#573_MARCONI_bozza


	

Ital. J. Food Sci., vol 29, 2017 - 112 

PAPER 
 
 
 
 
 

ARABINOXYLANS AND β-GLUCANS ASSESSMENT 
IN CEREALS 

 
 
 

M. C. MESSIA, T. CANDIGLIOTA, E. DE ARCANGELIS and E. MARCONI* 
Dipartimento Agricoltura, Ambiente e Alimenti, Università degli Studi del Molise, Via De Sanctis, 86100 

Campobasso, Italy 
*Corresponding author. Tel.: +39 0874404616; fax: +39 0874404855 

E-mail address: marconi@unimol.it 
 
 
 
 
 
 

ABSTRACT 
 
Arabinoxylans (AX) and β-glucans are the major source of soluble dietary fibre in cereals 
and have a significant role as functional/bioactive ingredients implicated in lowering 
plasma cholesterol, postprandial blood glucose and improving lipid metabolism. In this 
work, the variation in the content and solubility of AX and β-glucans in different cereal 
species and varieties were studied. Different methods (phloroglucinol, orcinol-HCl, 
HPAEC-PAD) for AX analysis were tested. The results confirmed the variability in 
contents of both polymers (AX and β-glucans) in cereal species and varieties as well as 
providing additional information useful for their characterization. 
 
 
 
 

 
Keywords: Arabinoxylans, barley, β-glucans, emmer, spelt, wheat 

 



	

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1. INTRODUCTION 
 
The most common source of dietary fibre are the outer layers and the endosperm cell walls 
of cereal grains (wheat, barley, oat, rye etc.). The non-starch polysaccharides (NSP) found 
in mature cereal grain include the arabinoxylans (AX), which make up the pentosan 
portion of the insoluble fibre fraction and the β-glucans which are major components of 
starchy endosperm and aleurone cell walls. 
AX have been identified in a variety of tissues of major cereals: wheat, rye, barley, oats, 
rice, sorghum (FINCHER and STONE, 1986). Although these polysaccharides are minor 
components of the whole caryopsis, they still account for a substantial fraction of the cell 
walls and thus constitute a major portion of the dietary fibre of wheat flours (SKENDI et 
al., 2011). Wheat varieties differ in AX amount and properties (MASLEN et al., 2007) such 
as average molecular weight and distribution, branching pattern, extractability with water 
(FINNIE et al., 2006) and interaction with other cell wall components such as lignin or 
cellulose (REVANAPPA et al., 2007). 
AX consist mainly of a xylan chain with β-1,4-linked D-xylopyranosyl residues (Xyl) to 
which mostly single α-L-arabinofuranose units (Ara) are linked at the O-2 and/or O-3 
positions of the xylose units as side residues (IZYDORCZYK and BILIADERIS, 1995). In 
wheat AX, approximately 66% of the xylose residues, that form the backbone chain, are 
unsubstituted Xyl (SAULNIER et al., 2007b). Moreover, some Ara units carry ferulic acid 
residues esterified to O-5 of Ara linked to O-3 of the xylose residues (SOSULSKI et al., 
1982). Extractable AX and unextractable AX structures are similar, showing only slightly 
differences in molecular weight and in the Ara/Xyl ratio (IZYDORCZYK and 
BILIADERIS, 1995). 
AX represent the major polysaccharides in the aleurone fraction (65%) of the wheat 
caryopsis, and the arabinose to xylose ratio decreases from the pericarp to the endosperm; 
furthermore AX from the aleurone layer as well as AX from starchy endosperm have a 
lesser degree of branching than acidic AX from pericarp/testa, which may improve their 
solubility and their digestibility (BROUNS et al., 2012; SAULNIER et al., 2007a).  
β-glucans are linear polymers of high molecular weight consisting of D-glucose molecules 
linked by β-(1-4) and β-(1-3) linkages; the presence of β-linkages (1-3) gives to the 
molecule an irregular shape that makes the β-glucans flexible and partially soluble in 
water (PAPAGEORGIOU et al., 2005; SHELAT et al., 2011). 
From a nutritional point of view, as major non-starch polysaccharides of various cereals 
and main constituents of cell walls of wheat, rye, barley and oat, β-glucans and soluble AX 
have nutritional benefits in humans (WARD et al., 2008). The positive effects of AX are 
related to the ability to reduce postprandial blood glucose levels (GARCIA et al., 2007; LU 
et al., 2000), lowering levels of potentially toxic ammonia in the colon and the ability to 
reduce levels of triglycerides in the blood (GARCIA et al., 2006). Over the last two decades 
β-glucans have been considered as bioactive ingredients due to their capacity in lowering 
plasma cholesterol, improving lipid metabolism, and reducing the glycaemic index 
(MӒKELӒINEN et al., 2007; WOOD, 2007). These positive effects increased the popularity 
and consumption of cereal-based foods as well as of many other foods fortified with cell 
wall-enriched grain fractions, β-glucan concentrates and isolates (LAZARIDOU and 
BILIADERIS, 2007).  
Furthermore, the Commission Regulation (EU) No 432/2012 of 16 May 2012 (Official 
Journal of the European Union 25-05-2012) included arabinoxilans and β-glucans in the list 
of authorized health claims. 
In this study, the content of AX and β-glucans in several cereal wholemeal flours was 
determined using different techniques, whose efficacy was compared. 



