CHAPTER-2
REVIEW
OF
LITERATURE
Cereal β -glucan is a soluble dietary f iber and offers
potential for food products. The beverages are one of the best
media for incorporat ion of β -glucan. The characteristic propert ies
desired in the beverage such as color, f lavor and mouth feel make
the barley β -glucan an ideal grain over other cereals , such as
sorghum and wheat (Bamforth and Barclay, 1993). I t a lso exhibits
some health benef its such as lowering of blood glucose level and
prevention of cardiovascular diseases. By manipulat ing the β -
glucan and protein contents of bar ley, numerous types of malt
(beer) and other beverages are l ikely to sat isfy various human
tastes (Munk, 1981).
The l i terature pertaining to different aspects of the present
study is reviewed under fol lowing headings:
2.1 . Barley: History, composit ion and types
2.2 . Role of dietary f iber
2.3 . β -glucan: Sources and occurrence
2.4 . β -glucan extract ion
2.5 . Health benefits of β -glucan
2.6 . Functional propert ies of β -glucan
2.7 . Util izat ion of β -glucan in food products
2.8 . Physico-chemical characteristics of beverages
2.1 . Barley: History, composit ion and types
The cereals are defined as edible seeds of the grass family,
Gramineae (Bender and Bender, 1999). The cereals are cult ivated
for their nutrit ious edible seeds, often referred as grains, and
used as staple food for the human consumption and l ivestock feed
since the early civ il izat ion (BNF, 1994). Cereal grains contribute
significant amounts of energy, protein and micronutr ients to the
human diet and contain a large number of biologically act ive
substances, including antioxidants, dietary f iber, phytoestrogens
and l ignans (Hil l and Path, 1998).
Barley (Hordeum vulgare L . ) competes with wheat regarding
the most ancient cereal crop. I t referred as the original ancient
cereal grains consumed around the world throughout the history.
Barley has been recorded as being cult ivated along the Nile River
thousands of years ago, dating back to Egyptian t imes (Wendorf et
a l . , 1979). Barley is an old crop and its cult ivat ion, mentioned in
the Bible. Due to i ts cold, drought, a lkali and salt tolerance, i t is
grown at 70°N lat i tude in Norway, as well as in regions close to
the equator at high alti tudes (Poehlman, 1985). With respect to
world cereal grain production, bar ley ranks fourth fol lowed by
wheat, r ice and corn (Nilan and Ullrich, 1993). Barley is a major
crop for malt ing, brewing and for food production industries in
the developed countries and it i s ut i l ize as fodder crop in the less
developed and developing countries (Kent and Evers, 1994).
Barley is a typical cereal grain composed primarily of starch,
protein, f iber, l ipids and minerals . The typical composit ion of
barley is outl ined in Table 2 .1 (MacGregor and Fincher, 1993).
Barley is a source of protein, typically contains 10-12% in the
whole grain containing more of the essential amino acids
part icularly lysine, which is the f i rs t l imiting amino acid in the
wheat (Chung and Pomeranz, 1985). Barley proteins can be
grouped as storage and non-storage proteins. Storage proteins
include the prolamins (hordeins) and globulins, as defined by
Osborne protein classif icat ion (Shewry, 1993). Being h igh
molecular weight , water soluble polymers, they have unique
propert ies with both nutrit ional and technological s ignificance.
They are not digested by mono gastric animal which is one reason
for the low use of barley as poult ry feed (Wood, 1984). I t has
recently been rediscovered as a nutrit ious food grain for the
human diet and is expected to see some increase in food
applications in the near future. The s tarch port ion of the grain is a
good source of digest ible carbohydrate, necessary for energy
(MacGregor and Fincher, 1993) .
There are generally two types of barley hulled and hul l-less
barley. Hull- less barley contains more protein, starch, and β -
glucan than hulled barley. I t is a good source of f iber in general
and of soluble fiber, such as β -glucan, in part icular (Bhatty, 1999).
Most of the barley used in the world today is covered (Hulled), as
covered barley is preferred in brewing industry. Naked barley is
therefore advantageous to use in food production since no hull
needs to be removed and thus a l l nutrients are retained. In
addition, using naked barley for malt ing has previously been
shown to produce malt with a composit ion and enzyme act ivit ies
comparable to that of normal malts (Bhatty, 1996).
Table 2.1 Typical chemical composit ion of barley grain
Component Percent Component Percent
Starch 63-65 Lipids 2-3
Sucrose 1-2 Albumins and globulins 3.5
Other sugars 1 Hordeins 3-4
Water soluble polysaccharides 1-1.5 Glutel ins 3-4
Alkali soluble polysaccharides
8-10 Nucleic acids 0.2-0.3
Cellulose 4-5 Minerals 2
Adapted from MacGregor and Fincher (1993)
In a study two cult ivars of hull-less barley, Scout (two-
rowed) and Tupper (six-rowed) were ut i l ized to prepare f lour and
similar ly ground f ine-pearled, and the pearled grain. These three
fract ions were used to evaluate physiochemical and funct ional
(bread making) propert ies. The fract ions contained 13.3-18.9%
protein, 1.1-2 .1% ash and 0.8-1.6% fiber; palmit ic (16:0) , oleic
(18 :1) , and l inoleic (18:2) were the major fat ty acids (Bhatty, 1986).
Kiryluk et al . , (2000) mil led barley to produce the end-
products: f ine and coarse-grained f lours, middlings and fine gr its .
These products differed in their average contents of β -glucan,
total dietary f iber , ash and protein. This product , with a weight
yield of 18.6%, contained 6.72% β -glucan, 25.12% total dietary
f iber, 2.19% ash, and 15.83% protein. All these values were at
about 50%, 72%, 55% and 24%, respect ively higher than in
dehulled barley.
Holtekjolen et a l . , (2006) observed a strong posit ive
correlat ion between the β -glucan and the amount of soluble non-
starch polysaccharides (NSP), as wel l as β -glucan and protein
contents. The analyzed hull- less and a typical amylose variety
seem suitable for human consumption where high soluble f iber
and nutrit ive contents are desirable. These variet ies contained
high contents of β -glucan, soluble NSP, protein and lower starch
content, and could therefore also be suitable for funct ional food
products aimed at health benefits and cancer prevention.
