD ⁄ 07-1 12.78d 44.00b

ZP 10 ⁄ I 11.46e 23.35h

ZP OD ⁄ 07-3 13.79bc 30.45g

ZP 34 ⁄ I 13.03cd 33.55ef

ZP OD ⁄ 07-2 16.53a 48.85a

ZP OD ⁄ 08-1 13.50cd 33.90e

ZP OD ⁄ 08-2 14.59b 39.10cd

ZP OD ⁄ 08-3 16.00a 39.48c

ZP 120 ⁄ I 12.75d 31.50fg

F test *** ***

CV (%) 10.90 19.57

Mean (bread wheat) 11.72b 23.37b

Mean (durum wheat) 13.89a 36.13a

Mean of genotype and species followed by the same letter within same

column are not significantly different (P < 0.05).

***Significant at P < 0.001.

CV, coefficient of variation

Bread and durum wheat compared for antioxidants contents, and lipoxygenase and peroxidase activities S. Zilic et al.1362

International Journal of Food Science and Technology 2010 � 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology

of the total phenolic content was 1.11 (ranged from 1.02to 1.27) and 1.36 mg g)1 d.w. (ranged from 1.21 to 1.59)in bread and durum wheat, respectively. The totalflavonoids content was also significantly higher in durum(0.930 mg g)1 d.w.) than in bread wheat(0.701 mg g)1d.w.). It ranged from 0.644 to0.759 lg g)1 d.w. and 0.703 to 1.185 lg g)1 d.w. inbread and durum wheat, respectively (Table 3). Coeffi-cients of variation for DPPH• scavenging activities andthe total phenolic content were similar but relatively lowfor both species. However, considerable higher variationfor total flavonoids was found in durum (16.26%) thanin bread (6.37%) wheat (Table 3).Each bread and durum genotype was examined for

a- and b+c-tocopherol contents (Table 4). The resultsshowed that all tested bread and durum wheat geno-

types contained a-tocopherol, with a range of 4.34–9.15 lg g)1 d.w. and 4.72–10.16 lg g)1 d.w., respec-tively, and the average content of a-tocopherol inbread (6.51) and durum wheat (7.91) not differedsignificantly. The content of b+c-tocopherol was muchlower than a-tocopherol in both wheat species. Coef-ficients of variation for all tocopherols among breadand durum wheat genotypes were similar and ratherhigh (over 25%).The LOX activity significantly differed between the

two species, with an activity level of durum wheat lowerby 30.02% (0.65 lmol g)1 d.w. min)1) than bread wheat(0.93 lmol g)1 d.w. min)1) (Table 5). The POD activity,calculated as lmoles of ferulic acid oxidised per g d.w.min)1, was also significantly lower (21.2%) in durum(6.06) than in bread wheat (7.69). High variation for theLOX and POX activity was observed among bread anddurum wheat genotypes.Generally, for all traits there were significant differ-

ences among bread and durum wheat genotypes used inthis study.

Table 3 Antioxidants content in bread and durum wheat grains

Genotypes

Yellow

pigment

(lg g)1d.w.)

Total

phenolics

(CE, mg g)1

d.w.)

Total

flavonoids

(lg g)1 d.w.)

DPPH•

scavenging

(IC50) (mg)