	

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2. MATERIALS AND METHODS 
 
2.1. Samples 
 
- Five barley varieties, Acquarelle, Braemar, Kelibia, Naturel, USA 2 (waxy variety), 

were provided by Agroalimentare Sud S.p.A. (Melfi, Potenza, Italy). 
-  Five spelt varieties, Ebners Rotkorn, Hercule, Oberkulmer, Redoute, Triventina, 

were provided by Agenzia Regionale per lo Sviluppo Agricolo, Rurale e della Pesca 
(ARSARP, Campobasso, Italy). 

- Five emmer varieties, Molise, Angelo, Garfagnana, Molise Colli, Guardiaregia, were 
provided by ARSARP (Campobasso, Italy). 

- Two durum wheat varieties, Cappelli, Saragolla, were provided by ARSARP 
(Campobasso, Italy). 

- Three soft wheat varieties, Roscetta, Solina 1, Bianchetta, were provided by 
ARSARP (Campobasso, Italy). 

Samples were milled in a refrigerated laboratory mill IKA A 10 Labortechnic (Tanke & 
Kunkel, Gmbh & Co., Staufe, Germany) and stored in aliquots of 100 g at 4°C in a closed 
containers until analysis.  
Data reported for all parameters are the average values of three different aliquots of each 
sample. All results are expressed as % dry weight (d.w.). Moisture content was 
determined according to ICC method 109/1 (ICC, 1995). 
 
2.2. Reagents 
 
NaOH 50% (p/v) was purchased from Baker (Mallinckrodt Baker B.V., Deventer, 
Holland), high-purity laboratory water was produced by means of a MilliQ-Plus 
apparatus (Millipore S.p.A., Milano, Italy); glucose, xylose, arabinose, fructose, standards 
were from Sigma Chemical Co. (St. Louis, MO, USA); all other chemicals and reagents of 
HPLC grade were purchased from Sigma Chemical Co. (St. Louis, MO, USA).  
 
2.3. AX analysis by phloroglucinol method 
 
Total AX analysis was performed as reported by DOUGLAS (1981). Flour (5.0 mg) was 
added to 2 mL of water followed by 10 mL of a solution of glacial acetic acid, hydrochloric 
acid and phloroglucinol in a stoppered tube. The tube was placed in a boiling water bath 
for 25 min and the absorbance of the resulting solution measured at 552 nm and 510 nm. 
 