2.2 . Role of dietary fiber
Different countries and research groups have adopted
different definit ions for dietary f iber, which has led to
inconsistent results . Therefore a committee was formulated by the
American Associat ion of Cereal Chemists (AACC) to evaluate the
definit ions and methodologies used. An updated definit ion was
prepared by this committee in 2001 which concluded that “Dietary
f iber is the edible parts of plants or analogous carbohydrates that
are resistant to digest ion and absorption in the human small
intest ine with complete or part ial fermentat ion in the large
intest ine” (DeVries, 2001).
Dietary f iber includes polysaccharides, ol igosaccharides,
l ignin and associa ted plant substances and the data regarding the
beneficial effects of dietary f iber more than two decades have
been recorded. According to Schneeman (2001) dietary f iber
regulates the rate of nutr ient digest ion and absorption, serves as a
substrate for the microflora of the gut and promotes laxat ion. The
dietary f iber to foods is usually added for improving their
nutrit ional characterist ics (Brennan and Cleary, 2005). However ,
dietary f iber have both physiologica l and technological
propert ies, and its addit ion wil l also alter processing and
handling of foods as well as their texture, color, f lavor, and taste.
Many reports demonstrat ing the role and physiological
funct ioning of dietary f iber in human health and are involved in
reduction in cardiovascular diseases , colorectal cancer , and blood
cholesterol and glucose level .
Intake of total d ietary f iber, especial ly from cereal and grain
products (Bingham et al . , 2003 ; Jansen et a l . , 1999) can act as a
shield against diabetes (Maier e t a l . , 2000; Schulze et a l . , 2004). It
also helps in smooth bowl movement (Sanjoaquin et a l . , 2004) and
it is effect ive against const ipat ion (Dohnalek et al . , 2004). The
foods, rich in dietary f ibre provide low energy to the body and
interfere with absorption of harmful compounds. There dietary
f iber a lso showed to decrease the serum cholesterol levels (Brown
et al . , 1999).
Water-retention capacity is another important funct ion of
dietary fiber. According to their water solubil i ty dietary f iber can
be classif ied in to two group’s i .e . soluble and insoluble f ibers.
Soluble f ibers include mainly gums, pect in and mucilage while the
insoluble f ibers include cel lulose, hemicelluloses and lignin
(Izydorczyk et a l . , 2002) . Barley β -glucan, which is soluble dietary
f iber, can successfully be used in food system.
2.3 . β -glucan: Sources and occurrence
The term β -(1→3)-D-glucan includes a very large number of
polysaccharides from bacter ial, fungal and vegetable sources.
Their structures have a common backbone of β -(1→3) l inked
glucopyranosyl units but the polysaccharidic chain can be β -(1→6)
branched with glucose or integrate some β -(1→4) l inked
glucopyranosyl units in the main chain (Brennan and Cleary,
2005).
The barley crop is used for human consumption due to the
presence of i ts funct ional ingredients. Among all the cereals ,
barley and oat are famous for β -g lucan. Mixed-l inkage (1→3)-
(1→4)-β -D-glucan, or β -glucan, is the most abundant component
of the soluble dietary f iber in both oats and barley. I t is a l inear
and part ial ly water soluble polysaccharide that consists only of
glucose. I t is a soluble f iber component found predominantly in
other cereal crops. The (1→3)- (1→4)-β -D-glucan is cel l wall
polysaccharide of cereal endosperm and aleuronic cel ls .
Environmental condit ions seem to exert a significant effect on the
β -glucan content of the cereal grain (Aastrup, 1979).
β -glucan is one of the minor const i tuents in barley grains. I t is
primarily associated with genotype and is s ignificantly affected
by the environmental condit ions. There is a variat ion in barley β -
glucan content between different locat ions as documented by
Aman et al . , (1989). Zhang et al . , (2002) determined and extracted
β -glucan content of barley cult ivars col lected from various areas
of China, as wel l as from Canada and Australia by an enzymatic
method. For 164 cult ivars, originat ing from China β -glucan
content ranged from 2.98% (Sumei 21) to 8.62% (QB25), with a
mean of 4 .58%. Ragaee et al . (2001) a lso demonstrated that the
primary sources of β -glucan in the human diet are oats, barley,
rye and wheat . The levels of β -glucan in dehulled or naked oats
and most dehulled or naked barleys range mostly from about 3%
to 7% (Lee et al . , 1997), in rye about 2% and in wheat less than
0.5% (Beresford and Stone, 1983).
The structures of β -glucan in barley and oat are dif ferent
(Wood, 1994). Barley β -glucan was found to contain one quarter β -
(1→3) l inked units, whereas, oat β -glucan contained
approximately one third . The oat β -glucan structure, therefore,
contains more β -(1→3) l inkages than barley β -glucan (MacGregor
and Fincher, 1993). The oligosaccharide with DP3, i .e. 3-O-β -
cel lobiosyl-D-glucose, is the main product and DP4, i .e . 3-O-β -
cel lotriosyl-D-glucose, comes second. These two const itute over
90% of the total β -glucan content (Wood et a l . , 1994). For
structural dif ferences of β -glucan, of ten DP3:DP4 ratio is used as
indicator (Izydorczyk et al . , 1998a). According to many authors
this rat io is lower for oat than for barley β -glucan. Structural
differences have also been reported to exist between soluble and
insoluble β -glucans with the rat io DP3:DP4 being higher for
insoluble than for soluble β -glucans ( Izydorczyk et al . , 1998b).
2.4 . Extraction of β -glucan
Various techniques for the isolat ion of β–glucan have been
developed. β -glucan from barley and oat could be isolated by dry
mill ing and solvent extract ion (Wu et al . , 1994; Dawkins and
Nnanna, 1993; Saulnier et al . ,1994). Among both isolat ion
methods, about 89% β–glucan could be recovered by solvent
extract ion and only 31% by dry mil l ing and air classif icat ion (Wu
et al . , 1994) from barley and oat . However, 41-81% β–glucan on
dry matter basis could be extracted by using neutral or an alkaline
medium (Burkus and Temell i , 1998). Furthermore, more than 90%
extract ion could be achieved by hot water extract ion (Morgan e t
al . , 1998).
Bhatty (1995) compared different solvents for the extract ion
of β -glucan from one sample of hull- less barley bran and revealed
that sodium hydroxide was the most eff icient solvent for
extract ion. The extraction with sodium hydroxide removed 84% of
the β -g lucan compared to 72% by sodium carbonate solut ion and
only 61% by sequential extract ion with water at 40, 65, and 95°C.
