Bioactive healthy components of bulgur

Abstract

Bulgur has been one of the most important traditional Durum wheat products in Turkey and Middle Eastern countries for ages. The objective of this study was to reveal the composition of some healthy components of industrial bulgur samples produced in Turkey. Total starch, resistant starch, dietary fibre and total phenolic contents and their high-performance liquid chromatography (HPLC) profile and antioxidant capacity of bulgur samples using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activity methods were investigated. The results showed that total dietary fibre ranged between 5.8 ± 0.7 and 8.2 ± 0.7% and resistant starch between 2.1 ± 0.2 and 2.8 ± 0.2%. Moreover, phenolic content with an average of 59.5 ± 5.2 mg Gallic acid/100 g dry matter and a moderate level of antioxidant capacity with an average of 22.2 ± 2.4% DPPH scavenging activity and 563.3 ± 60.7 μmol Trolox Equivalent Antioxidant Capacity/100 g dry matter of ABTS scavenging activity add value to the health benefits of bulgur product.

Full text

Bioactive healthy components of bulgur
ZEYNEP TACER CABA
1
, M. HIKMET BOYACIOGLU
2
, & DILEK BOYACIOGLU
1
1
Food Engineering Department, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Maslak,
Istanbul, Turkey, and
2
Doruk Group, Cereal Foods Institute, Istanbul, Turkey
Abstract
Bulgur has been one of the most important traditional Durum wheat products in Turkey and Middle Eastern countries for
ages. The objective of this study was to reveal the composition of some healthy components of industrial bulgur samples
produced in Turkey. Total starch, resistant starch, dietary fibre and total phenolic contents and their high-performance
liquid chromatography (HPLC) profile and antioxidant capacity of bulgur samples using 2,2-diphenyl-1-picrylhydrazyl
(DPPH) and 2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activity methods were
investigated. The results showed that total dietary fibre ranged between 5.8 ^0.7 and 8.2 ^0.7% and resistant starch
between 2.1 ^0.2 and 2.8 ^0.2%. Moreover, phenolic content with an average of 59.5 ^5.2 mg Gallic acid/100 g
dry matter and a moderate level of antioxidant capacity with an average of 22.2 ^2.4% DPPH scavenging activity and
563.3 ^60.7 mmol Trolox Equivalent Antioxidant Capacity/100 g dry matter of ABTS scavenging activity add value to the
health benefits of bulgur product.
Keywords: functional properties, phenolics, resistant starch, antioxidant capacity
Abbreviations: HPLC: High-performance liquid chromatography, ABTS: 2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic
acid, DPPH: 2,2-diphenyl 1-picrylhydrazyl, TEAC: Trolox Equivalent Antioxidant Capacity
Introduction
Bulgur is a unique and appealing whole wheat product
that is mostly produced from Triticum durum variety.
It has contributed to Turkish and Middle Eastern
cuisine for ages with hundreds of traditional recipes
that offer both main and side dish alternatives (Quaglia
1988; Bayram and O
¨ner 2004). Bulgur is widely
accepted as a healthy commodity due to its nutrients
such as B vitamins, dietary fibre, minerals, unsaturated
fatty acids and folate (Kent and Evers 1994; Bayram
2007). Moreover, high amounts of minerals (phos-
phorus, zinc, magnesium and selenium) and cellulose
fibre in bulgur have been related to the protection
against constipation and colon cancer (Nouri 1988;
Ranum 1996). The product is a rapid-cooking, a ready
or semi-ready-to-eat, rice-like product as such
processes induce gelatinization of starch component
(Bayram 2000). Current bulgur production in Turkey
is estimated to be approximately 1 million tons
annually and its annual consumption reaches to
about 15 kg per person (Anon. 2006, 2009). Such a
high demand for bulgur clearly presents the signi-
ficance of this product in traditional Turkish diet.
In general, bulgur is commercially manufactured by
cooking wheat kernels in water, which is followed by
a drying step either under sunlight or in high drying
towers. These dried grains are partially dehulled and
ground to various particle sizes (Kadakal et al. 2007).
There are two different commercial techniques for
bulgur manufacturing in Turkey: ‘Gaziantep’ or
‘Karaman’ methods (indicating the name of cities
where most of the bulgur producers are located). In
the ‘Gaziantep’ manufacturing technique, processing
ISSN 0963-7486 print/ISSN 1465-3478 online q2011 Informa UK, Ltd.