Bread wheat

ZP OP ⁄ 08-2 3.95a 1.19a 0.759a 12.39bc

ZP OP ⁄ 08-3 3.34ab 1.13a 0.731a 12.48bc

ZP OP ⁄ 08-1 3.15b 1.07a 0.680a 12.89ab

ZP 87 ⁄ I 3.40b 1.02a 0.644a 13.41a

ZP Oka 3.06b 1.14a 0.655a 13.66a

ZP Zlatna 3.21b 1.03a 0.717a 13.65a

ZP OP ⁄ 07-1 3.03b 1.27a 0.746a 11.83c

ZP OP ⁄ 07-2 2.29c 1.17a 0.740a 11.84c

ZP-OP ⁄ 07-3 2.02c 1.06a 0.647a 12.95ab

ZP Prva 2.08c 1.02a 0.685a 12.00bc

F test *** n.s. n.s. ***

CV (%) 21.15 7.95 6.37 5.66

Durum wheat

ZP 33 ⁄ I 4.24cd 1.21a 0.940ab 12.38ab

ZP OD ⁄ 07-1 5.17b 1.26a 0.758b 13.41a

ZP 10 ⁄ I 4.25cd 1.25a 0.773b 12.61ab

ZP OD ⁄ 07-3 4.87bc 1.40a 1.090a 12.12bc

ZP 34 ⁄ I 3.98d 1.59a 1.185a 10.83cd

ZP OD ⁄ 07-2 5.91a 1.46a 1.045a 10.08d

ZP OD ⁄ 08-1 4.92bc 1.32a 0.947ab 11.66bc

ZP OD ⁄ 08-2 4.07d 1.24a 0.703b 12.38ab

ZP OD ⁄ 08-3 4.84bc 1.50a 0.982ab 10.51d

ZP 120 ⁄ I 3.98d 1.34a 0.878b 11.41cd

F test *** n.s. *** ***

CV (%) 13.53 9.29 16.26 8.87

Mean

(bread wheat)

2.96b 1.11b 0.701b 12.71a

Mean

(durum wheat)

4.62a 1.36a 0.930a 11.74b

Mean of genotype and species followed by the same letter within same

column are not significantly different (P < 0.05).

*** and n.s. = significant at P < 0.001 and not significant.

CV, coefficient of variation

Table 4 Tocopherol content in bread and durum wheat grains

Genotypes

a tocopherol

(lg g)1d.w.)

b+c tocopherol

(lg g)1 d.w.)

Total tocopherol

(lg g)1 d.w.)

Bread wheat

ZP OP ⁄ 08-2 5.04d 2.05c 7.09d

ZP OP ⁄ 08-3 7.60b 2.72b 10.32b

ZP OP ⁄ 08-1 6.10c 2.77ab 8.87c

ZP 87 ⁄ I 4.57de 1.84d 6.41de

ZP Oka 7.99b 2.60bc 10.59b

ZP Zlatna 6.58c 2.41bc 9.00c

ZP OP ⁄ 07-1 8.99a 2.95ab 11.94a

ZP OP ⁄ 07-2 9.15a 3.40a 12.56a

ZP-OP ⁄ 07-3 4.34de 1.67cd 6.02e

ZP Prva 4.73de 1.20d 5.93e

F test *** *** ***

CV (%) 27.58 27.94 27.00

Durum wheat

ZP 33 ⁄ I 6.19d 1.98c 8.18de

ZP OD ⁄ 07-1 4.72de 1.19d 5.91f

ZP 10 ⁄ I 7.55c 2.76ab 10.31bc

ZP OD ⁄ 07-3 7.05c 2.37bc 9.42cd

ZP 34 ⁄ I 9.99a 3.12a 13.11a

ZP OD ⁄ 07-2 10.16a 3.29a 13.45a

ZP OD ⁄ 08-1 5.25de 2.00c 7.25e

ZP OD ⁄ 08-2 9.52a 2.97ab 12.49a

ZP OD ⁄ 08-3 9.99a 2.99ab 12.98a

ZP 120 ⁄ I 8.66b 2.68ab 11.34b

F test *** *** ***

CV (%) 25.40 25.41 25.08

Mean (bread wheat) 6.51a 2.36a 8.87a

Mean (durum wheat) 7.91a 2.53a 10.45a

Mean of genotype and species followed by the same letter within same

column are not significantly different (P < 0.05).

***Significant at P < 0.001.

CV, coefficient of variation

Bread and durum wheat compared for antioxidants contents, and lipoxygenase and peroxidase activities S. Zilic et al. 1363

� 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology International Journal of Food Science and Technology 2010

Discussion

Our results provided the evidence of differences in levelsof proteins, antioxidants and oxidases between andwithin two wheat species. There was a wide variationamongst germplasm for the majority of analysedparameters.Wheat grain contains a wide array of phytochemicals

that include a range of phenolic compounds, carote-noids and tocopherol, which according to the ‘anti-oxidant hypothesis’ afford protection against chronicdiseases by decreasing oxidative damage (Meydani,2002). Different concentrations of these compoundswere found in the anatomic parts of the grain. Phenolicsare highly concentrated in bran layers (Li et al., 2005),carotenoids in outer layers of the kernel, opposite totocopherol, found mostly in the germ. Therefore, thewhole grain products could be considered as foodproducts with maximum health benefits.