The amount of β -g lucan is an important factor in considering
health effects. In the isolation processes, some β -glucan may be
lost . Thus, the total β -glucan content can not be determined from
the isolated β -glucan (Rimsten e t a l . , 2003). The most frequently
used method for β -glucan determination is i l lustrated by
Associat ion of Official Analyt ical Chemists (AOAC, 1995). This
method involves the dissolut ion of β -glucan in a buffer,
hydrolysis with the l ichenase enzyme to ol igosaccharides and
with β -glucanase to glucose. Glucose is then analysed
spectrophotometrical ly as a colored substance obtained with an
oxidase/peroxidase reagent (Lambo e t a l . , 2005).
Burkus and Temeil i (1998) have reported that extract ion
condit ions, such as pH and temperature, profoundly affect the
viscosity of solut ions prepared with β -glucan concentrates. I f a
higher concentrat ion of β -glucan is desired in a product , low
viscosity extracts may be ut i l ized (Burkus, 1996).
Carr (1990) explored an improved method for the
determination of (1→3)-(1→4)-β -D-glucan in cereals and their
products. The method includes refluxing of 80% (v/v) ethanol to
remove sugars and inact ivate of enzymes prior to extract ion with
water at 100ºC for soluble β -glucan determination. For several
different food products, soluble β -glucan content ranged from
0.49 to 3.90%, whereas total β -glucan content ranged from 0.58 to
8.86% (dry weight basis) . The dietary f iber ranged from 4.8 to
22.0% for the products.
Extract ion condit ions also determine the properties of
extracted β -glucan. Wood et al . , (1977) extracted the β -glucan gum
pellets through alkali extract ion method from oats (Avena sat iva
L.) . The researchers found that various condit ions such as
temperature, pH, and ionic strength of the extraction media
affected the β -glucan yields. β–glucan could also be extracted by
using dist i l led water and 4% sodium hydroxide. All treatments
differ in their yield and physiochemical propert ies. Extracted
condit ions have a great bearing on viscosity propert ies of β -
glucan; excessive boiling during extract ion resul ted in low
viscosity β -glucan. Stable barley β -glucan gum with high viscosity
can be obtained using suitable combination with high pH
(Johansson e t al . , 2000) . Recently, another method was developed
by Izydorczyk et al . , (1998) for the extract ion of β -glucan through
sequential extract ion with water Ba(OH)2, Ba(OH)2/H2 O, and
NaOH. In this method each barley sample was extracted 2–3 t imes
and the isolated material was combined.
The β–glucan extract ion methods for pilot plant levels have
been developed that includes refluxing with 75% ethanol for four
hours prior to extract ion-deact ivated glucan. The pilot plant
extracted gum has less viscosity than bench gum; this is due to
high shear rates, enzyme act ivity of fungi and bacteria in pilot
plant condit ions (Wood et al . , 1989). The foods containing β–
glucan needs viscosity stabil ity for increased shel f l i fe . In another
study, i t is found that i f 1N sodium hydroxide is used for β–
glucan extraction from barley and oat , i t affect β–glucan act ivity
(Bhatty, 1995). The enzymes (glucanase) present naturally or
produce from microorganisms and it is invest igated that
enzymatic hydrolysis create problem during production and food
application. Scient ists noticed h igher act ivity of endo (1→3), β -D-
glucanase than endo (1→3) (1→4) β -D-glucanase (Brunswick e t al . ,
1987). Similarly, steaming and kilning inact ivate l ipases of barley,
microbial enzyme are more heat stable than the endogenous
glucanases (Balance and Meredith, 1976; Wood e t al . , 1989).
Similarly, a method of pure β -glucan extraction has been
provided by Westerlund et al . (1993) and this method involves
defatt ing with propan-2-ol ( isopropanol, IPA) and petroleum
ether, dissolut ion in water at 96 °C and hydrolysis of starch with
heat-resistant α-amylase. The polysaccharides are precipitated
with 60% ethanol at 4 °C and the precipitate is dissolved in water.
The solut ion is treated with 30% (NH 4 )2SO4 , which specif ical ly
precipitates β -glucan but leaves arabinoxylans in solution. The
precipitate is dissolved in water and dialyzed against water at
room temperature.
2.5 . Health benefits of β -glucan
Barley grain bas been shown to be an excel lent source of
both soluble and insoluble f iber and according to diet i t ians and
health professionals, i t should be extensively used in diets to
improve health (Oscarsson e t a l . , 1996). During the last 10 years
studies have identif ied a low glycemic-index (GI) diet as
beneficial in relat ion to the insulin-resistance syndrome. Several
semi-long-term dietary interventions are available for healthy
subjects and for subjects with metabolic diseases. With a few
exceptions, these studies have shown that a low-GI diet not only
improves certain metabolic consequences of insulin resistance, but
also reduces insul in resistance per se (Del Prato et al . , 1994). In
addition to improvements in glucose and l ipid metabolism
(Jenkins et al . , 1987; Brand et al . , 1991; Jarvi et a l . , 1999) there are
indicat ions of improvements in the f ibrinolyt ic act ivity (Järvi et
a l . , 1999), suggest ing a benefic ial role in diabetes and
cardiovascular disease. I t has been est imated that a 3 .85 unit
reduction in GI can be perceived per gram of β -glucan f iber in a
50 g carbohydrate portion of food. The viscosity of the f iber
relates posit ively to the degree of f lat tening of postprandial
glycemia (Wood et a l . , 1994; Jenkins et a l . , 1978).
The potential physiological mechanisms behind the eff icacy
of β -glucan are suggested to be i ts abil ity to retard the absorption
rate of food in the intest ine due to increased viscosity, in this way
balancing the post-prandial glucose and insul in response (Wursch
and Pi-Sunyer, 1997; Wood et al . , 2000). In addit ion, some
invest igators (Gal laher and Hassel , 1995; Ja l i l i et al . , 2000) has
reported an increased viscosity in the small intest ine, which may
interferes with cholesterol absorption or re-absorption, in this
way af fect ing the cholesterol balance and synthesis in the body.
Therefore i t would be interest ing to invest igate what kind of
ef fect could be achieved with general information about the
dietary f iber content (Stone and Clark, 1992).
