Chemical and physical characteristics ofdifferent barley samplesAnnica AM Andersson,1* Cajsa Elfverson,2 Roger Andersson,1 Sigurd Regner2 andPer Aman1

1Swedish University of Agricultural Sciences, Department of Food Science, PO Box 7051, S-750 07 Uppsala, Sweden2Swedish University of Agricultural Sciences, Department of Agricultural Engineering, PO Box 7033, S-750 07 Uppsala, Sweden

Abstract: Eight different barleys, including covered and naked samples containing low, normal and

high amylose starches as well as a sample with low starch and high b-glucan content and a malting

barley, were examined both from a chemical and physical perspective. In the chemical characterisa-

tion of the samples, analyses of nutrients were performed, while in the physical characterisation,

weight of individual kernels, sieving fractions, bulk density, terminal velocity by pneumatic

classi®cation and parameters from a Single Kernel Characterization System (SKCS) were analysed.

Results were evaluated by principal component analysis (PCA). The major trend found was that hull

content and endosperm composition varied independently of each other. Constituents found mainly in

the hull were positively correlated with each other, but negatively with bulk density and the 95%

quantile of terminal velocity. There was a positive correlation between average value and standard

deviation of grain mass, fat and starchy endosperm components such as extractable dietary ®bre

residues and b-glucan. The latter variables were negatively correlated to b-glucan extractability.

# 1999 Society of Chemical Industry

Keywords: barley; grain characteristics; PCA

INTRODUCTIONThe increasing demand for high-quality barley as feed,

food and industrial raw material has led to the

development of many different cultivars of barley.

Barley is rich in spontaneous and induced mutants

that have been used throughout the world in different

barley breeding programmes.1Mutant kernel traits

that affect end-use quality are, for example, high

protein content, high lysine content,2 low and high b-

glucan content,3 waxy endosperm4 and high amylose

starch.5

Barley differs greatly in chemical characteristics, due

to genotype and environment and the interaction

between the two. Wide ranges in chemical composi-

tion of barley have been reported.6±8 In normal

covered barley, starch is the major constituent

accounting for about 600gkgÿ1 of dry matter,

followed by total dietary ®bre and protein with about

200 and 110gkgÿ1, respectively. Fat, ash and low

molecular weight sugars are minor components con-

stituting about 30, 20 and 40gkgÿ1 of dry matter,

respectively.6 b-Glucan and arabinoxylan are impor-

tant dietary ®bre constituents. The content of b-glucan

has been reported to vary between 30 and 70gkgÿ1

and the content of arabinoxylan between 40 and

70gkgÿ1.4,8,9

Most physical characteristics of barley, as well as of

other grains and seeds, are normally distributed.10

Although the difference between individual grains in a

bulk sample may vary considerably, usually only the

mean values are measured. The sample is thereafter

treated as if it was homogenous. 1000 Kernel weight is

often used to determine differences in grain mean

mass between samples or varieties and has been

reported to vary between 36 and 54g.11 In many cases

far less than 1000 grains are weighed, leading to an

increase of the 95% con®dence interval of the mean.12

Sieving is a method used either to clean, sort or

grade a sample. Sieve openings with different shapes

can be used with different sieving results. When using

sieves with oblong openings the least dimension, ie the

thickness of a barley grain, is the separating factor. The

mean thickness of barley grains has been reported to

vary between 2.5 and 2.9mm.11 Bulk density is

in¯uenced by, for example, moisture content, grain

shape, surface characteristics and protein content.13

The presence of a hull in¯uences both grain shape,

surface characteristics and packing ef®ciency of the

Journal of the Science of Food and Agriculture J Sci Food Agric 79:979±986 (1999)

* Correspondence to: Annica AM Andersson, Swedish University of Agricultural Sciences, Department of Food Science, PO Box 7051, S-75007 Uppsala, SwedenContract/grant sponsor: Swedish Farmers Foundation for Agricultural Research(Received 19 February 1998; accepted 13 November 1998)