DOI: 10.3109/09637486.2011.639748
Correspondence: Zeynep Tacer Caba, Food Engineering Department, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical
University, Maslak, 34469 Istanbul, Turkey. Tel: þ90 212 285 7207. Fax: þ90 212 285 7333. E-mail: tacerz@itu.edu.tr
International Jour nal of Food Sciences and Nutrition,
March 2012; 63(2): 250–256
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steps are in the order of cleaning, cooking, drying,
de-branning, cracking and milling (Babadog˘an 2010).
Although the first processing steps of cleaning and
cooking are similar in both methods, the major
difference in the ‘Karaman’ technique involve temper-
ing of cooked and subsequently dried wheat, which is
followed by de-branning, re-drying and milling steps
(Tu
¨rksoy and O
¨zkaya 2009).
Although the current literature about bulgur
primarily focuses on processing and the effects of
various parameters on product quality (Turhan et al.
2003; Bayram et al. 2004; Bayram 2005; Mohapatra
and Rao 2005), the information about other bioactive
components of bulgur other than dietary fibre,
minerals and vitamins in addition to its health effect
on glycaemic index and satiety (Jenkins et al. 1985;
O
¨zboy and Ko¨ksel 2001; Kadakal et al. 2007; Solah
et al. 2007) is limited. The objective of this study is to
add value to the potential functional properties of
bulgur by investigating some selected bioactive
components such as dietary fibre, resistant starch,
total phenolic constituents and antioxidant capacity.
Methods
Bulgur samples
A total of 15 commercial bulgur samples representing
5 trademarks (3 samples from each of the trademarks)
were obtained from different retailers in Turkey.
Particular attention was given to randomize samples
of each brand with different production dates
representing one single year of production.
Apparatus
UV– Visible spectrophotometer (Shimadzu UV-1700
Pharmaspec) was used for the determination of total
amount of phenolics and antioxidant activity. High-
performance liquid chromatography (HPLC) system
was equipped with a Waters 2695 Separation module,
a Waters 2996 PDA detector and a Supelcosil column
C18 (5 mm, 25 £4.6 mm). Empower Build 1154
software was used. A Hettich Centrifuge (Universal
32 R) was used for extractions.
Reagents
Protease (EC 3.4.21.14), a-amylase (EC 3.2.1.1),
amyloglucosidase (EC 3.2.1.3) enzymes were pur-
chased from Sigma Chemical Co. (St. Louis, MO,
USA). Folin–Ciocalteu reagent was acquired from
Merck KGaA (Darmstadt, Germany). 2,20-azino-
bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)
and 2,2 diphenyl 1-picrylhydrazyl (DPPH) were
purchased from Sigma Chemical Co. Gallic acid was
purchased from Sigma-Aldrich Co. (St. Louis, MO,
USA), trans-ferulic acid was purchased from Aldrich
w
Chemistry (St. Louis, MO, USA) and 4-hydroxy
benzoic acid standard was purchased from Merck
KGaA. HPLC-Grade acetic acid, methanol, aceto-
nitrile and water were obtained from Merck KGaA.
Preparation of bulgur samples for analyses
Bulgur samples were ground to 212 mm particle size
with a commercial coffee grinder (Depa Electronics,
Istanbul, Turkey). Two hundred grams of ground
bulgur samples were portioned in tightly capped and
stretch-film wrapped glass jars and stored in a cool
room until the analyses.
Proximate analysis
Moisture, ash and protein in the samples were
determined by AOAC methods 925.10, 923.03 and
920.87, respectively (Association of Official Analytical
Chemists 2002).
Starch, resistant starch and dietary fibre analyses
Total starch and total resistant starch of bulgur samples
were measured by the official methods 2002.02 and
32– 40 of AACC using the Resistant Starch Assay Kit
(Megazyme Int. Ireland Ltd, Wicklow, Ireland). The
dietary fibre content of the samples was determined
using Total Dietary Fiber Assay Kit (Sigma-Aldrich
Co.) based on the AOAC Method 985.29 (Association
of Official Analytical Chemists 1997).
Extraction of samples for analyses of total phenolics,
antioxidant activity and composition of phenolic
compounds by HPLC
According to the extraction procedure (Veliog˘lu et al.