Another physiological aspect with reference to β -glucan was
experienced in intest inal t ract that i t s low down glucose
absorption and, therefore, regulate blood glucose (Wood et a l . ,
1990; Wood et a l . , 1994). The viscous nature of β -glucan physically
slows glucose absorption in the gut . This property may be useful
in the formulat ion of products target ing management of diabetes.
The mechanism by which β -glucan lowers blood glucose and
cholesterol levels may be related to i ts viscosity, bi le salt binding
capacity or ferment abi l i ty (Davidson and McDonald, 1998;
Marlett et al . , 1994). The enrichment technique and water
extract ion/freeze drying technique could enable the use of barley
as a source of a high-value f iber for reducing the glycemic index
of tradit ional wheat-based foods such as bread, without affect ing
their sensory character istics . (Cavallero, 2002)
β -glucan incorporated functional food tends to reduce
glycemic indices while maintaining palatabil i ty (Jenkins et a l . ,
2002). β -glucan containing food bars have an intermediate
glycemic index of 78 (Foster-Powell and Miller , 1994). Enrichment
with additional β -glucan is required in order to produce a low
glycemic index barley product , (Tappy et al . , 1996) which could
also have an increased hypocholesterolemic effect (McIntosh et a l . ,
1991).
Dongowski et a l . , (2002) reported that diets containing more
solub le macromolecular dietary f ibers such as β -glucan af fected
the excret ion of b i le acids and neutral sterols the most , whereas
the fermentat ion of dietary fiber , including resistant starch,
influenced the steroids in feces. I t has been hypothesized that ,
upon ingest ion, β -glucan increases small intest inal v iscosity due
to i ts lower molecular weight and its tendency to form viscous
gummy solut ions, result ing in reduced bile acid and cholesterol or
tr iglyceride absorption thus lowering plasma cholesterol , as wel l
as altering digest ive enzyme act ivity.
More research is in progress to determine the effect of β -
glucan and phytosterols into low-fat spreads and non-fat
phytosterol formulations (Moreau e t a l . , 2002). The cholesterol -
lowering potential of β -glucan and phytosterols may thus depend
upon previous dispersion into a fat matrix and on the physical
nature of the food. I t is reported that these compounds have a
capacity to reduce plasma cholesterol concentrations when
consumed in dif ferent food matr ices, but their effect iveness in
non-fat or low-fat beverages has not been established (Jones et
a l . , 2003). Two mechanisms for serum cholesterol level have been
elucidated in the scientif ic l i terature one deals with the viscous
nature of β -glucan provides a physical barrier that s lows down or
inhibits the absorption of cholesterol and other lipid const ituents
and second mechanism is about binding of the bile acids in the
gut . The unabsorbed and bound components then proceed to the
large intest ine and are excreted from the body. Some of the β -
glucan that reaches the colon wil l also undergo fermentation by
colonic microorganisms (Wood and Beer, 1998; Casterl ine et a l . ,
1997; Bel l et al . , 1999). Short chain fat ty acids are produced as a
result of fermentat ion of β -glucan in large intest ine.
β -glucan have cholesterol lowering act ion in human body.
The cholesterol lowering mechanism involved the suppression of
intest inal cholesterol absorption while partial ly suppressing
cholesterol biosynthesis (Jones e t a l . , 2000; Plat and Mensick, 2001)
only a small part of these are absorbed through intest inal micelle
into blood circula t ion, phytosterol solubil i ty and incorporat ion
into intest inal micelles is found an important aspect of
phytosterol cholesterol lowering eff icacy. Most recent studies
conducted to examine the l ipid- lowering potential of β -glucan
incorporated them into a fat matrix: margarine, butter, or
dressing. Results from these tria ls have shown that β -glucan
consumption decreases total cholesterol and LDL- cholesterol
concentrat ions by 3.4% to 11.6% for total cholesterol and 5.4% to
15.5% for LDL cholesterol (Jones et al . , 2000; Hall ikainen et al . ,
2000; Mussner et al . , 2002). Oat bran is r ich in β -glucan f iber and
has been shown to lower cholesterol (Anderson et al . , 1990). This
is believed and found that barley and oat lowers the blood
cholesterol and attenuates postprandial glucose response due to
soluble dietary f iber cal led (1→3) (1→4)-β -D-glucan also referred
to as β -glucan (Ripsin et al . , 1992; Tappy et al . , 1996; Drzikova,
2005). Oat bran reduced total serum cholesterol in
hypercholesterolemic subjects by as much as 23% with no change
in high density l ipoprotein (HDL) cholesterol. Since oat bran was
enriched in β -glucan (Wood, 1986; Wood et al . , 1989), the authors
reported an inverse correlat ion between serum cholesterol levels
and β -glucan intake. Barley and oats are a rich source of the
soluble f ibre β -glucan, which has been shown to significantly
lower LDL-cholesterol ( Joseph et a l . , 2007).
Oat bran providing 7 .3 g β -glucan in a breakfast cereal or 6.2
g in a bar gave significantly lower postprandial glucose responses
in NIDDM subjects than an oat bran breakfast cereal providing 3 .7
g, and it was calculated that the glycemic index was lowered 4
units for every gram of β -glucan (Jenkins et a l . , 2002).
In a study different breads were made, one from hul l-less
barley f lour and the other from two (1→3, 1→4)-β -glucan enriched
fract ions. The remaining two from a sieved fract ion (SF) and a
water-extracted fract ion (WF) were produced and evaluated for
sensory evaluation. For eff icacy study eight adults’ subjects were
fed test meals of each of the four breads, containing the same
amount (50 g) of available carbohydrate, and glycemic indices
calculated from f inger-prick capil lary blood samples. A l inear
decrease in glycemic index was found for increasing (1→3) (1→4)-
β -glucan content . This research confirms the ef fect iveness of
viscous (1→3) (1→4)-β -glucan in reducing postprandial blood
glucose levels; even in foods with a high glycemic index
(Cavallero et al . , 2002).