The yellow pigment content, phenolics and tocophe-rols, was more abundant in ZP durum than ZP breadwheat genotypes, although not significantly in the caseof tocopherols. All these nutrients with antioxidantproperties influenced the capacity of DPPH• scavenging.Accordingly, durum wholemeal had a higher DPPH•

scavenging activity, and a higher nutritive value. Amongthe investigated antioxidants (Table 3), the greatestcoefficient of variation in both species was detected inthe yellow pigment content. In the present study, it wasshown that the yellow pigment concentration of breadand durum wheat genotypes, adapted to south-eastEuropean conditions, ranged from 2.02 to 3.95 mg kg)1

and 3.98 to 5.91 mg kg)1, respectively. Our results werein agreement with results obtained by Adom & Liu(2003) who found a higher carotenoid content in durumthan bread wheat. Although a relatively small sample ofgenotypes was used in this study, we found yellowpigment values that were without doubt higher to thatreported by Panfili et al. (2004) for bread (0.1–2.4 mg kg)1) and durum wheat (1.5–4.0 mg kg)1). Theyellow endosperm is a particularly desirable trait fordurum wheat, because it gives the pasta its goldencolour. Colour is one of the main factors affectingdurum end-use products and the consumer’s choice.Consequently, in durum wheat breeding programmes,this trait is considered as one of the main criteria forassessing the commercial and nutritional value of pastaproducts and large genotypic differences in the caroten-oid content may open up new opportunities for breed-ing wheat varieties with a higher nutritional value(Adom & Liu, 2003). The yellow pigment range (3.98–5.91 mg kg)1) obtained for ZP durum genotypes grownin Serbia were higher than that of 1.82 to 4.59 lg g)1

reported by Borrelli et al. (2008) for six durum cultivarsgrown in Italy, although variability was lower (1.93%vs. 2.77%). Nevertheless, Abdel-Aal et al. (2007) re-ported for cultivar Kyle, grown in Canada, the amountof the yellow pigment of 6.27 lg g)1. It seems that thereis still opportunity for improving the yellow pigmentcontent in new ZP durum wheat lines and cultivars.Unlike for durum wheat, the high pigment concen-

tration in bread wheat has not been considered animportant trait in breeding and selection and onlyrecently the demand in the bread trade has risen(Leenhardt et al., 2006). Seven out of ten ZP breadwheat genotypes had the yellow pigment content higherthan 3.0 mg kg)1, with a maximum value of 3.95. Thesevalues are generally higher than those found in literaturefor bread wheat (Panfili et al., 2004; Abdel-Aal et al.,2007). Furthermore, Leenhardt et al. (2006b) reportedthat the carotenoid concentration of forty-eight breadwheat cultivars adapted to north-western Europeanconditions ranged from 0.43 to 1.74 lg g)1.Phenolic compounds in wholemeal deserve much

more attention because the total phenolic content

Table 5 Lipoxygenase and peroxidase activity in bread and durum

wheat grains

Genotypes

LOX activity

(lmol g)1 d.w. min)1)

POD activity

(lmol ferulic

acid g)1 d.w. min)1)