# 1999 Society of Chemical Industry. J Sci Food Agric 0022±5142/99/$17.50 979

grains. Naked grains such as wheat and rye generally

have a higher bulk density than covered barley and

oats;11 95% hull-less barley has been reported to have

signi®cantly higher bulk density than 50% hull-less

barley.14

Terminal velocity is equivalent to the velocity of a

vertical air stream which ensures an equilibrium

between the weight of a grain and the force of the air

stream. It is in¯uenced by different properties of the

grain, eg shape, ratio between weight and cross-

sectional area and surface texture.11,15 The terminal

velocity of irregular shaped grains cannot be calculated

theoretically with suf®cient accuracy and it is therefore

necessary to determine it experimentally. A mean

value for terminal velocity of barley grains is reported

to be 7.6msÿ1 compared to 8.5msÿ1 for wheat.10

In this study we have examined samples of eight

different barley cultivars, of which most were new and

needed to be studied in greater detail. They were also

chosen to represent a wide range of different properties

in order to cover a signi®cant part of the variation

existing in barley. To our knowledge only a few studies

including both chemical and physical data have been

performed before,16,17 but none of these included as

many different analyses as this investigation. The aim

of this work was to study the variation and to ®nd

correlation between the chemical and physical charac-

teristics of the eight different barley samples.

EXPERIMENTALMaterialThe barley (Hordeum vulgare L) cultivars Golf, High

amylose Glacier, SW 906129, Karin, SW 8775,

Hashonucier and Bz 489-30 were obtained from

SvaloÈf Weibulls AB, Sweden, while Prowashonupana

was obtained from ConAgra Inc, USA. The barley

cultivars and their characteristics, according to the

supplying companies, are presented in Table 1. The

naked cultivars Hashonucier and Prowashonupana

contained some grains with the hull remaining after

threshing (30% and about 10%, respectively) and were

therefore treated in an oat dehuller before analysis.

After dehulling the content of partly hulled grains was

10% and 0%, respectively.

Chemical analysesPrior to analysis, representative grain samples (100g)

were ground in a Tecator cyclone mill to pass a 0.5mm

screen. All chemical analyses are reported on a dry

matter basis as an average of duplicate analyses. Dry

matter content of the ground grains was determined by

oven-drying at 105°C for 5h. Starch was determined

enzymically18 while ash and crude protein (N�6.25)

were analysed according to standard methods.19

Crude fat was extracted with petroleum ether in a

Tecator Soxtec System HT (Tecator AB, Sweden)

after acid hydrolysis with 3M HCl.20 Dietary ®bre,

de®ned as the sum of non-starch polysaccharide

residues, amylase-resistant starch and Klason lignin,

was analysed essentially according to Theander et al,21

but with some modi®cations to separate the extrac-

table and unextractable fractions.22

Total and unextractable b-glucan were determined

enzymically according to AÊ man and Graham.9 The

extractability of b-glucan was calculated as the

difference between total and unextractable b-glucan,

divided by total b-glucan. Content of cellulose was

calculated as the difference between total glucose

residues in the dietary ®bre analysis and total b-glucan,

and content of arabinoxylan as the sum of arabinose

and xylose residues.

Analyses of physical characteristicsA representative sample of about 10000 grains was

taken from each barley. The grains were weighed by

use of an automatic sorter23 which weighed each grain

individually (resolution setting of the balance 0.5mg).

A personal computer controlled the process, recorded

the mass of the grains and determined the distribution

of mass of the individual grains for each sample. Three

representative samples of about 100g of each barley

were sieved for 3min in triplicates in a `Sortimat'

laboratory sieve (Pfeuffer, Tiefenstockheim, Ger-

many) with oblong openings (2.8, 2.5 and 2.2mm).

The bulk density was measured with a 1l split cylinder

chondrometer (Hartner, Albstadt-Ebinger, Germany)

on two representative samples for each barley. The

moisture content was determined on unground grains

by oven-drying at 130°C for 20h.24

The terminal velocity was measured in a pneumatic

Table 1. The different barley cultivars and theircharacteristics

Cultivar Characteristics

Covered

Golf Normal starch, 2-rowed

High amylose Glacier High amylose starch, 6-rowed

SW 906129 High amylopectin (waxy) starch, 2-rowed

Karin Normal starch, 6-rowed, malting quality

Naked

SW 8775 Normal starch, 2-rowed

Hashonucier High amylose starch, 2-rowed

Bz 489-30 High amylopectin (waxy) starch, 2-rowed

Prowashonupana High amylopectin (waxy) starch, low starch, 2-rowed

980 J Sci Food Agric 79:979±986 (1999)

AAM Andersson et al

classi®er (constructed and built at the Department of

Agricultural Engineering) in which the velocity of the

air stream could be adjusted. A representative sample

of about 150g of each barley was classi®ed. The

fraction of the sample which had lower terminal

velocity than the actual velocity of the air stream was

carried by the air stream to a cyclone where the grains

were separated from the air and passed to a settling

container. Each fraction was weighed and a cumula-

tive frequency of the distribution of terminal velocity

was calculated.