The abil i ty to detect a significant ef fect on glycemic
response related to the dose of β -glucan. In a study of the effect of
an oat bran highly enriched in β -glucan (15% dwb) incorporated
into an extruded breakfast cereal , subjects with non-insulin-
dependent diabetes mell i tus consumed meals with 4, 6 , and 8.6 g
of β -glucan All 3 breakfasts significantly decreased the peak and
the average increases in glucose and insulin compared to a
control . There was a significant relat ionship between plasma
glucose peak and area under the glucose curve and the amount of
β -glucan in the cereals (Tappy et a l . , 1996). Wood et al . , (1990)
showed that both oat gum and guar gum significantly decreased
the postprandial glucose rise. Scientists conducted a study and
showed that whole meal , bran, and flour from three barley
genotypes, which contained graded levels of soluble f iber, were
compared with similar commercial f ract ions of oats for their effect
on cholesterol , t r iglycerides, high-density l ipoprotein (HDL)
cholesterol and l iver cholesterol ( test model, using
hypercholesterolemic rats) . Whole meals of the three barley
genotypes contained 3.0 , 5.2, or 6.8% soluble f iber; oatmeal
contained 3.0%. In meal-fed rats, bar ley genotypes did not show a
favorable blood or liver l ipid response compared with oats.
However, in bran- and flour-fed rats, the data showed that
barley exerted a profound blood and l iver cholesterol- lowering
ef fect compared with oat bran or flour (blood triglyceride levels
were minimally affected). Blood HDL-cholesterol levels were
appreciably elevated in rats fed barley bran or f lour compared
with oat bran or f lour. These results suggested that barley and its
major fractions (bran and flour) may evoke dif ferent lipidemic
responses and that barley bran and flour have a more favorable
ef fect on blood l ipids than do oat bran and flour (Ranhotra et a l . ,
1991).
Wallace et al . , (1997) developed product containing high-
fiber, high-carbohydrate diets , including foods with low glycemic
index, have been associated with prevention and treatment of
diseases such as coronary heart disease and diabetes. β -glucan, a
soluble, v iscous polymer found in oat and barley endosperm cel l
wall , was incorporated into pasta test meals. Five fasted adult
subjects were fed test meals of barley and durum wheat blend
pasta containing 100 g of available carbohydrate, 30 g of total
dietary f iber (TDF) and 12 g of β -glucan, or a l l durum wheat pasta
containing the same amount of available carbohydrate, 5 g of TDF,
and negligible β -glucan. The β -glucan and durum wheat pasta
resulted in a lower glycemic response as measured by average
total area and maximum increment of the blood glucose curves.
Lower insulin response to the β -glucan and durum wheat pasta
was also indicated by lower average area and increment
characterist ics of the insulin curves . Barley, β -g lucan may be an
economical and palatable ingredient for processed food products
formulated to modify glycemic and insulin response.
Lia et al . , (1995) studied the effect of β -glucan on the
excretion of bi le acids using breads baked with oat bran, oat bran
with β -glucanase, barley or wheat in the diet of i leostomy
subjects . They showed that the excret ion of bi le acids was 53%
higher with the oat bran bread than with the bread containing oat
bran and β -glucanase, and also significantly higher than with
barley and wheat bread. The excretion of cholesterol was higher
for barley bread than for wheat or oat bran-β -glucanase bread. In
one of the few studies that have reported MW values, a dr ink
containing 5 g β -glucan of MW 70,000 extracted from oat bran
significantly lowered postprandial glucose and insulin levels
relat ive to a rice drink control , whereas a similar drink containing
barley β -glucan of MW 40,000 was without signif icant ef fect
(Biorklund et a l . , 2005).
A study was further conducted to est imate the glucose,
insulin, and glucagon responses after consumption of high-soluble
β -glucan compounds from oats and barley. The study includes 11
men and 11 women, non diabet ics between 35-57 years old
subjects . Different tests (b lood and urine) performed to analyze
the glucose responses. The preliminary results showed the
significant decrease in oats , barley, and both extracts than glucose
solut ion. High-soluble barley f iber is more effect ive than standard
oats. Oat and barley carbohydrate-based fat substitutes can
provide a useful addition to control plasma glucose responses
(Hallfrisch et a l . , 2003).
Invest igat ions are further continued to f ind the cholesterol-
lowering act ivit ies of oats and barley. In this study, the anti
atherogenic propert ies of β -glucan concentrates from oats and
barley were evaluated in Syrian golden F1 B hamsters by
consuming a semi puri fied hypercholesterolemic diet (HCD)
containing cholesterol (0.15 g/100 g) , hydrogenated coconut oi l
(20 g/100 g) and cel lulose (15 g/100 g) .The experimental diet HCD
formulated with different levels of β -glucan (2, 4, or 8 g/100 g)
from oat and barley instead of cel lulose. In agreement with
previously proposed mechanisms, total fecal neutral sterol
concentrat ions were significantly increased in hamsters
consuming 8 g/100 g barley or oat β -glucan. Aort ic cholesterol
ester concentrat ions were significantly reduced in hamsters fed 8
g/100 g β -glucan from barley or oats. From this observational
study found that the cholesterol- lowering potency of β -glucan is
approximately identical whether i ts origin was oats or barley
(Delaney e t al . , 2003).
2.6 . Functional properties of β -glucan
Other than nutrit ional benefits obta ined from β –glucan, i t
also have valuable funct ional propert ies such as thickening,
stabil izing, emulsif icat ion, and gelat ion, which make β -glucan
suitable for incorporat ion in soups, sauces, beverages and other
food products (Dawkins and Nnanna, 1993; Burkus and Temel l i ,
1999). Such funct ional propert ies are very important for new food
applications. However, proper knowledge on thermodynamic
propert ies of β–glucan in a food system with other food
components is necessary to exploit full benefits (Burkus, 1996).
Gelation is associated with cross l inking of long chain of
polymer to form three dimensional continuous networks, this
structure traps and immobil izes the l iquid and become thick
enough to f low under pressure (Glicksman, 1982). β–glucan is a
long chain of glucose units, counts for 3-7% of total grain weight
which make it more viscous. Both amylose and β–glucan are
straight chain of glucose. I t has been found that amylose chains
align themselves and form gel , while β–glucan form gel through
interrupted regions of β -(1→3) l inkages (Buliga et al . , 1986). Due
to presence of glucose bond between (1→3) (1→4) l inkages that
make barley β–glucan a soluble f iber , β -glucan provides excellent
viscosity forming properties and used as thickening agents in
different food applicat ions, e.g. salad dressings, sauces and ice
creams (Wood, 1986). Thus addit ion of barley β -glucan into foods
not only to give better nutr it ional enhancement but also help to
improve quality parameters such as processing behavior and
shelf- l i fe or stabil i ty ( Klamczynski and Czuchajowska, 1999).