1998) phenolic compounds were extracted with 2 ml
of 80% methanol containing 1% HCl using 200 mg
bulgur sample. The extraction solvent and the ground
sample were mixed in an orbital shaker at 200 rpm
for 2 h at ambient temperature. The mixture was then
centrifuged at 1250gfor 15 min. The aqueous phase
was separated and collected in another tube. The
extraction procedure was repeated on the precipitate.
Combined extracts were used for further analyses.
Total phenolic compounds
Total amount of phenolic compounds in bulgur
samples was determined by the modification of the
Folin– Ciocalteu method, using Gallic acid as a
standard (Singleton and Rossi 1965). Water (0.5 ml),
125 ml of sample extract and 125 mlofFolin–
Ciocalteu reagent (diluted with water, 1:10) were
added in a test tube. After standing for 6 min, 1.25 ml
of sodium carbonate solution (7.5%) and another
1 ml of water were added into the mixture solution.
The solution was left in the dark for 1.5 h. Absorbance
Bioactive healthy components of bulgur 251
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was measured at 760 nm in a spectrophotometer
(Singleton et al. 1999; Dewanto et al. 2002).
Phenolic composition by HPLC
The composition of phenolic compounds of the
samples was determined by a HPLC method
(Dragovic-Uzelac et al. 2005). Sample extracts were
first dissolved in methanol – water (50:50, v/v) solution
at a ratio of 1:1, filtered with a 0.45 mm nylon micro
filter (Phenomenex) and immediately injected into
HPLC. Two mobile phases composed of acetic acid –
water (3:97, v/v; phase A) and acetic acid – aceto-
nitrile – water (3:25:72, v/v; phase B) mixtures. In the
gradient system, phase A started at 100% level and
decreased to 30% with a flow rate of 1.0 ml/min. at the
end of 40 min. and then further to 20% level after
5 min and to 10% level at the end of 55min. with a
flow rate of 1.2 ml/min. That solvent ratio was kept till
the end of run (75 min.) Injection volume was 20 ml.
Total antioxidant activity
Total antioxidant capacity of bulgur samples was first
measured using DPPH radical scavenging activity %
method. According to the modified DPPH (1,1-
diphenyl-2-picrylhydrazyl) method (Ragaee et al.
2006), 1 ml of sample extract was added into a test
tube containing 4 ml of methanol (80%) and 1 ml
(containing 1 mmol DPPH) of freshly prepared DPPH
solution, and the final concentration of DPPH
solution was adjusted to 167 mmol. Then tubes were
left in the dark for 30 min and sample absorbance was
measured with a spectrophotometer at 517 nm.
Results were given for as ‘DPPH Scavenging Activity
%’. In addition, ABTS method (Miller and Rice-
Evans 1997) was used as the second method for the
determination of total antioxidant activity. ABTS
stock solution was diluted in 50 mM di-potassium
phosphate buffer (pH 8.0). One mililitre of that
solution was mixed with 100 ml of sample extract or
blank solution. After waiting for exactly 40 s, the
absorbance of the solution was determined with UV–
Visible spectrophotometer at 734 nm. Trolox was used
as a standard, and results were given as antioxidant
capacity for mmol of Trolox Equivalent Antioxidant
Capacity (TEAC) in 100 g dry matter (Miller and
Rice-Evans 1997). Analyses were carried out in
triplicates by both methods.
Statistical analysis
Statistical differences in the levels of bioactive
components of bulgur samples representing different
brands were analysed by one-way ANOVA using the
SPSS 16.0 statistical software (SPSS, Inc., Chicago,
IL, USA). The significant differences in mean values
were investigated by Duncan’s new multiple range test
at p,0.05 (Montgomery and Runger 2007). Pearson
correlation coefficients were calculated between
individual components.
Results
Proximate analysis
Total amounts of protein, ash and moisture of bulgur
samples are given in Table I. The average protein
contents ranging between 8.2 and 9.9% showed
significant differences ( p,0.05) between samples.
The moisture contents of samples had no difference
(10.4– 11.6%); however, the ash contents significantly
differed in the range of 0.71 – 1.06% ( p,0.05).
Sample S had both the highest protein and ash
contents (9.9 ^0.2 and 1.06 ^0.02%, respectively)
among all samples.
Starch, resistant starch and dietary fibre
Total starch, resistant starch and dietary fibre contents
of bulgur samples are presented in Table II. The
average amount of starch content was in the range of
66.9– 71.6% and the variation between the samples
was found to be statistically insign ificant ( p.0.05).
