Physiochemical and functional properties of barley b-glucan as affected by different extraction procedures

Original article
Physicochemical and functional properties of barley b-glucan as
affected by different extraction procedures
Asif Ahmad,1
* Faqir Muhammad Anjum,2
Tahir Zahoor,2
Haq Nawaz3
& Ahmad Din2
1 Department of Food Technology, University of Arid Agriculture Rawalpindi, Shamsabad, Muree Road, Rawalpindi, 46300, Pakistan
2 National Institute of Food Science and Technology, University of Agriculture, Faisalabad, 38040, Pakistan
3 Institute of Animal Nutrition and Feed Technology, University of Agriculture, Faisalabad, 38040, Pakistan
(Received 20 July 2007; Accepted in revised form 17 December 2007)
Summary Four methods were evaluated for extraction of b-glucan from barley. Gum pellets obtained by respective
methods were examined for yield, purity and various physicochemical and functional characteristics. Highest
yield and recovery was found in samples that were extracted by hot water treatment. This method also
removed the maximum impurities from gum pellets and contained highest amount of soluble fibre, while
alkali-extracted sample contained highest amount of insoluble fibre. All samples contained an appreciable
amount of calcium and phosphorus. Extracted pellets had good water retention and foaming capacity.
A significant variation in extraction methods was observed with respect to water binding capacity and foaming
capacity. However, the same level of foaming stability was observed in all extraction methods. Alkaline and
acidic extraction methods adversely affect the viscosity properties of the samples. A significant affect of
extraction methods was also observed on colour parameters of b-glucan. A negative correlation exists between
foaming capacity and viscosity, whereas a positive correlation observed between soluble fibre and viscosity.
Keywords b-Glucan, barley, dietary fibre, extraction methods.
Introduction
Barley is an important cereal food all over the world. It
is abundantly used in Africa, Asia and semi-arid tropics
and is also cultivated in Europe, America and Australia.
This crop is currently used as feed for animals as well as
food for human consumption. Certain new applications
of this cereal crop are under investigation for new value-
added products (Keogh et al., 2003; Erkan et al., 2006).
There is a variety of food applications of barley being
used in Pakistan, India, China, West Asia and North
Africa region.
In recent years, the importance of barley grains as a
nutraceutical ingredient has increased because of their
high contents of soluble fibre, especially as a rich source
of b-glucan. Because of its nutritional and chemical
properties in particular a high dietary fibre content and
high proportion of soluble viscous dietary fibre compo-
nent, barley is considered the most suitable grain in
human diet. Many health agencies also encourage an
increase fibre intake (American Diabetes Association,
1999). The most documented nutritional benefit of
b-glucan in foods is flattening of postprandial blood
glucose (Cleary & Brennan, 2006) and insulin rises (Liu
et al., 2002). The Food and Drug Administration
(FDA) has acknowledged nutritional claims that the
use of dietary fibres (including Barley b-glucan) reduces
the glycemic and cholesterol responses of individuals.
Current recommendations suggest an intake of 20–40 g
of dietary fibre per day (Devries et al., 1999). The FDA
has adopted a recommendation of 3 g day)1
of b-glucan
as having a nutritional effect (FDA, 1997).
Owing to its physiological benefits, dietary fibre of
barley (mainly b-glucan) has drawn much attention
recently, particularly in the growing nutraceutical indus-
try. This non-starchy polysaccharide is composed of
(1 fi 3), (1 fi 4) mixed linked glucose polymers. Most of
their quantities are concentrated in cell walls of endo-
sperm (Miller & Fulcher, 1994). Some factors, such as
cultivar and location, have a significant influence on
quantity and extraction of b-glucan (Yalcın et al., 2007).