Thammakit i et al . , (2004) determined and evaluated that β -
glucans, obtained from spent brewers yeast , and its potential food
applications. The objective of the study was to evaluate the effect
of homogenizat ion on the rheological properties, chemical
composit ion and funct ional propert ies of β -glucan. In case of
homogenized cel l walls higher β -glucan content and apparent
viscosity has been observed than those which had not been
homogenized due to the breakup of cel l walls. This extracted β -
glucans has shown higher apparent v iscosity, water-holding
capacity and emulsion stabil iz ing capacity, but very s imilar oi l -
binding capacity when compared with commercial β -glucans from
bakers yeast .
Dawkins and Nnanna (1995) reported that β -glucan viscosity
and stabil ity showed diverse behavior when maintained di fferent
pH-temperature-t ime combinations during processing and
decrease stabil i ty of food systems such as salad dressings i f β -
glucan is used as a stabil izer. The presence of other food
ingredients can affect propert ies of hydrocolloids. Sweeteners
alter the solut ion properties such as sucrose, in low to mild
concentrat ions increased viscosity of oat β -glucan, while higher
concentrat ions lowered viscosity. S imilarly, Beer et a l . , (1997) has
substantiated that processing may affect solubil i ty of β -glucan
and decrease the molecular weight of β -glucan. I t is obvious that
when β -glucan is used in bread making significant
depolymerizat ion of l inear bond of this polysaccharide was
caused (Andersson et al . , 2004).
Lyly et al . , (2004) conducted a research study on two
different β -glucan sources and found that the sensory
characterist ics of soups prepared from barley β -glucan were
different compared to oat β -glucans. Freezing had no remarkable
ef fect on the molecular weight of β -glucan or on the sensory
attribute of the soups. The researchers visualized that barley β -
glucan addit ion resulted in alterat ions of a food's funct ional
propert ies, such as viscosity. More stable foams and emulsions
were obtained with incorporation barley β -glucan than oat β -
glucan. Morgan e t al . , (1998) also observed that β–glucan from
barley makes soft gel on cooling at more than 0 .5% concentrat ions.
β–glucan stabil i ty is dependent on t ime, temperature and pH
values and these factors a ffects both viscosity and stabil i ty when
used in foods as s tabil izers (Burkus and Temell i , 1999). There are
reports by researchers showing that viscosity is a funct ion of
molecular weight . I t is important to determine precise molecular
weight to estimate β–glucan characterist ics for potential
applications into food products. Among cereals, barley and oat
showing high concentrat ions of β –glucan , this unique property
differentiate them from others (Burkus, 1996). I t is wel l known
that barley and oat β -glucan is very similar in structure. As for as
viscosity is concerned it has been observed that oat β - glucan has
high viscosity than barley due to long molecular chains (Beer et
al . , 1997). Temperature is responsible for changes in viscosity and
according to observations found that oat β –glucan gum viscosity
rises from 25-370 C and start decreases from 61 0C and maximum
reduces at 1000 C when compare with control treatment at 250 C
(Dawkins and Nnanna, 1995). Furtehrmore, barley β–glucan
imparts a smooth mouth feel to beverage products, while also
making the beverage an excellent source of soluble dietary f iber.
In beverage formulat ions, i t can provide similar funct ionality l ike
other thickeners. β -glucan gums have shown such types of results
that are comparable with other thickners such as alginates, pect in,
xanthan, and carboxymethylcellulose (Giese, 1992).
2.7 . Utilization of β -glucan in food products
Food industry has a major focus on the production of foods
containing health-enhancing components that wi l l improve
consumer health beyond meeting basic nutrit ional requirements
(Sloan, 1999). Currently funct ional and nutraceutical ingredients
are used to exploit their health benefits and it has been found that
beverages provide excellent medium for their addit ion (Kuhn,
1995). Barley is sui table for a range of food applicat ions and it can
be processed into a number of palatable and nutri t ious food
products. As other polysaccharides, β -(1→3)-D-glucans have
found a very large range of possible applicat ions in various
industries and especially in foods, cosmetic , agronomy,
therapeutic , and other. In food industry, bes ide typical
applications of polysaccharides as thickening agent and
stabil izers, β -(1→3)-D-glucans have an increasing interest in the
areas of edible f i lm and wide applicat ion into feed for domestic
animals and low calorie food as chemical addit ives are not famous
among the consumers. Barley gives rise poor baking qual ity and
also not having good taste and appearance aspects which have
l imited its use in human foods. However, in current years there
has been an increasing research interest for the exploitat ion of
barley in a wide range of food applicat ions (Bhatty, 1999).
During the last few years funct ional drinks sector has been
strong and expected to continue Growth in future (Potter, 2001;
Sloan, 2002). Industry analyst predict and saying continuous
growth and latest research has focused on the use of soluble
dietary f ibre, and in part icular cerea l β -glucans, as stabil izers in
the manufacture of low-fat products such as salad dressings
(Kontogiorgos, 2004), ice creams, yoghurts (Brennan, 2002), cheese
and many other food products. The use of β -glucans preparat ion,
to part ial ly substitute vegetable oi l in the formulat ion and is
found that give us many advantages in the food system. Barley β -
glucan, is a compound which as at tract ive thickening propert ies
and does not reveal deter iorat ive changes during processing and
storage periods. It gives rise good thick solut ion propert ies when
added into water. It is suggested that β -glucan gum can be used
as thickener in dif ferent food applicat ion i .e. in ice cream, sauces
and salad dressing (Carr et al . , 2002) Furthermore no bad effect on
sensory propert ies was reported. There is an est imate and
predict ions by industry analyst that funct ional drink wil l make a
good share in food sect ion. (Sloan, 2002).
Erkan et al . , (2005) produced tarhana (fermented cereal
product) samples from hulless and hulled barley with relat ively
high β -glucans content . Chemical and sensory properties of the
tarhana samples were examined and evaluated with the
tradit ional wheat tarhana. During fermentat ion, some of the β -
glucans may be destroyed; however the results indicated that
barley f lours can be ut i l ized to produce tarhana with relat ively
high β -g lucans content . Effect of tarhana product ion on the
electrophoret ic properties of proteins was est imated in this study
by using SDS PAGE. Relative band intensit ies of tarhana samples
were generally less intense than those of respect ive f lour samples
perhaps due to the hydrolysis of proteins during fermentation.