The amounts of total resistant starch of samples
were found to be between 2.1 and 2.8% (Table II).
Although the total starch amount of samples were not
different from each other, significant differences were
observed in their resistant starch contents ( p,0.05).
Dietary fibre constituent was investigated by
measuring both soluble and insoluble fibre contents.
Total dietary fibre content varied between 5.8 and
8.2% in samples (Table II). The insoluble and soluble
fibre amounts were in the range of 4.2 – 6.6 and 0.3 –
2.2%, respectively (Table II). All fibre components of
samples were found to be significantly different from
each oth er ( p,0.05).
Total phenolics and antioxidant activity
The amount of total phenolics in samples changed
between 55.3 and 62.1 mg Gallic acid/100 g dry matter
with an average of 59.5 ^5.2 mg Gallic acid/100 g dry
matter (Table III). There was no significant difference
in the amount of phenolic compounds between bulgur
Table I. Proximate analysis of bulgur samples
*,†
.
Sample Protein (%) Moisture (%) Ash (%)
S 9.9 ^0.2
a
10.4 ^0.5
a
1.06 ^0.02
a
B 9.6 ^0.2
ab
11.6 ^1.2
a
0.93 ^0.06
ab
F 8.6 ^0.1
c
10.5 ^0.5
a
0.88 ^0.05
b
P 9.3 ^0.0
b
11.6 ^0.2
a
1.04 ^0.0
a
D 8.2 ^0.2
d
11.6 ^0.3
a
0.71 ^0.12
c
Average (%) 9.0 ^0.7 11.2 ^0.8 0.92 ^0.1
*Values represent the mean and SD of three replicates on dry matter
basis;
†
Values with different superscript(s) within a column differ
significantly ( p,0.05).
Z. Tacer Caba et al.252
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samples ( p,0.05). The antioxidant capacity of
bulgur samples is represented in Table III. DPPH
scavenging activities of bulgur samples at 0.005 g/ml
concentration ranged between 20.5 and 25.1%, while
ABTS scavenging values were changing from 457.3
to 613.0 mmol TEAC/100 g dry matter (Table III).
Antioxidant compound
The identified phenolics in bulgur samples comprised
gallic acid, 3,4 hydroxybenzoic acid, epicatechin,
caffeic acid and ferulic acid. A sample HPLC
chromatogram showing the phenolic compounds in
samples is given in Figure 1. That chromatogram was
randomly chosen, as the phenolic compounds present
in each sample were identical.
Discussion
Based on the results of proximate analyses, significant
differences in protein and ash contents of the bulgur
samples might be related to the agricultural practices
during growing wheat. It is known that regional
differences such as fertilizers used in the soil and
annual amount of rain at the place of growth and
cultivar variations might be effective in the difference
of protein levels (Peterson et al. 1986; Tipples et al.
1994). Similarly, the variation in the ash contents
might be related to the production site, dehulling
step and variety differences (Peterson et al. 1986;
Ko¨ksel et al. 1999). On the other hand, the protein
contents of bulgur samples (8.2 –9.9%) were similar to
the findings of Ko¨ksel et al. (1999) who reported
protein contents of raw barley and bulgur made from
barley in the range of 9.5– 11.4%. However, the ash
contents of bulgur samples are lower than those values
(1.11– 1.95%) reported by Ko¨ksel et al. (1999).
Starch, another important component in cereal
products, is categorized into different fractions
based on its digestibility in the gastrointestinal tract
of human beings. Those categories comprise rapidly
digestible starch, slowly digestible starch and resistant
starch (Berry 1986; Englyst et al. 1992). Although
the largest portion of the starch is digested in the
human small intestine, a substantial part escapes into
the large bowel. Based on the process steps, retro-
graded starches that are cooked and cooled constitute
the type of resistant starch found in bulgur (Topping
and Clifton 2001). The average total resistant starch
content (2.5 ^0.3%) was observed to be slightly
higher than that of some common cereals such as
barley, millet, oat and sorghum reported to be between
0.23 and 1.96% (Ragaee et al. 2006). In addition,
bulgur is a richer source of resistant starch than
another cereal product, egg pasta (eris¸te), which has
about 0.56– 1.21% resistant starch content (Akıllıog˘lu
and Yalc¸ ın 2010). On the other hand, resistant starch
content of bulgur is slightly lower than that of cooked
pasta made from Emmer wheat (2.79%; Fares et al.