The cell wall of these cereals also contains starch, protein
matrix, fats and minerals along with b-glucan; thus, the
extraction and purification process requires special tech-
niques for maximum recovery and purity. The choice of
extraction procedures affects the yield, purity, structure
and integrity of b-glucan molecule. Various extraction
procedures developed by different scientists and used in
lab scale are: hot water extraction, enzymatic extraction
(Irakli et al., 2004), solvent extraction (Bhatty, 1993) and*Correspondent: E-mail: asifahmad_1@hotmail.com
International Journal of Food Science and Technology 2009, 44, 181–187 181
doi:10.1111/j.1365-2621.2008.01721.x
Ó 2008 Institute of Food Science and Technology Trust Fund

alkali extraction (Wei et al., 2006). A hot water extrac-
tion procedure in the presence of thermo stable a-amylase
to minimise the contamination from starch and to
optimise the purification of the b-glucan material has
also been used (Saulnier et al., 1994). The effect of
extraction conditions on yield, composition and viscosity
of barley gum was also evaluated. A small modification in
extraction procedure may have profound affect on
functional behaviour, composition, viscosity, colour,
molecular weight and the physicochemical properties of
the extracted b-glucan (Burkus & Temelli, 1998).
Relatively little work has been reported on rheological
and functional properties (viscosity, water binding
capacity (WBC), whippibilty, foaming capacity, etc.).
Similarly, little or no work has been published on
foaming capacity of b-glucan and their relationship with
extraction procedures, which in turn can affect the
nutritional, sensory and physiological characteristics of
the food products in which b-glucan is incorporated as
ingredient.
The objective of this study was to compare efficiency
of different extraction procedures for recovery, yield and
composition, and to investigate various functional
properties of b-glucan extracted.
Materials and methods
Sample material
Covered barley of local cultivar was received from Ayub
Agricultural Research Institute, Faisalabad. Whole
barley was milled in a high-speed electric mill equipped
with 0.50-mm screen.
b-glucan extraction
b-Glucan was extracted from whole barley flour by four
methods. In first method (M1), alkaline extraction that
make use of NaOH was used; in second method (M2),
acidic extraction procedure that employ citric acid was
used; in third method (M3), hot water extraction was
done and in fourth method (M4), enzymes were used to
facilitate extraction. A schematic outline of the extrac-
tion protocols is presented in Fig. 1.
All analyses were determined on the extracted b-glu-
can gum. Furthermore, moisture, ash, starch, crude fat,
protein and dietary fibre were determined for the barley
flour.
Chemical analysis
Moisture, ash and crude fat contents of flour and
extracted gum material were determined according to
the approved methods of the American Association of
Cereal Chemists Method 44-16, Method 08-01 and
Method 30-10, respectively (AACC, 2003). Nitrogen
contents for barley flour and gum samples were deter-
mined by the Kjeldahl method (AACC, 1990) and
converted to protein content by a factor of 6.25. Starch
contents were determined according to Method 76.13
(AACC, 2003). Minerals contents were determined by
atomic absorption spectrometry following the method
as described in AOAC (1990).
b-glucan assay
b-Glucan assay was conducted according to the method
of McCleary & Glennie-Holmes (1985) using the b-glu-
can enzymatic assay kit (Megazyme International
Ireland Ltd, Wicklow, Ireland). b-Glucan contents of
gums were reported on moisture-free basis.
Total, insoluble and soluble fibre
Total, insoluble and soluble fibres were quantified
through small modification in enzymatic gravimetric
procedure of AACC Method 32-05, 32-20 and 32-07,
respectively (AACC, 2003), by employing Megazyme
assay kit (Megazyme International Ireland Ltd).
Colour measurement
The colour of b-glucan samples was measured using the
L*, a* and b* colour space (CIELAB space) with Color
Tech-PCM (Accuracy Microsensors Inc., Pittsford, NY,
USA). The L* value indicates lightness, the a* and b*
values are the chromaticity coordinates (a* from green
to red; b* from blue to yellow). The reported values are
the means of three replicates.