However, the overall sensory attributes showed that ut i l ization of
barley flours in tarhana formulat ion resulted in acceptable soup
propert ies in terms of most of the sensory propert ies.
Another product where Barley has been effect ively
incorporated by (Sidhu et al . , 1990) and made single layer f lat
breads including chapatis and Turkish bazlama bread by Basman
& Koksel , (1999). A further study conducted by Berglund et a l . ,
(1992) and he has successfully used hull -less barley f lour in
chemically leavened products such as biscuits, pancakes, muffins
and cookies. Such yeast- leavened bread made with hull-less
barley f lour is a lso being a good dietary source of (1→3) (1→4) β -
glucan. Traditionally barley is not often used in bread products
because i t is defic ient in g luten and has poor sensory qualit ies .
Izydorczyk et al . , (2001) showed that barley might replace up to
20% of wheat f lour without causing too much disturbance to the
overall dough qual ity.
Similarly, Morin e t a l . , (2002) established that addit ion of
barley β -glucan gum (76.2% purity) into reduced-fat breakfast
sausages to such an extant that i t provides 0 .3–0.7% β -glucan in
the manufactured goods gave better water binding and at a level
of 0 .3% having no significant ef fects on product texture or f lavor.
A study performed by Volikakis et al . , (2004) in which he
used elevated level of β -glucan in cheese. A commercial
concentrate of oat β -glucan (22.2% β -glucan content) has been also
incorporated into low-fat white-br ined cheese from bovine milk
(70% fat reduction) at two levels, 0 .7% and 1.4% (w/w). This
product showed in an increased yield, greater proteolysis and
higher levels of short chain fat ty acids ( lactic , acet ic , and butyric)
as well as with improved texture compared to i ts low-fat (β -
glucan-free) counterpart . However, the product made with the
high level of β-glucan has shown significantly inferior impression
scores for colour, f lavour than those of a typical white-brined
cheese product.
2.8 . Physico-chemical characteristics of beverage
Among funct ional foods beverages have excellent
opportunities for the incorporat ion of nutraceutical ingredients.
Giese (1992) stated that the new formulations of beverages are
rapidly changing. The market shelves are full of different
beverages with not only soda pop, juices and dairy beverages.
There is huge number of food products taken as beverages such as
iced teas and coffees, sports drinks, herbal teas, f rozen carbonated
beverages, mint blends, vegetable juices, smoothies. Soft drinks
have tradit ionally remarkable share in the market . However, in
current years consumers have not been choice for tradit ional
drinks but also have more exotic beverages such as the, teas iced
coffees, isotonic or sports drinks and non-carbonated beverages
and ready-to-drink iced herbal teas are also gaining popularity
(Swientek, 1998).
Beverages not only provide taste and refreshment
sat isfact ion, but can also offer a ready and unique delivery system
for protein, v itamins, minerals and other food ingredients such as
dietary f iber. A major challenge to develop a nutraceutical
beverage is to preserve i ts nutrients and to make it taste good.
Another challenge involves the processing of these beverages with
minimum losses of f lavor, vitamins, and color. Barley β -glucan is
being used frequently in cereal products. According to FDA new
types of foods containing β -glucan are need to promote in which
3g of β -glucan/day should be used, this is the amount defined
amount to get the potential hea lth ef fects. Beverages showed
sui table category for new product development containing β -
glucan as funct ional ingredient .
FDA has recommended consumption of 3 g β -glucan per day
to achieve such health benefits . This claim was amended later on
and includes oat extracts containing up to 10% β–glucan (FDA,
2002). Some studies showed that consumers want to pay more for
foods having funct ional benefits ( Jonas and Beckmann, 1998).
Processing condit ion for extract ion of β -glucan is important
because i t may affect physiological , molecular weight and
solubil i ty of barley β–glucan (Beer et al . , 1997) and therefore has
influence on its physiological eff icacy and products development.
High molecular weight β -glucan is part icularly sensitive to
processing. Freezing has not been found to af fect the molecular
weight of β –glucan (Suortt i et al . , 2000; Kerckhoffs e t al . , 2003)
but i t decreases the solubil i ty of β –glucan (Beer et al . , 1997). On
the other hand, heat ing makes β -glucan more soluble (Bhatty,
1992; Jaskari et al . , 1995) and enhances i ts physiological ef f icacy.
The beverage prepared at high temperature had a sl ightly
higher apparent viscosity than the pulse electric f ield (PEF)
treated beverage and developed sedimentation problem in the
container during storage. The PEF processed beverage maintained
its natural orange juice l ike color was better than the heat treated
beverage, which developed a sl ightly whit ish color. However, the
PEF treated product was less microbiologically stable at
refrigerat ion temperature compared with the heat treated product
which was stable for more than 12 month (Sharma e t al . , 1998).
Temel l i e t a l . , (2004) prepared an orange-flavored barley β -
glucan beverage with different β -glucan levels and compared with
same level pect in beverage and analyzed for di fferent sensory
parameters and the trained panelists found peely and fruity
orange aroma and sweetness intensity to be similar for al l
beverages tested. Beverage sourness intensity di ffered among
beverages. Panel ists evaluated beverages containing 0.3%
hydrocolloid as similar, whereas beverages with 0.5 and 0.7% β -
glucan were more viscous than those with pect in at these levels .
Acceptabil i ty of beverages was similar according to the consumer
panel . During the f irst week of storage Colorimeter values of
beverages decreased, mostly stabil izing thereafter. With an
increase in concentrat ion, β -glucan beverages became l ighter in
color and cloudier, but these at tributes for pect in beverages were
not affected. During the f irst three weeks of storage β -glucan
beverages exhibited cloud loss.