2008). Factors such as chemical structure of food,
cooking process, chemical modification and food
mastication are common reasons for the occurrence
of resistant starch (Topping and Clifton 2001). In
addition, wheat variety, wheat milling and processing
conditions have important roles on the distribution
of each starch category, namely rapidly digestible
starch, slowly digestible starch and resistant starch,
in products (Ragaee et al. 2006).
Previous studies revealed that thermal treatment
could affect the ratio of soluble – insoluble fractions of
Table III. Total phenolics and antioxidant activity of bulgur samples
*,†
.
Sample Total Phenolics (mg Gallic acid/100 g) ABTS (mmol TEAC/100 g) DPPH (Scavenging activity %)
S 62.1 ^6.3
a
596.6 ^12.0
a
22.0 ^3.8
ab
B 61.6 ^2.7
a
600.7 ^16.2
a
21.0 ^1.1
b
F 61.0 ^2.8
a
550.1 ^13.4
b
22.2 ^0.7
ab
P 57.8 ^6.6
a
613.0 ^12.4
a
25.1 ^1.2
a
D 55.3 ^6.2
a
457.3 ^25.0
c
20.5 ^2.2
b
Average 59.5 ^5.2 563.3 ^60.7 22.2 ^2.4
*Values in columns represent the mean and SD of three replicates on dry matter basis;
†
Values with different superscript(s) within a column
differ significantly ( p,0.05).
Table II. Total starch, resistant starch and dietary fibre contents of bulgur samples
*,†
.
Sample Starch (%) Resistant Starch (%) Soluble Dietary Fibre (%) Insoluble Dietary Fibre (%) Total Dietary Fibre (%)
S 70.3 ^6.7
a
2.2 ^0.3
cd
0.5 ^0.3
bc
5.3 ^0.5
b
5.8 ^0.7
b
B 66.9 ^3.2
a
2.1 ^0.2
d
0.3 ^0.1
c
6.0 ^0.2
ab
6.2 ^0.0
b
F 68.9 ^1.2
a
2.8 ^0.2
a
2.2 ^0.2
a
6.1 ^0.4
a
8.2 ^0.7
a
P 69.2 ^2.9
a
2.7 ^0.0
ab
0.7 ^0.4
bc
6.6 ^0.4
a
7.3 ^0.1
a
D 71.6 ^1.0
a
2.5 ^0.1
bc
1.8 ^0.4
ab
4.2 ^0.3
c
6.0 ^0.7
b
Average (%) 69.3 ^3.1 2.5 ^0.3 1.2 ^0.8 5.6 ^0.9 6.8 ^1.0
*Values in columns represent the mean and SD of three replicates on dry matter basis;
†
Values with different superscript(s) within a column
differ significantly ( p,0.05).
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dietary fibre depending on the type of the cereal and
process conditions utilized. For example, the increase
in the insoluble dietary fibre content of durum wheat
kernel fractions (7 – 10%) has been related to the
gelatinization and the retrogradation of the starch
during cooking-extrusion process (Esposito et al.
2005). On the other hand, Caprez et al. (1986)
reported a change in the surface properties of dietary
fibre of wheat bran samples after thermal treatments
such as boiling and autoclaving (Caprez et al. 1986).
Therefore, processing of bulgur involving heat
applications may also be responsible for the observed
differences in the amounts of dietary fibre com-
ponents. In general, the total dietary fibre contents of
bulgur samples are higher than those of some cereal
products such as couscous (an average of 6.8 ^1.0
per 100 g; C¸ elik et al. 2004) and egg pasta (eris¸te)
(3.6– 6.3%; Akıllıog˘ lu and Yalc¸ ın 2010).
Beside dietary fibre and resistant starch, grain
products are also sources of phenolic compounds as
well. They are important contributors to antioxidant
activity in cereals. Previous literature revealed that
quantity of phenolics in different species of wheat
samples may differ significantly depending on the
location of growth (Gelinas and McKinnon 2006).
Similarly, total phenolics in cereal products were
found to be associated with the type, species or part of
the sample investigated in another study (Liu 2007).