2.4. AX analysis by orcinol-HCl method  
 
Water soluble AX and total AX analysis by orcinol-HCl method was performed as 
reported by HASHIMOTO et al. (1987). 
Water soluble AX: 100 mg of flour sample were shaken in water at 30°C for 2 h and 
centrifuged. Aliquots of the supernatant were hydrolyzed with 4N HCl at 100°C. The AX 
content was estimated, after treatment in boiling water bath with FeCl3 and orcinol and by 
reading the absorbance at 670 nm.  
Total AX: flour (10 mg) was weighed into a glass tube, where 2 mL of 2N HCl was added, 
and the mixture was hydrolyzed at 100°C for 150 min. After cooling, neutralization was 
carried out by adding 2N sodium carbonate and fermentable sugars were removed by 
means of fresh compressed yeast. The mixture was then centrifuged and an aliquot of the 
supernatant was treated with FeCl3 and orcinol in boiling water bath; the absorbance was 
read at 670 nm. 



	

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2.5. AX analysis by HPAEC-PAD 
 
Determination of arabinoxylans was performed as reported by MESSIA et al. (2016). 
Briefly, for water soluble AX: 100 mg of a flour sample were shaken in 10 mL of water at 
30°C for 2 hours and centrifuged. Aliquots (1 mL) of the supernatant were hydrolyzed 
with 1 mL of 4N HCl for 2 hours. For total AX, flour sample (10 mg) was weighed into a 
glass tube, 2 mL of 2N HCl were added, and the mixture was hydrolyzed at 100°C for 150 
min. After cooling, neutralization was carried out by the addition of 2N sodium carbonate. 
Diluted samples were injected in a chromatographic system equipped with a Rheodyne 
injector (Cotati, CA, USA) with a 25 μL loop. The chromatographic separation was carried 
out with a Carbopac PA1 (250x2 mm) (Dionex Corporation, Sunnyvale, CA, USA) 
analytical column. The chromatographic run (22 min) and the quantitative determination 
were conducted with a 0.25 mL/min flow rate, using a mobile phase of water and 200 mM 
sodium hydroxide (90%-10%). The control of the instrument, the data collection and the 
total quantification were carried out by the chromatographic software Chromeleon 
(Dionex). An HPAEC-PAD Dionex system (Dionex Corporation, Sunnyvale, CA, USA) 
composed of a gradient pump (mod GP50) with an on-line degaser and electrochemical 
detector (model ED40) was used. The flow-through electrochemical cell (Dionex) consisted 
of a 1 mm diameter Gold Working Electrode, a pH reference electrode, and a titanium 
body of the cell as the counter electrode. The optimized time-potential waveform used 
was: 0.1 V at 0-0.40 s, -2.00 V at 0.41-0.42 s, 0.60 V at 0.43 s, -0.10 V at 0.44-0.50 s. 
Total and soluble AX were quantified on the basis of the Ara and Xyl content in the 
hydrolyzed sample: ([Ara] + [Xyl] x D x 0.88), where: D = dilution factor; 0.88 =adjustment 
for free sugar to anhydrous sugar.  
 
2.6. β-glucans analysis  
 
Total β-glucans were determined using the K-BGLU assay kit (Megazyme International 
Ltd., Ireland). Insoluble fractions were determined after extraction of soluble β-glucans 
with water for 2 h at 38°C (ÅMAN and GRAHAM, 1987). Soluble β-glucans were 
calculated as the difference between the total and insoluble components.  
 
2.7. Statistical analysis  
 
All analyses were carried out in triplicate. Results were expressed as means±Standard 
Deviation (SD). 
A one-way analysis of variance (ANOVA) was performed, considering species, variety or 
analytical method as factor. When significant differences (p < 0.05) were detected, Fisher's 
least significant difference (LSD) was computed. All the statistical tests were performed 
using the software IBM SPSS statistics 23. 
 
 
3. RESULTS 
 
3.1. AX analysis and quantification 
 
A comparison between three different analytical methods (HPAEC-PAD and colorimetric 
methods) was carried out in order to devise a practical system for screening of different 
varieties of grains such as barley, wheat, spelt and emmer (Table 1). 
 



	

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Table 1. Total and soluble AX content in different cereal wholemeals determined by three different methods 
(g/100g d.w.±SD). 
 