Two samples of 300 grains of each barley, except

High amylose Glacier, whose grains were too large,

were analysed in a Single Kernel Characterization

System, SKCS 4100 (Perten Instruments North

America Inc, Reno, USA). In this system, mass,

diameter, hardness and moisture content of the

individual grains were measured and thereafter a mean

value was calculated for each sample. The system is

developed for wheat and no adjustments were made

for measurements of barley.

Statistical analysesIn order to study the variation in chemical composition

and physical characteristics and to ®nd correlation

between different variables, principal component

analysis (PCA, SIRIUS Pattern Recognition system

A/S, Bergen, Norway) was performed. The following

variables were included: content of starch; ash; crude

protein; crude fat; total dietary ®bre; extractable and

unextractable dietary ®bre; extractable and unextract-

able dietary ®bre polysaccharide residues; Klason

lignin and total, extractable and unextractable b-

glucan, as well as extractability of b-glucan; average

value and standard deviation (SD) of grain mass;

skewness of the distribution of grain mass; sieve

distribution; bulk density; 5%, 50% and 95% quan-

tiles of terminal velocity and mass; diameter and

hardness of grains from the SKCS analysis.

RESULTSChemical analysesGross chemical composition of the eight barley

samples is shown in Table 2. Starch was generally

the major constituent (521±644gkgÿ1), followed by

total dietary ®bre (135±238gkgÿ1) and protein (87±

131gkgÿ1). In Prowashonupana the main component

was total dietary ®bre (345gkgÿ1), followed by starch

(239gkgÿ1) and protein (181gkgÿ1). Fat and ash were

only minor constituents in all samples (22±62gkgÿ1

and 20±26gkgÿ1, respectively).

With the exception of Prowashonupana, the naked

barley samples were lower in ash and dietary ®bre and

higher in fat, protein and starch, compared to the

covered barley samples. The highest content of ash

was found in Karin, while the highest content of total

dietary ®bre and fat was found in High amylose

Glacier. Both high amylose barley samples were higher

in total dietary ®bre than the normal and waxy barley

samples. The content of protein was highest in

Hashonucier, while the content of starch was highest

in SW 8775. The lowest content of starch was found in

the high amylose barley samples. Prowashonupana

was a deviant, with a very low content of starch, and

consequently higher contents of ash, fat, protein and

dietary ®bre than any of the other barley samples.

The content of unextractable dietary ®bre was about

2.5±3.5 times higher than the content of extractable

dietary ®bre for the covered barley samples, and 1.5±2

times higher for the naked samples (Table 3). High

amylose barley samples were higher in both extractable

and unextractable dietary ®bre, compared to normal

and waxy samples, Prowashonupana excepted. Karin

had a remarkably low content of extractable dietary

®bre, especially glucose residues, compared to the

other barley samples. Glucose was the dominating

residue of both extractable and unextractable dietary

®bre in all samples. Arabinose and xylose residues

were also found in relatively large amounts. The

calculated content of cellulose and arabinoxylan was

higher in covered than in naked barley samples,

Prowashonupana excepted. The content of total and

unextractable b-glucan was higher in the waxy and the

high amylose barley samples than in the normal

samples, with the highest content found in Prowa-

shonupana. The lowest content of b-glucan was found

in Karin. The extractability of b-glucan was lower in

the high amylose barley samples than in the normal

and the waxy samples, but lowest in Prowashonupana

at only 8%. Rhamnose and fucose residues were only

found in trace amounts in all samples, while mannose,

Table 2. Chemical composition of the barleycultivars (gkgÿ1 dry matter)

Cultivar Ash Fat Protein Starch Dietary ®bre

Covered

Golf 23 22 87 638 189

High amylose Glacier 25 35 104 521 238

SW 906129 25 34 105 566 198

Karin 26 22 92 632 198

Naked

SW 8775 23 28 113 644 136

Hashonucier 21 32 131 597 171

Bz 489-30 20 29 113 619 135

Prowashonupana 21 62 181 239 345

J Sci Food Agric 79:979±986 (1999) 981

Chemical and physical characteristics of barley

galactose and uronic acid residues as well as Klason

lignin were found in small amounts. The content of

Klason lignin was higher in the covered than in the

naked barley samples.

Physical characteristicsThe distributions of mass of the individual grains are

presented in Fig 1. High amylose Glacier had the

highest average grain mass and Prowashonupana the

lowest. High amylose Glacier and Hashonucier had

the highest standard deviation (SD) of the mass of the

individual grains and Prowashonupana the lowest

(Table 4). The naked barley samples, with the

exception of Prowashonupana, had signi®cantly high-

er bulk density than the covered ones (P<0.0001)

(Table 4). SKCS hardness index varied between 57.5

(Bz 489-30) and 97.4 (Prowashonupana) (Table 4).