Foaming properties
The foaming capacity and foam stability (FS) were
studied using the method of Temelli (1997). Gum
material (2.5 g, containing b-glucan) was dissolved in
100 mL distilled water. The resulting solution was mixed
vigorously for 2 min using a hand-held food mixer at
high speed in a stainless steel bowl with straight sides
and volumes were recorded before and after whipping.
The percentage volume increase (which serves as index
of foam capacity) was calculated according to the
following equation:
% Volume increase =
ðV2ÀV1Þ
V1
Â 100
where V1 is the volume of solution before mixing and V2
is the volume of solution after mixing.
To determine FS, foams were slowly transferred to a
1000-mL graduated cylinder and the volume of foam
that remained after staying at 25 ± 2 °C for 2 h was
expressed as a percentage of the initial foam volume.
Water binding capacity
The WBC of samples was measured by the modified
method described by Wong & Cheung (2005). Twenty
Physicochemical and functional properties of barley b-glucan A. Ahmad et al.182
International Journal of Food Science and Technology 2009, 44, 181–187 Ó 2008 Institute of Food Science and Technology Trust Fund

millilitre of distilled water was added into a centrifuge
tube containing 200 mg b-glucan. After which it was
placed in a shaker at 25 °C for 12 h, the tubes were
centrifuged at 14000 · g for 30 min at 25 °C. The
supernatant (unbound water) was discarded, and the
amount of water held in the hydrated sample was
determined by heating the pre-weighed pellet in a hot air
oven for 2 h at 120 °C. The WBC of each sample was
expressed as the weight of water held by 1.0 g of
b-glucan sample.
Viscosity measurement
For viscosity measurements, 1% (w⁄v, as is basis)
dispersion of b-glucan gum in deionised water was
prepared by heating mixtures at 100 °C for 10 min
followed by stirring on magnetic stirrer at 30 °C for 2 h
and adjusting pH at 7.0. Viscosity was measured using a
Rion viscometer (Rion Co., Ltd, Boston, MA, USA).
Changes in viscosity (1% solution of b-glucan) at
various temperatures were also monitored.
Statistical analysis
The data were analysed for variance using the mstat
statistical package (Michigan State University, Michi-
gan, USA) when significant differences were found, the
least significant difference (LSD) test was used to
determine the differences among means (Anon., 1988).
M1 M2 M3 M4
Acidic Extraction Enzymatic Extraction
100 g flour
Refluxing with 80%
ethanol for 6 h
Mixing the Flour with 1
M NaOH in 1:7 ratio
Mixing on hot plate with
magnetic stirrer for 90
min at 55°C
Centrifuge at 15000 g
for 20 min at 40°C
Supernatant taken &
mixed with 1 M NaOH in
1:3 ratio
Centrifuged at 18000 g
for 20 min at 40°C
Supernatant adjusted at
pH 7 with citric acid
for 25 min
Mix Supernatant +
Ethanol (80%) in 1:1
ratio & hold for 20 min
Centrifuged at 4000 g at
4°C
Dry pellets in vacuum
oven
100 g flour
Refluxing with
80% ethanol for
6 h
Mixing the Flour with
1 M Citric acid in 1:7
ratio
Mixing on hot plate
with magnetic stirrer
for 90 min at 55°C
for 20 min at 40°C
Supernatant taken &
mixed with 1 M citric
acid in 1:3 ratio
Centrifuged at 18000
g for 20 min at 40°C
Supernatant was
neutralized at pH 7
with NaOH
Centrifuged at 21000
g for 25 min
Mix Supernatant +
Ethanol (80%) in 1:1
ratio & hold for 20
min
at 4°C
oven
100 g flour
Refluxing with 80%
ethanol for 6 h
Mixing the Flour with
water in 1:10 ratio
High speed stirring on hot
plate with magnetic stirrer
for 90 min at 55°C
Centrifuge at 15000 g for
20 min at 40°C
Supernatant adjusted at pH
8.5 with sodium
bicarbonate and stirred on
hot plate for 30 min at 55°C
Centrifuged at 18000 g for
20 min at 40°C
Supernatant was adjusted
at pH 4 with citric acid
Centrifuged at 21000 g for
25 min
Mix Supernatant + Ethanol
(80%) 1:1 and hold for
20 min
oven
100 g flour
Refluxing with
80% ethanol for
6 h
Treated with heat stable
alpha amylase at 40°C &
incubated for 3 h
for 20 min at 40°C
Supernatant was treated
with protease enzyme at
37°C & incubated for 3 h
for 25 min at 4°C
Mix Supernatant +
Ethanol (80%) 1:1 and
hold for 20 min
4°C
oven
Alkaline Extraction Hot water Extraction
4°C
Figure 1 Extraction and purification schemes
of b-glucan from barley flour.