Barley β -glucan has revealed beneficial nutrit ional and
physical funct ionality characterist ics that are required for
beverage making (Temell i et al . , 2004). β -glucan can be used in
combination with whey protein isolate (WPI) for funct ional
beverage development. This beverage has shown good results for
qual ity, overall acceptabi l i ty and remained acceptable for 8-week
storage. Non-significant results for other quality parameters such
as sweetness, sourness and flavor intensity was observed. Many
researchers have attempted the use of β–glucan in beverage
(Holsinger et al . , 1974; Pendergast , 1985). Whey protein in
combination with β–glucan is successfully using in other food
systems due to nutrit ional and functional propert ies. Different
diseases can be prevented with the help of barley β–glucan and
whey protein isolates when used in foods (Temell i et al . , 2004). β–
glucan is extracted from oats and oat porridge is made, after
consumption it was demonstrated that product has reduce
postprandial blood glucose level (Wood et al . , 1990; Wood et al . ,
1994). These developments led top the approval of a health claim
for oats by the Food and Drug Administrat ion (FDA) in the United
States, indicat ing that oatmeal , whole oats, and oat products
containing 0.75 g of β -glucan per serving may reduce the risk of
heart disease FDA, 1999). Kulkarni et a l . , 2008 made a barley tea-
l ike extract that is a popular summer drink in Japan and explained
the effects of various temperatures between 150 0 C and 2800 C
during sub crit ical water extract ion of barley. Each barley extract
was carried out for, ant ioxidative activ ity, amount of residual
matter and sensory propert ies that were found at 2050 C. I t was
found that 5-Hydroxymethyl-2-furaldehyde is the most important
antioxidative component of the extract at 205oC.
M any re sea rche rs w o rke d on so f t dr i nks and b e ve rages a nd c onduc te d
di f f e re nt a na l ysi s on qu al i ty p ara mete rs a s D’ Heu reu x-C al ix a nd Ba dr i e
(2 005) ob se rve d the color and microbial aspect of puree during
storage. At pH 2.3 an intense red color is achieved. There were no
significant changes observed for physicochemical parameters
except consistency and hue angle for color. The puree contained
the total soluble solids in the range of 41 .0–43.5°Brix and pH was
2.62. There are reports for the development of new formulat ions
and then undergo sensory evaluation process to test their
consumer acceptance. Maestri et a l . , 2000 added the ethylene
diamine tetra acet ic acid (EDTA) in soy bean and proposed a new
method to at tain a soybean with improved flavor characterist ics
and found that a water/bean rat io of 4 .5:1 has given better
results and provided the best protein (4 .22 g 100 ml- 1) and total
solids (8.80 g 100 ml- 1 ) contents. The soybean was evaluated for
pH, viscosity and density, as well as for protein, compare with
soybean beverage.
In the same way Singh and Nath (2004) testify di fferent
composit ions for beverage and used denatured whey protein
concentrate (WPC) in the presence of pect in and carboxy
methylcellulose (CMC). The formulat ion of beverage was 25% bael
fruit pulp, 16°Brix , and pH 3.9 and was fort ified with 1.75, 2.75
and 3 .75% level of WPC-polysaccharide complex. Among all
combinations, he rated foodstuffs with 1 .75% protein level of
pect in-WPC complex and 1 .75 and 2.75% protein level of CMC-
WPC complex. Moreover, 1.75% whey protein level of CMC-WPC
complex was assigned maximum scores for al l sensory aspects .
Lakshmi et a l . , (2005) optimized the condit ions for beverage
formulat ions. They used mixture of enzymes varying pH,
temperature etc. under controlled conditions. The carbonated
beverage having 12.5% juice, 16°B total soluble solids (TSS) and
0.4% acidity was suitable for storage. During storage, beverage
tends to retain i ts quality at tributes l ike taste and flavor up to 2
months. Refrigerat ion of the produce could be imperat ive in
enhancing the shelf l i fe of the produce. Refrigeration at colder
temperatures also favors the retention of act ive components as
Prat i et al . , 2004 revealed ascorbic acid content maintained their
level during storage, with a loss of only 20% in relat ion to the
concentrat ion added.
Different combinations used by Suh et al . , 2003 including
barley sprouting and sweet potato. The mixture of barley sprouts
and sweet potato was ut i l ized in the ratio (1:1) to increase the
industrial applicat ions of sweet potato and rice beverage. I t was
also established that the heat stabil i ty of amylase in sweet potato
is higher than that in barley. Reducing sugar content in the
mixture of barley sprouts and sweet potato was higher than in
either barley sprouts or sweet potato alone. Sahu e t al . , 2005 used
lemon grass in beverage formulations and observed that fresh
beverage having 15.2°B total soluble solids (TSS), pH 4.35, 23 .29%
total sugars, 4.53% reducing sugars, 0.19% acidity and 1 .5% lemon
grass dist i l late obtained the average sensory score of 8.58, which
was highest among the other beverages prepared with different
concentrat ions of lemon grass dist i l late. At small scale barley and
pect in beverage can be produce by adding water in s team jacket
kettle then mix β–glucan or pect in and boil for one minute,
sucrose is premix in water. This whole mixture is cool down to 70
oC. Add High fructose corn syrup and orange f lavour, then
homogenize at 2000 psi , shift mixture into steam kett le and add
ascorbic acid, c i tr ic acid and β–glucan. The mixture is Pasteurize
at 90oC for hal f minute. At the end bott les are hot f i l led and
placed at refr igerator temperature (Temell i e t al . , 2004).
Barley (Hordeum vulgare L.) is mainly used for brewing in
developed countries and as animal feed in less developed
countries. However barley has great potential due to soluble f iber
content for human consumption and industrial uses. The cel l walls
of barley grain contain more β–glucan as compared to aleurone
cel l walls . The addit ion of β–glucan in water wil l enhance the
viscosity and used as a thickening agent in beverages. The act ion
of this soluble dietary f ibre is just l ike a typical visco-elastic
polysaccharide l ike pectin, guar gum, carboxymethylcellulose
(CMC) and xanthan, when used in different food products. In
recent era the applicat ion of β–glucan in food matrix play a key
role as a funct ional dietary f ibre.
The development of funct ional beverages by incorporat ing
β–glucan, show excellent results as a nutraceutical ingredients.
Barley β–glucan gum is stable in low pH condit ions and in
refrigerated storage. The purity of β–glucan depends upon
extract ion and isolat ion method used. The unpurified samples of
β–glucan causes problem when added in to the food systems. The
increasing trend of viscosity due to β–glucan is considered to be
an important factor in lowering the postprandial blood glucose
levels and cholesterol .
Dist inct ive research is mandatory to est imate the ef fect of
various process parameters on the rheological character istics and
molecular weight profi les of β–glucan extracts and determine how
processing af fects the eff icacy of incorporated β–glucan. Such
research would widen our perceptive to know, how β–glucan may
affect the nutrit ional propert ies of foods by altering their texture
structure, and viscosity.
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