All barley samples were classi®ed as hard grains,

according to this analysis. High amylose Glacier and

SW 906129 had the largest proportion of grains with

least dimension larger than 2.8mm, and Prowasho-

nupana the smallest. All barley samples had only a few

grains with least dimension smaller than 2.2mm

except Karin and Prowashonupana, which had 6.3%

and 95.6%, respectively, in that fraction (Table 5).

The terminal velocity varied quite considerably (Fig

2). The two barley samples with lowest mean mass,

Karin and Prowashonupana, also had the lowest

terminal velocity. However, High amylose Glacier

with the highest mean mass had almost the same

distribution as Prowashonupana. The naked barley

samples, except of Prowashonupana, had the highest

terminal velocity and SW 8775 the highest of them all.

Table 3. Content of extractable and unextractable dietary fibre polysaccharide residues, Klason lignin and total and unextractable b-glucan (gkgÿ1 dry matter)

Covered Naked

Constituent Golf

High amylose

Glacier SW 906129 Karin SW 8775 Hashonucier Bz 489-30 Prowashonupana

Extractable

Arabinose 2.4 4.0 3.3 2.6 3.5 4.5 2.8 7.8

Xylose 3.2 5.6 4.6 3.2 4.9 6.6 3.6 13

Mannose 0.7 1.4 0.9 0.8 1.0 1.4 0.9 3.7

Galactose 0.7 0.8 0.8 0.7 1.1 0.8 0.7 1.8

Glucose 32 49 46 21 32 48 37 123

Uronic acid 1.5 1.7 2.1 1.1 1.5 1.7 1.9 2.4

Totala 40 63 58 29 44 63 46 152

Unextractable

Arabinose 21 23 22 23 17 18 18 38

Xylose 50 57 45 55 27 28 24 61

Mannose 3.6 6.7 3.7 6.7 3.9 4.7 4.2 10

Galactose 2.0 2.3 2.0 2.1 1.6 1.5 1.8 2.9

Glucose 55 67 50 49 33 42 33 67

Uronic acid 2.9 3.4 3.1 3.5 1.9 1.9 1.7 3.3

Klason lignin 15 15 14 17 7.4 11 6.9 10

Totala 149 175 140 169 92 107 89 193

Total b-glucan 47 69 61 28 46 74 56 149

Water

unextractable b-

glucan

25 43 30 13 22 48 26 137

Extractability%b 46.1 38.2 51.1 52.7 51.3 35.1 53.3 8.1

Cellulosec 40 47 35 42 19 16 14 41

Arabinoxyland 77 90 75 83 52 57 48 120

a Including also traces (<0.1gkgÿ1) of rhamnose and fucose.b (Total b-glucan ± unextractable b-glucan)/total b-glucan.c Glucose ± total b-glucan.d Arabinose�xylose.

Figure 1. Cumulative frequency of mass of the individual grains: *,Prowashonupana; &, Karin; ~, Bz 489-30; x SW 906129; —,Hashonucier; ---, Golf; *, SW 8775; &&, High amylose Glacier.

982 J Sci Food Agric 79:979±986 (1999)

AAM Andersson et al

Principal component analysisPCA was used to visualise the variation in the material

and to ®nd correlation between different variables.

Prowashonupana was excluded after a ®rst analysis,

since it was too different from the other barley samples

to make further analysis meaningful (result not

shown). PCA generated two signi®cant principal

components (PC1 and PC2), explaining 39% and

29% of the variance, respectively (Figs 3 (a) and (b)).

A score plot of the relationship between PC1 and PC2

showed that the barley samples could be separated into

two groups, one with the naked barley samples with

positive scores for PC1, and one with the covered

barley samples with negative scores for PC1 (Fig 3

(a)).

The loading plot showed the relationship between

different variables (Fig 3 (b)). All variables included in

the PCA except average values and SD for hardness,

SD for diameter, average values and SD for mass

determined by SKCS, F1, F2, unextractable mannose

residues, extractable uronic acid residues, extractable

galactose residues, extractable b-glucan and extrac-

tability of b-glucan were explained to more than 60%

by PC1 and PC2. The plot showed that the

constituents mainly present in the hull (Klason lignin,

ash, total dietary ®bre, unextractable dietary ®bre and

unextractable glucose, galactose, arabinose, xylose and

uronic acid residues) were found in the upper left

square. All these variables, except total dietary ®bre

and unextractable glucose residues, which are also

typical constituents of the starchy endosperm, were

clustered together and opposite to the variables

describing the 95% quantile of terminal velocity and

bulk density. Endosperm cell wall components (total,

unextractable and extractable b-glucan, extractable

dietary ®bre and extractable glucose, mannose, arabi-

nose, xylose and uronic acid residues) were found in

the upper right square, together with fat content and

the average value and SD for grain mass. The 5%

quantile of terminal velocity and the skewness of the

distribution of grain mass were found opposite to each

other close to PC1, while starch and F4 were found

opposite each other close to PC2.