Sample 
Phloroglucinol Orcinol-HCl 

HPAEC-PAD 
Total Soluble Soluble

AX/ 
Total AX Total AX Total AX 

Soluble 
AX Total AX A/X Soluble AX A/X 

Barley         
Acquarelle 4.92±0.05b 6.42±0.06d 0.09±0.03a 6.18±0.03d 0.85 0.08±0.02a 0.65 0.013 
Braemar 4.30±0.04d 5.94±0.05e 0.06±0.06a 5.21±0.07e 0.75 0.07±0.03a 0.60 0.013 
Kelibia 5.08±0.06c 7.30±0.08b 0.08±0.04a 6.87±0.05b 0.73 0.10±0.03a 0.66 0.015 
Naturel 4.85±0.03b 7.01±0.03c 0.08±0.06a 6.76±0.04c 0.72 0.09±0.04a 0.62 0.013 
USA 2 6.17±0.08a 9.75±0.04a 0.11±0.05a 8.96±0.03a 0.47 0.12±0.05a 0.71 0.013 
mean 5.06bα 7.28aβ 0.08Aβ 6.80aβ 0.70 0.09Aα 0.65 0.013 
Wheat         

Cappelli* 5.10±0.04c 8.78±0.05a 0.09±0.02a 8.21±0.04a 0.78 0.10±0.03a 1.25 0.012 
Saragolla* 5.18±0.03bc 8.17±0.04d 0.09±0.03a 7.90±0.02b 0.80 0.10±0.06a 0.80 0.013 
Roscetta** 5.49±0.05a 8.76±0.05a 0.11±0.03a 8.16±0.10a 0.66 0.12±0.03a 0.71 0.015 
Solina 1** 5.15±0.04bc 8.54±0.07b 0.10±0.04a 7.97±0.04b 0.71 0.12±0.04a 0.71 0.015 

Bianchetta** 5.23±0.06b 8.32±0.04c 0.11±0.03a 7.98±0.03b 0.74 0.13±0.05a 0.71 0.016 
mean 5.23cα 8.51aα 0.10Aα 8.04bα 0.74 0.11Aα 0.84 0.014 
Spelt         

Ebners 
Rotkorn 4.18±0.05

b 5.57±0.04b 0.14±0.04a 5.41±0.05a 0.66 0.11±0.02a 0.77 0.020 

Hercule 4.29±0.06a 5.97±0.05a 0.14±0.03a 5.34±0.07a 0.68 0.12±0.02a 0.85 0.022 
Oberkulmer 3.99±0.04d 5.18±0.06c 0.12±0.03a 4.75±0.05c 0.64 0.12±0.04a 0.95 0.025 

Redoutè 3.89±0.07c 5.13±0.05c 0.14±0.03a 4.60±0.06d 0.61 0.10±0.02a 0.80 0.022 
Triventina 4.20±0.04b 5.63±0.10b 0.11±0.02a 5.03±0.03b 0.65 0.11±0.03a 0.78 0.022 

mean 4.11cβ 5.50aγ 0.13Aα 5.03bγ 0.65 0.11Aα 0.83 0.022 
Emmer         
Molise 3.65±0.04c 6.48±0.04b 0.23±0.04a 5.89±0.04b 0.67 0.18±0.05a 1.04 0.031 
Angelo 3.76±0.03b 5.26±0.06c 0.11±0.05b 5.03±0.05d 0.70 0.10±0.06b 1.16 0.020 

Garfagnana 4.12±0.09a 5.63±0.03d 0.11±0.03b 5.29±0.03c 0.62 0.11±0.05b 1.00 0.021 
Molise Colli 4.06±0.05a 5.31±0.05c 0.09±0.05b 4.90±0.08e 0.58 0.07±0.04b 1.10 0.014 

Guardiaregia 3.60±0.06c 6.76±0.07a 0.12±0.04b 6.32±0.04a 0.69 0.08±0.05b 1.40 0.013 
mean 3.84cγ 5.89aγ 0.13Aα 5.49bγ 0.65 0.11Aα 1.14 0.020 

 
*durum wheat; **soft wheat 
Different superscript letters (total AX=lower case, soluble AX=upper case) between species means within a 
row indicate statistically significant differences at P< 0.05. 
Different superscript letters between means (species=Greek font, variety=italic font) within a column 
indicate statistically significant differences at P< 0.05. 