Physicochemical and functional properties of barley b-glucan A. Ahmad et al. 183
Ó 2008 Institute of Food Science and Technology Trust Fund International Journal of Food Science and Technology 2009, 44, 181–187

Results and discussion
Chemical composition of barley flour
The chemical composition of whole barley flour was
determined on moisture free basis. Whole barley flour
contained starch 54.2%, crude fat 2.42%, total ash
2.92%, protein 14.2%, soluble dietary fibre 2.86%,
insoluble dietary fibre 10.24% and total dietary fibre
13.1%. It was obvious that barley flour is a good source
of dietary fibre that can be used as beneficial functional
ingredient in various food products.
Gum yield and b-glucan recovery
Yield of gum product represent the weight of gum
obtained from 100 g of flour. Yield of gum ranged from
3.94% to 5.40% in different extraction procedures.
Highest yield of 5.4% was obtained when hot water
extraction procedure was used followed by 5.22% when
enzymatic extraction procedure was used, acidic process
gave a yield of 4.65%, whereas lowest yield (3.94%) was
experienced in alkaline extraction procedure. This gum
did not represent the whole quantity of b-glucan. In
addition to b-glucan, this gum also contained some fat,
protein, starch and minerals (ash). Therefore, to deter-
mine the efficiency of various extraction methods, b-glu-
can recovery was calculated. b-Glucan recovery
corresponds to the percentage ratio of weight of b-glucan
in gum product (that was obtained from 100 g flour) to
the weight of b-glucan actually present in 100 g flour and
it shows the efficiency of purification process of b-glucan.
The percentage yield obtained was 3.94%, 4.65%, 5.4%
and 5.22% for M1, M2, M3 and M4, respectively. As
concerned with recovery of b-glucan, highest recovery
(83.1%) was obtained in hot water extraction method
followed by 81.4% and 80.4% in enzymatic and acidic
extraction process. Least recovery (78.1%) was obtained
in alkaline extraction process. Previous studies had
reported a recovery of 57.8%–88.4% when different pH
and temperatures conditions were used for extraction of
b-glucan (Temelli, 1997; Burkus & Temelli, 1998).
Symons & Brennan (2004a) observed a lower efficiency
of hot water extraction because of b-glucan cleavage by
b-glucanase enzyme. In the present study, a preliminary
treatment through refluxing with 80% ethanol inacti-
vated the b-glucanase enzyme, this resulted in higher
recovery. Another reason for relatively higher recovery in
hot water extraction process may be due to higher
gelatinisation of starch and solubilisation of proteins.
Moreover, indigenous enzyme system was inactivated.