The results of the present study are in line with the
results of other studies carried out in cereal
commodities. It was reported that hard and soft
wheat flours contained 56.2 and 50.1 mg Gallic
acid/100 g dry matter of phenolic compounds (Ragaee
et al. 2006). Yu et al. (2002) showed that the amount
of total phenols in three wheat samples was in the
range of 48.7 –92.7 mg Gallic acid/100 g dry matter
(Yu et al. 2002). Those results were also supported
by other researchers who presented about 40 –80 mg
Gallic acid/100 g dry matter of phenolic compounds
in eight wheat varieties grown in Maryland (Moore
et al. 2005).
For the antioxidant activity determination, DPPH
and ABTS radical scavenging methods were used.
Antioxidant capacities of bulgur samples are higher
(457.3– 613.0 mmol TEAC/100 g dry matter) than
those reported in some wheat varieties of Colorado
by Yu et al. (2002). On the other hand, the DPPH
scavenging activities of the same samples are found
to be higher than bulgur samples. For example,
Akron sample extract was detected to scavenge 92.9%
DPPH radicals for a concentration level of 0.002 g/ml
(Yu et al. 2002). In addition, the ABTS radical
scavenging activities reported by Ragaee et al. (2006)
(average of hard and soft wheat samples: 855 mM
ABTS/100 g sample) and Moore et al. (2005) (eight
different varieties of soft wheat grains: 1430 –1760 mM
TEAC/100 g sample) are higher than those of
bulgur samples. In addition, there was no significant
correlation detected between the amount of total
phenolics and antioxidant activity for ABTS
(r¼0.284, p,0.05) and DPPH (r¼20.064,
p,0.05). This finding was supported by the study
of Yu et al. (2002) who found no correlation between
the free radical scavenging properties and total
amount of phenolics of three winter wheat varieties
(Akron, Trego and Platte) grown in Colorado.
On the other hand, antioxidant activity measured
by ABTS method correlated significantly with the
AU
0.000
0.008
Minutes
6.00
162
3
66
654
66
8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00 40.00
5.314
10.150
12.570
21.917
27.243
33.512
AU
0.000
0.002
0.004
Minutes
6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00 40.00
5.050
12.480
22.762
31.511
33.523
HPLC chromatogram of P1 sample at 280 nm(a)
(b) HPLC chromatogram of P1 sample at 320 nm
Figure 1. HPLC chromatograms of sample P1. Phenolic compounds in samples were coded in numbers (1), gallic acid; (2), 3,4
hydroxybenzoic acid; (3), epicatechin; (4), caffeic acid; (5), ferulic acid and (6), undefined component.
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insoluble dietary fibre (r¼þ0.764) and soluble
dietary fibre (r¼20.680) contents of samples
(p,0.05). These findings are in alignment with
claims indicating that the antioxidant capacity of
cereal products and their dietary fibre contents are
particularly associated with the phenolic compounds
(Fardet et al. 2008; Vitaglione et al. 2008).
HPLC analysis produced a more detailed profile
of the phenolic compounds found in bulgur samples
by determining them individually. The presence of
phenolic compounds detected (gallic acid, 3,4 hydro-
xybenzoic acid, epicatechin, caffeic acid and ferulic
acid) is consistent with the previous findings (Sosulski
et al. 1982; Yu and Cheng 2008) showing the
availability of other phenolic compounds such as
trans-ferulic acid, syringic acid, vanillic acid, sinapic
acid and coumaric acid in wheat. Similar to these
results, the presence of ferulic acid, p-coumaric,
vanillic and sinapic acids in two types of wheat,
wheat bran and flour samples was also reported
(Liyana-Pathirana et al. 2006). In wheat bran, ferulic
acid, p-hydroxybenzoic acid and vanillic acid were
reported to be major phenolic compounds (Kim et al.
2006). Some researchers reported the presence of
ferulic acid, diferulic acid, sinapic acid, p-coumaric
acid and benzoic acid derivatives as phenolic
structures in different wheat fractions collected after
the milling process (Gallardo et al. 2006).
Conclusion
This study enhances our knowledge about bioactive
components of bulgur in addition to the minerals,
vitamins and other nutrients. Healthy potential of
bulgur is clearly demonstrated through functional
bioactive components such as dietary fibre, resistant
starch, total phenolic constituents and antioxidant
capacity. It is apparent that bulgur, a whole wheat
product, is a healthy choice representing a great
potential as a cereal-based product.
Declarations of interest: This project was supported
by Istanbul Technical University Institute of Science
Graduate Study Support Fund. The authors report no
conflict of interest. The authors alone are responsible
for the content and writing of the paper.
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