 
 

The systematic quantification of AX in cereal wholemeal flours revealed substantial 
differences between the colorimetric procedures. Although phloroglucinol and orcinol-
HCl procedures are both based on colorimetric assessments, for the measurement of total 
AX, the phloroglucinol method provided values that were significantly lower than those 
of the orcinol-HCl method. This underestimation of total AX can be attributed to the type 
of extraction performed for the phloroglucinol assay, that leads to a relevant release of 
hexoses from starch hydrolysis, which greatly exceeds pentoses, influencing their 



	

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evaluation. In the orcinol-HCl method, the high glucose concentrations are removed by 
the action of the yeast Saccharomyces cerevisiae, thus providing a better assessment of the 
total AX; additionally the orcinol-HCl method allows to evaluate not only the total AX but 
also the soluble AX, that cannot be quantified with the phloroglucinol method.  
A significant advantage of the HPAEC-PAD method is to provide more detailed 
information, as it offers the possibility to assess the content of individual sugars Ara and 
Xyl, which are constituents of the AX chain, and it allows to calculate the ratio Ara/Xyl 
(A/X), an important factor related to the behavior of the flour during technological 
processes. HPAEC-PAD assessments also give a more accurate estimation of the sugars 
present in the chain of AX without suffering problems caused by glucose interference, thus 
providing a more accurate and precise quantitative analysis. Finally, the HPAEC-PAD can 
be applied to matrices with high contents of AX (bran) as well as to refined flour (low AX 
content).  
To sum up, the assessment made using the phloroglucinol is not reliable, whereas the 
values of total and soluble AX found in varieties of barley, wheat, spelt and emmer by 
using of either the orcinol-HCl or HPAEC-PAD methods are similar and comparable to 
the values of AX reported in the literature (BERGER and DUCROO, 2005, HENRY, 1987) 
for these cereals.  
GEBRUERS et al. (2008) have published data about the content of AX in refined flours and 
in bran of wheat, spelt and einkorn showing a comparable value of total AX in the 
different types of flour examined. Instead, the results obtained in this trial show a much 
lower content of total AX in spelt an emmer (≈ 5.26%) compared to barley and wheat 
(6.80% and 8.04% respectively). This is in spite of the fact that spelt and emmer are 
phylogenetically close to wheat.  
The data obtained also show a generally close relationship between AX content and cereal 
varieties. Among barleys, USA2, a waxy (i.e. having a low amylose content) variety has 
the highest content of β-glucans (9.5%) (Table 2) and of total AX (6.2%). The content of AX 
in barley also depends on genetic and environmental factors (IZYDORCZYK and 
DEXTER, 2008) but appears to be less variable than that of β-glucans. 
The HPAEC-PAD method allows to compute the ratio A/X which indicates the degree of 
branching in the polymer chain, thus permitting to deduce information about the AX 
structure of different species and varieties. A high A/X ratio corresponds to a higher 
proportion of mono-substituted xylosyl residues and a lower proportion of unsubstituted 
xylosyl residues. The degree of substitution of xylan backbone is relevant for predicting 
the cereal behavior when subjected to different technological processes. Emmer varieties 
showed an A/X ratio of soluble AX (1.14), much higher than the ratios of barley (0.65), 
wheat (0.84) and also spelt (0.83). 
From a technological point of view, the quantification and the assessment of variations in 
the overall AX content is relevant because AX is generally considered to have a significant 
effect on wheat functionality and also to affect suitability of flours for certain applications 
(GEBRUERS et al., 2008). Cereal varieties rich in AX, have a strong potential for the 
production of healthy or even health promoting food products that contain not only a high 
overall dietary fiber content but also increased levels of soluble dietary fiber as well as 
prebiotic oligosaccharides which are produced by the in situ action of xylanases 
(GEBRUERS et al., 2008).  
 
 
 
 
 
 



	

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3.2. β-glucans analysis and quantification 
 
Total, insoluble and soluble β-glucans were quantified in different cereals (barley, wheat, 
spelt, emmer) flours (Table 2). Results showed a different β-glucans distribution in tested 
species and between waxy and non waxy barley varieties. 
 