Chemical composition of b-glucan
The chemical composition of b-glucan gum is presented
in Table 1. The starch contents of b-glucan gum ranged
from 3.19% to 3.75%. Highest amount of beta glucan
starch (Bg-starch) was observed when alkaline extrac-
tion procedure was adopted, whereas lowest amount
(3.19%) was observed in enzymatic extraction proce-
dure. This showed in-efficiency of alkali to remove
starch material from the gum material. The other
extraction methods in this study favoured the removal
of starch from the gum material with no significant
difference (P < 0.05). The enzymatic extraction process
reduced starch contents because of action of thermo
stable a-amylase. A negative correlation (r = )0.752)
was observed between b-glucan contents and starch
contents of b-glucan pellets (Table 4). As expected all
methods appreciably removed fatty portion and statis-
tically a non-significant difference was observed with
respect to removal of fat from different extraction
methods. The oxidative degradation of fat is important
when taken into consideration during processing and
storage. This may result in production of bitter com-
pounds (Molteberg et al., 1995), hence can deteriorate
the quality of product in which b-glucan will be added as
functional ingredient. Protein contents varied substan-
tially (P < 0.05) among the samples and ranged from
6.90% to 7.72% (Table 1). A higher amount of protein
was obtained when hot water extraction was used for
extraction of b-glucan. The iso-electric point of protein
in acidic range favours the removal of more proteina-
ceous matter in acidic extraction process. Similarly,
more protein removal in enzymatic extraction process
was due to action of protease enzyme. Protein contents
of b-glucan may affect the various functional character-
istics of product in which b-glucan is added as
functional ingredient. As concerned the mineral (ash)
contents of b-glucan gum, acid extraction and hot water
extraction method had similar effect but varied from
alkaline extraction and enzymatic extraction methods.
Highest value was observed in enzymatic extraction
process followed by alkali extraction. Detailed mineral
Table 1 Chemical analysis of b-glucan gum pellets
%
Starch
%
Crude fat
%
Protein
%
Ash
%
SDF
%
IDF
%
TDF
M1 3.75 a 0.71 a 7.31 ab 1.40 a 82.23 d 8.56 a 91.20 b
M2 3.24 b 0.56 a 6.86 b 1.26 b 84.25 c 7.50 b 93.20 a
M3 3.23 b 0.83 a 7.72 a 1.15 b 88.70 a 5.78 d 94.25 a
M4 3.19 b 0.72 a 6.90 b 1.42 a 86.63 b 6.76 c 93.57 a
CV (%) 5.09 20.22 5.61 5.24 0.95 5.14 1.11
LSD 0.32 0.39 0.76 0.13 1.53 0.69 1.95
M1 = alkaline extraction method; M2 = acid extraction method; M3 = hot
water extraction method; M4 = enzymatic extraction method.
SDF, soluble dietary fibre; IDF, insoluble dietary fibre; TDF, total dietary
fibre.
Values sharing the same letter within a column is non-significant
(P < 0.05).

profile (Table 3) of b-glucan showed that an appreciable
amount of phosphorus and potassium is present in all
samples.
Analysis of dietary fibre in gum pellet
The fibre composition (soluble, insoluble and total
dietary fibre) is presented in Table 1. Major component
of dietary fibre are arabinoxylan, arabinogalactan,
cellulose, b-glucan, lignin, pentosan and resistant starch.
These dietary fibres are often categorised into soluble
and insoluble dietary fibres. Most of the part of b-glucan
consisted of soluble dietary fibre. These fibres reduce the
release of sugars and are responsible for reduced
glycemic index (Cavallero et al., 2002; Symons &
Brennan, 2004b). In samples of extracted gums, soluble
dietary fibre ranged between 82.23% and 88.70%.
Highest amount of soluble dietary fibre was observed
in hot water extraction method.
These gums pellets contain relatively low amount of
soluble fibre when extracted by use of alkali. A similar
observation was reported in the literature that b-glucan
contents decreased at high pH and high temperature
(Temelli, 1997). All the methods contained a higher
amount of soluble fibre as compared with insoluble
dietary fibre. A highly negative relationship was also
observed between soluble and insoluble fibres (Table 4).
Highest amount of insoluble fibre was observed in alkali
extraction process, whereas water extraction method
discourages the concentration of insoluble fibre material
in gum pellets.