Bread wheat

ZP OP ⁄ 08-2 0.90cd 7.68d

ZP OP ⁄ 08-3 1.35a 7.16d

ZP OP ⁄ 08-1 0.82cd 7.05d

ZP 87 ⁄ I 1.04bc 8.53c

ZP Oka 1.18ab 5.44e

ZP Zlatna 0.67d 5.50e

ZP OP ⁄ 07-1 0.83cd 9.42b

ZP OP ⁄ 07-2 0.80cd 11.16a

ZP-OP ⁄ 07-3 0.93bc 7.31d

ZP Prva 0.84cd 7.62d

F test *** ***

CV (%) 22.26 21.76

Durum wheat

ZP 33 ⁄ I 0.85a 7.60a

ZP OD ⁄ 07-1 0.56b 4.61e

ZP 10 ⁄ I 0.97a 4.91e

ZP OD ⁄ 07-3 0.83a 6.74bc

ZP 34 ⁄ I 0.36c 6.44cd

ZP OD ⁄ 07-2 0.49bc 7.35ab

ZP OD ⁄ 08-1 0.46bc 5.98d

ZP OD ⁄ 08-2 0.87a 6.78bc

ZP OD ⁄ 08-3 0.55b 5.10e

ZP 120 ⁄ I 0.63b 5.09e

F test *** ***

CV (%) 31.33 17.45

Mean (bread wheat) 0.93a 7.69a

Mean (durum wheat) 0.65b 6.06b

Mean of genotype and species followed by the same letter within same

column are not significantly different (P < 0.05).

***Significant at P < 0.001.

CV, coefficient of variationPOD activity lmol ferulic acid g)1 d.w. min)1

Bread and durum wheat compared for antioxidants contents, and lipoxygenase and peroxidase activities S. Zilic et al.1364

International Journal of Food Science and Technology 2010 � 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology

strongly correlates with the total antioxidant activity(Verma et al., 2008). The same relation was obtained inthe investigated ZP bread and durum wheat genotypes.Although statistically significant differences in totalphenolic content and the DPPH• scavenging activitywere obtained among the tested ZP genotypes, theranges in mean values did not vary greatly. Neverthe-less, significant differences in the scavenging activitiesand the total phenolic content between bread anddurum wheat were found. The range obtained for ZPbread wheat genotypes (1.02 to 1.27 mg catechin g)1

d.w.) was higher than that reported by Adom et al.(2003) for eleven wheat varieties (0.710 to 0.858 mg g)1,calculated as eq. of chatechin), but was lower by 20%than that of 1.23–1.64 mg g)1 d.w. (calculated as eq. ofcatechin) found for bread wheat grown in Italy (Irmaket al., 2008). Interestingly, mean total phenolic contentof ten ZP durum wheat genotypes (1.36 mg catechin g)1

d.w.) was rather higher than that of ten durum wheatcultivars (0.871 mg g)1 d.w., calculated as eq. ofcatechin), also grown in Italy (Dinelli et al., 2009).Ferulic acid, as the most effective antioxidant comparedto other wheat free phenolic acids (Baublis et al., 2000),was designated as the predominant phenolic acid espe-cially in durum wheat cultivars. Due to its semi-elasticproperties, this compound has an ability to formcomplexes with pentosanes and proteins and is impor-tant in the formation of the dough texture (Klepacka &Fornal, 2006). It was observed that differences in theferulic acid content among durum wheat cultivarscorresponded to levels of enzymes involved in thephenolic acid metabolism (Regnier & Macheix, 1996).Flavonoids are another important class of phyto-

chemicals in wheat contributing to its health beneficialproperties (Willcox et al., 2004). Known properties ofthe flavonoids include free radical scavenging, strongantioxidant activity, inhibition of hydrolytic and oxida-tive enzymes (phospholipase A2, cyclooxygenase, lipox-ygenase), and anti-inflammatory action (Zhishen et al.,1999). The results showed that mean values of the totalflavonoid content in bread wheat genotypes(0.701 mg g)1 d.w.) differed significantly from thosedetected in durum wheat (0.930 mg g)1 d.w.). As wasthe case for total phenolic content, mean total flavonoidcontent did not vary much among bread wheat geno-types (6.37%), but considerable variation was foundamong durum wheat genotypes (16.26%).Among the tocopherol isomers, a-tochoperhol