 
Table 2. β-glucans content, AX+ β-glucans and AX/β-glucans in different cereal wholemeals (g/100g 
d.w.±SD). 
 

Sample 
β-glucans  

Total Insoluble Soluble Soluble/ Insoluble 
AX+β-

glucans AX/β-glucans 

Barley       
Acquarelle 4.43±0.13c 1.50±0.01e 2.94 1.97 10.61 1.40 
Braemar 3.89±0.11e 1.92±0.07b 1.97 1.03 9.07 1.34 
Kelibia 4.17±0.07d 1.61±0.02d 2.57 1.60 11.04 1.65 
Naturel 4.67±0.11b 1.81±0.04c 2.86 1.58 11.43 1.45 
USA 2 9.49±0.09a 3.42±0.08a 6.08 1.78 18.45 0.94 
mean 5.33A 2.05A 3.28 1.59 12.12 1.36 
Wheat       

Cappelli * 0.52±0.03c 0.41±0.03b 0.11 0.27 8.73 15.79 
Saragolla * 0.42±0.02d 0.22±0.01c 0.20 0.93 8.32 18.81 
Roscetta ** 0.60±0.05b 0.42±0.06b 0.19 0.45 8.76 13.60 
Solina 1 ** 0.53±0.03c 0.37±0.03b 0.16 0.42 8.50 15.00 

Bianchetta ** 0.79±0.01a 0.60±0.03a 0.19 0.31 8.77 10.10 
mean 0.57B 0.40B 0.17 0.47 8.62 14.66 
Spelt       

Ebners Rotkorn 0.68±0.02ab 0.44± 0.05ab 0.24 0.55 6.09 7.96 
Hercule 0.63±0.05b 0.42± 0.04ab 0.21 0.50 5.97 8.48 

Oberkulmer 0.70±0.02a 0.49± 0.03a 0.21 0.43 5.45 6.78 
Redoutè 0.65±0.03ab 0.47± 0.03a 0.18 0.38 5.25 7.08 

Triventina 0.57±0.02c 0.40±0.03b 0.17 0.43 5.60 8.82 
mean 0.65B 0.44B 0.20 0.46 5.67 7.82 

Emmer       
Molise 0.48±0.03b 0.37±0.01a 0.12 0.32 6.37 12.27 
Angelo 0.41±0.02c 0.29±0.05b 0.12 0.42 5.44 12.27 

Garfagnana 0.37±0.01c 0.28±0.03b 0.09 0.30 5.66 14.30 
Molise Colli 0.53±0.02a 0.35±0.03ac 0.18 0.51 5.43 9.24 

Guardiaregia 0.48±0.03b 0.30 ±0.02bc 0.18 0.61 6.8 13.17 
mean 0.45B 0.32B 0.14 0.43 5.94 12.25 

 
*durum wheat; **soft wheat. 
Different superscript letters between means (species=upper case, variety=lower case) within a column 
indicate statistically significant differences at P< 0.05. 
 
 
In barley, the variable β-glucans content can be influenced by genotype, culture practices 
and environmental growing conditions (NEWMAN and McGUIRE,1985; Newman and 



	