Colour of b-glucan
The data on colour of b-glucan containing gum pellets
was recorded using CIE lab colour space and are
presented in Table 2. A highly significant (P < 0.05)
difference was observed in all samples. Samples ex-
tracted by hot water extraction procedure possessed
significantly (P < 0.05) higher values of lightness (L*)
but slightly lower values of redness (a*) and yellowness
(b*). Such a high degree of lightness had a technolog-
ically favourable advantage when the raw ingredient
(b-glucan) has to be added in light or transparent colour
food products because their incorporation would not
likely give off colours or darker colours to these food
products. Relatively lower value was observed in enzy-
matic extracted sample, whereas a* value of other
samples was higher and statistically non-significant
(P < 0.05). As concerned with b* values, it varied
significantly (P < 0.05) in all samples and alkali
extracted b-glucan got maximum b* value. Correlation
study (Table 4) indicates a highly positive correlation
between L* value and soluble fibre while a highly
negative correlation exist between insoluble fibre and L*
value. This observation suggests that soluble fibre
impart more lightness to product.
Water binding capacity
The WBC of a fibre measures the amount of water
retained by the fibre after subject to stress such as
centrifugation. These hydration properties of barley
b-glucan are important in many food applications and
have an impact on shelf life of food product. The data
on WBC are presented in Table 2. b-Glucan extracted
by hot water treatment had highest value of WBC
(3.79 g g)1
dw) followed by alkali and acid extracted
b-glucan, which is statistically comparable (P < 0.05).
Table 3 Minerals profile of b-glucan containing gum pellets (mg kg)1
)
Minerals P K Mg Ca Na Zn Fe Mn Cu
M1 3040 3290 960 360 230 72.5 32 8.3 6.5
M2 2918 3206 858 280 166 76.3 29 7.8 6.3
M3 3010 3318 762 262 142 72.3 28 7.5 6.2
M4 3272 3242 902 292 174 82.5 34 8.5 7.2
Table 2 Functional characteristics of b-glucan
Viscosity
(cP)
Water
binding
capacity
(g g)1
)
Foaming
capacity
(%)
Foam
stability
(%) L* a* b*
M1 34.30 d 3.28 b 160 b 68.20 a 67.55 d 7.70 a 21.50 a
M2 38.80 c 3.10 c 148 c 64.10 a 69.86 c 8.39 a 18.08 c
M3 50.27 b 3.79 a 172 a 66.20 a 77.34 a 7.45 ab 16.22 d
M4 52.82 a 2.91 d 122 d 65.20 a 71.48 b 6.75 b 19.32 b
CV (%) 1.09 1.95 2.16 4.37 1.15 6.80 2.51
LSD 0.90 0.12 6.12 5.41 1.55 0.97 0.89
Values sharing the same letter in a column is non-significant (P < 0.05).
Table 4 Correlation among various parameters
Bg-starch b-glucan Sol Insol L* Visc WBC FOC
Bg-starch 1.00 )0.75 )0.74 0.75 )0.57 )0.66 0.09 0.29
b-Glucan 1.00 0.79 )0.75 0.69 0.80 0.07 )0.24
Sol 1.00 )0.93 0.92 0.87 0.41 0.02
Insol 1.00 )0.90 )0.84 )0.40 )0.08
L* 1.00 0.73 0.67 0.34
Visc 1.00 0.08 )0.34
WBC 1.00 0.88
FOC 1.00
Bg-starch, b-glucan starch; Sol, soluble fibre of gum pellets; Insol,
insoluble fibre of gum pellets; L*, lightness of colour of gum pellets; Visc,
viscosity; WBC, water binding capacity; FOC, foaming capacity.

A slightly lower value of WBC was observed in samples
that were extracted enzymatically. The values obtained
in this study for WBC are comparable to that of some
other dietary fibres derived from processing of by
products [sugar beet fibre 4.56 g g)1
, wheat bran
2.6 g g)1
, corn bran 2.5 g g)1
and soybean bran
2.4 g g)1
(Dreher, 1987)]. The high value of WBC for
b-glucan in hot water extraction procedure suggested
that this material could be used successfully as a
functional ingredient to avoid syneresis problem in
various food products such as jam, jellies, sauces and
cheese. A negative correlation was found (Table 4)
between WBC and insoluble fibre that suggested that
WBC of b-glucan gum is due to soluble portion of
dietary fibre. A highly positive correlation was experi-
enced between WBC and foaming capacity (r = 0.87).
