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.