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Newman, 2008). The presence of waxy genes can influence polysaccharides biosynthesis 
and their composition in the kernel. In the “normal” barley genotype, the starch is 
composed of about 25% of amylose and 75% amylopectin while in the waxy genotypes the 
starch is almost exclusively composed of amylopectin (95-100%). The reduced level of 
starch is usually accompanied with an increased content of β-glucans in the cell walls of 
the starchy endosperm (ANDERSSON et al., 2008). In fact, according to many research 
reports (ABDEL-AAL et al., 2005; WOOD et al., 2003) a waxy barley variety (USA2) 
showed a β-glucans content which was twofold that of non waxy varieties.  
Comparing the data from different species (Table 2), it is evident that there is a significant 
difference in the average content of total β-glucans among barley and wheat, spelt and 
emmer (5.33% d.w. for barley, 0.57% d.w for wheat, 0.65% d.w. for spelt and 0.45% d.w. 
for emmer), confirming the data reported in the literature by other authors (SKENDI et al., 
2003).  
With regard to soluble β-glucans content, varieties of wheat, spelt and emmer are 
characterized by very low levels of soluble β-glucans (average: 0.17%, 0.20% and 0.14% 
d.w., respectively), probably related to a higher ratio of cellotriose/cellotetraose, which 
generally amounts to 4.6 and 3.3 respectively in wheat and barley. Statistically, although 
the distribution of cellotriose and cellotetraose units linked by β (1-3) is random (WOOD et 
al., 2003), the probability of a repetition of ordered cellotriose units is greater in wheat than 
in barley and oats (CUI et al., 2000). Since the structure is more ordered and more inter 
chain associations are favoured, the water solubility of β-glucans derived from wheat is 
lower than that of other cereals (LAZARIDOU and BILLIADERIS, 2007). 
The soluble β-glucans content affects the soluble/insoluble ratio, which is greater in barley 
(1.59) than in wheat, spelt and emmer (0.47, 0.46 and 0.43 respectively). Data on total 
content of AX + β-glucans and their ratio (AX/β-glucans) (Table 2) showed significant 
differences between the analyzed wholemeals. The high content of AX + β-glucans in 
barley corresponded to a low AX/β-glucans ratio, which is further reduced in the waxy 
barley variety USA 2 (0.94). While β-glucans are mainly present in barley, the AX are 
distributed in all the analyzed species and varieties. The relevant presence of two 
polymers in barley makes this cereal an excellent ingredient for the preparation of 
products with an increased content of total and soluble dietary fiber, capable of enhancing 
both the physiological effects and health benefits (VERARDO et al., 2011a; VERARDO et 
al., 2011b; VITAGLIONE et al., 2010). 
Moreover, β-glucans and AX are the chief structural constituents of cell wall in various 
tissues of the barley grain. In the starchy endosperm of mature barley grain, the matrix-
phase AX and β-glucans may represent up to 85% of total cell wall polysaccharides. The 
endosperm cell walls are mainly made up of β-glucans and contains a smaller amount of 
AX, while aleurone cell walls are composed primarily of AX (67-71%), with smaller 
amounts of β-glucans (26%). Various studies have been carried out as to the possibility of 
producing barley flour enriched in β-glucans using air classification and dry milling 
methods to produce an enriched flour that can be used for producing different cereal 
products, such as bread, muffins, and pasta (MARCONI et al., 2000).  
 
 
4. CONCLUSIONS 
 
The present study revealed a wide variability in the content of AX and β-glucans in 
wholemeal of different cereal species and varieties.  



	

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Barley varieties showed a higher β-glucans and AX content compared to other cereal 
species/varieties. The assessment of the A/X ratio for AX and soluble/insoluble β-glucans 
ratio, which directly affect the behavior of cereal flours during transformation, are useful 
for deciding the end use of grains and evaluating the nutritional quality of the analysed 
grains.  
The HPAEC-PAD method proved to be advantageous compared to colorimetric methods. 
It allows to compute the ratio A/X which indicates the degree of branching in the polymer 
chain, thus permitting to deduce information about the AX structure of different species 
and varieties. 
The quantification and the assessment of variations in the overall AX content is relevant 
because AX is generally considered to have a significant effect on cereal flours 
functionality and also to affect suitability of flours for certain applications.  
Cereal varieties rich in AX and β-glucan, have a strong potential for the production of 
healthy or even health promoting food products that contain not only a high overall 
dietary fiber but also increased levels of soluble dietary fiber, that should meet the health 
claims listed in the Commission Regulation (EU) No 432/2012. 
 
 
ACKNOWLEDGEMENTS 
 
We would like to thank Agroalimentare Sud S.p.A. (Melfi (PZ), Italy) and Agenzia Regionale per lo Sviluppo Agricolo, 
Rurale e della Pesca (ARSARP), (Campobasso, Italy) for providing varieties of barley, wheat, spelt and emmer. 
This research was supported by MIUR (Italian Ministry of Instruction, University and Scientific Research) as part of the 
PRIN Project 2010 No. 2010ST3AMX_002. 
 
 
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Paper Received August 5, 2016  Accepted October 14, 2016