These two properties (WBC and foaming capacity) are
important in formulation of many products and give
shelf stability to final food products.
Viscosity
The data regarding viscosity of 1.0% w⁄v solution of
b-glucan determined at 20 °C are presented in Table 2.
The main contributor of viscosity in gum pellet was
b-glucan. The viscosity of b-glucan sample ranged from
34.30 to 52.82 cP in different samples extracted by
different extraction procedures. Highest value of viscos-
ity (52.82 cP) was found in enzymatic extracted b-glucan,
whereas lowest was found in alkali-extracted b-glucan.
The low viscosity in alkali-extracted b-glucan was due to
depolymerisation of linear structure of b-glucan
(Brennan & Cleary, 2005). A previous study on viscosity
also indicated similar results (Bhatty, 1995), which
reported that very high extraction pH of 1 m NaOH
solution resulted in lower viscosity of oat b-glucan. This
reduced viscosity may be due to the sensitivity of (1 fi 3)-
b-D bond to high pH (McCleary & Codd, 1991).
Temperature and pH of solution also affect the viscosity
of b-glucan solution. Changes in viscosity (Fig. 2) are
apparent with a gradual increase in the temperature of
1.0% w⁄v solution of b-glucan. A highly positive
correlation can be seen (Table 4) between viscosity and
high b-glucan contents; similarly, soluble fibre tends to
increase viscosity (r = 0.86), whereas insoluble fibre has
a tendency to lower the viscosity (r = )0.84).
Foaming capacity and foam stability
The data on foaming capacity and FS is presented in
Table 2. These functional properties are important when
b-glucan is to be used as a functional ingredient and
stabiliser in batters, often a high foaming capacity and
stability is desirable in cakes and batters. In this study,
different extraction methods had a significant (P < 0.05)
affect on foaming capacity of b-glucan. A higher foaming
capacity was observed when sample was extracted by hot
water extraction procedure. Higher foaming capacity in
hot water extraction process may be due to relatively
higher protein contents that trapped more air to develop
more foam. Once the foam was established there existed
a non-significant (P < 0.05) difference with regard to its
stability in all samples. A negative correlation is found
(Table 4) between foaming capacity and viscosity, which
shows that viscosity imparted by b-Glucan, makes the
liquid to foam with difficulty.
Conclusions
In this study, various extraction methods had a signif-
icant affect on recovery and most of the physicochemical
properties of extracted b-glucan. Hot water extraction
yielded a higher yield and recovery of b-glucan. Current
study also revealed that extraction methods had an
impact on dietary fibre contents of extracted b-glucan.
While for crude fat, non-significant (P < 0.05) differ-
ence was observed. Relatively less starch and protein
impurities were observed in enzymatic and acidic
extraction methods, respectively. A higher water binding
and foaming capacity was found in hot water extraction
method while foaming stability (in this study) was not
affected by extraction methods. Highest viscosity was
observed in samples of b-glucan that were extracted by
enzymatic extraction process. All extraction methods
yielded a light colour b-glucan gum; however, high
degree of lightness (L* value) was observed in hot water
extracted b-glucan. On the basis of physicochemical
properties, all extraction methods in the present study
showed a great potential for production of b-glucan
gum. However, on cumulative basis, b-glucan extracted
from hot water extraction method seemed to be a cheap
and promising additive and have a great potential to be
used in food products.
Acknowledgment
This present study was supported by Higher Education
Commission, Pakistan.
Effect Of temperature on viscosity of
1.0 % (w/v) ββ-Glucan gum
0
10
20
30
40
50
60
20 30 40 50
Temperature (ºC)
Viscosity(cP)
M1
M2
M3
M4
Figure 2 Effect of temperature on viscosity of b-glucan gum solution.

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