showed the highest vitamin E activity and reactivityagainst singlet oxygen (Zhou et al., 2004). Concentra-tions of a-tochopherol varied highly among bread(CV = 27.58%) and durum wheat genotypes (CV =25.40%). Concentrations in bread wheat ranged from4.34 to 9.15 lg g)1 d.w. This range was lower to therange of 3.36–10.09 lg g)1 reported for bread wheat byMoore et al. (2005). Panfili et al. (2003) reported that

bread wheat contained almost as twice as mucha-tochopherol than durum wheat (15.9 and 8.4 lg g)1

for bread and durum wheat, respectively). In our study,the a-tochopherol concentration in durum wheat washigher than in bread wheat, although not significantly(7.91 and 6.51 lg g)1 for durum and bread wheat,respectively). The similar results were gained for b+c-tocopherol (2.53 and 2.36 lg g)1 for durum and breadwheat, respectively). According to the literature, it seemsthat ZP genotypes of both wheat species containedmoderate levels of tocopherols.Wheat is mainly consumed in a form of bread and

pasta products. It is therefore important to ensure thatthe antioxidant potential at the kernel level is main-tained in the final products. Oxidative enzymes, such asLOX and POD, are highly concentrated in the branlayer of the seeds (Rani et al., 2001) and during storageor processing of wheat dough, they could be responsiblefor the decline of the initial level of antioxidants. Bothenzymes can be responsible for the carotenoid oxidativedegradation during dough-making and bread-makingespecially when wholemeal was used (Delcros et al.,1998; Trono et al., 1999). LOX levels in durum arecultivar-related and depend on the environmental con-ditions (Borrelli et al., 1999). Our results highlightedremarkable differences in LOX and POD activity amonggenotypes of both wheat species, confirming the geno-typic nature of this character. In agreement with thedata of Leenhardt et al. (2006), our results showed indurum wheat a lower activities of LOX and PODenzymes than in bread wheat, and a negative and highlysignificant correlation between the LOX and PODactivity and the carotenoid concentration (r2 = 0.50and 0.48, respectively, P < 0.05, d.f. = 19). Conse-quently, Leenhardt et al. (2006b) suggested that in aperspective of bread-making the ratio between the totalcarotenoid concentration and the LOX activity wouldbe a suitable criterion for wheat breeding programmes.In addition to lower enzymatic activity, the highercontent of tocopherols and yellow pigments in durumwheat could be helpful in prevention of the pigment lossduring pasta processing, because of the fact that theb-carotene and a-tocopherol are able to inhibit LOXfrom various systems (Pastore et al., 1999). Neverthe-less, the activities of LOX and POD are desirable inbread making because they promote the fermentationresulting in the bread texture improvement. The linoleicacid oxidised by LOX interacts with gluten givingcrosslinked gluten that influences the expansion duringdough fermentation (Toyosaki, 2007). Gluten proteinsare primarily responsible for the end-use wheat quality.Besides, few studies confirmed antioxidative peptidesfrom wheat gluten (Wang et al., 2007; Kong et al.,2008). The wet gluten content obtained in ZP breadwheat genotypes (17.65–28.15%) can not be regardedfavourable, as it was rather lower compared to that

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� 2010 The Authors. Journal compilation � 2010 Institute of Food Science and Technology International Journal of Food Science and Technology 2010

reported by Simic et al. (2006) for ten bread wheatcultivars grown in nearby Croatia (29.20 to 47.90%). Onthe other hand, wet gluten content in ZP durum wheatgenotypes (36.13%) was higher than in thirteen durumcultivars grown in Czech Republic (Stehno, 2009).

Conclusions

The obtained data highlighted differences in theconcentration of antioxidative compounds, as well as,the constitutive activity of oxidative enzymes betweendurum and bread genotypes considered in this study.Significant genotype variation of wet gluten, yellowpigment, tocopherols and LOX and POD activity couldbe used to increase the nutritional value of bread anddurum wheat products. Comparing with data found inliterature, it obvious that there is still opportunity forimproving nutrient properties in new ZP bread anddurum wheat lines and cultivars.

Acknowledgments

This work was supported by the Ministry of Science andTechnological Development of the Republic Serbia(grants no. 20017, 143020B, and 152001B).

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