Objects that appear close together, like Bz 489-30

and SW 8775, have similar values for many of the

variables studied. Objects with large scores for one PC

have large values for variables with large positive

loadings for the same PC, and low values for variables

with large negative loadings. That is, High amylose

Glacier had a large F4 fraction and high content of hull

components, while it had a low starch content. Karin,

SW 8775 and Bz 489-30, on the other hand, had a

small F4 fraction, a low content of hull components

and a high starch content. Hashonucier had a high

Table 4. Grain mass determined with the automaticsorter, bulk density and SKCS hardness index

Automatic sorter

grain mass mga

Cultivar Average SD Bulk densityg lÿ1a SKCS hardness index

Covered

Golf 45.4 9.4 732 69.4

High amylose

Glacier

52.4 11.8 661 not analysed

SW 906129 43.2 8.3 731 70.6

Karin 33.5 8.3 716 73.4

Naked

SW 8775 46.4 9.6 787 60.1

Hashonucier 44.6 11.2 799 81.6

Bz 489-30 40.3 9.5 796 57.5

Prowashonupana 30.5 5.8 684 97.4

a The moisture content of all samples was between 105 and 110gkgÿ1.

Table 5. Relative distribution (weight%)of sieve fractions

F1 F2 F3 F4

Cultivar <2.2mm >2.2mm, <2.5mm >2.5mm, <2.8mm >2.8mm

Covered

Golf 1.1 16.0 53.7 29.3

High amylose Glacier 0.2 6.4 39.0 54.4

SW 906129 0.5 10.2 39.9 49.5

Karin 6.3 34.2 42.9 16.6

Naked

SW 8775 1.2 14.7 54.8 29.2

Hashonucier 2.9 32.9 48.5 15.7

Bz 489-30 2.8 28.6 60.0 8.6

Prowashonupana 95.6 2.6 0.6 0.3

J Sci Food Agric 79:979±986 (1999) 983

Chemical and physical characteristics of barley

protein content. Both high amylose barley samples had

a high content of b-glucan, while the solubility was

low.

DISCUSSIONChemical componentsThe lower content of ash and dietary ®bre, and higher

content of fat, protein and starch in the naked barley

samples is due the absence of a hull. The hull usually

constitutes about 100±130gkgÿ1 of the grain dry

weight25 and consists mainly of cellulose, hemicellu-

lose (xylans), lignin and a smaller quantity of

protein.26 The higher content of protein observed in

naked barley samples has been reported before, as well

as the lower content of dietary ®bre.8,27 The level of

dietary ®bre in naked barley samples, however, has

been shown to be about 25% higher than in pearled

covered barley samples.28 The presence of hull in the

covered barley samples probably also accounts for the

larger proportion of unextractable ®bre/extractable

®bre in these samples compared to naked samples.

The waxy and high amylose barley samples had a

higher total dietary ®bre and b-glucan content than the

samples with normal starch, which is in agreement

with earlier reports.4,8,29 High contents of b-glucan

have been shown to be bene®cial for health, due to its

ability to lower serum cholesterol and blood glucose

levels.30,31 The very high content and low extractabi-

lity of b-glucan in the Prowashonupana sample may be

of special interest in this respect, which has also been

shown by Newman et al32 and Liljeberg et al.33 When

using barley for malt, the content of b-glucan should

be low. A high content of b-glucan may lead to poorer

quality of the beer because of diminished rate of wort

®ltration, haze formation and reduced extraction

ef®ciency.34 Karin is thus a suitable cultivar for

malting, since the content of b-glucan was low

compared to the other barley samples.

Physical characteristicsFor terminal velocity and bulk density, which are both

in¯uenced by several properties, there was a clear

difference between the covered and the naked barley

samples. The naked samples had both higher terminal

velocity and bulk density, with the exception of

Figure 2. Cumulative frequency of terminal velocity: &, Karin; �,Prowashonupana;&, High amylose Glacier; x, SW 906129; ---, Golf; ~, Bz489-30; —, Hashonucier; *, SW 8775.

Figure 3. (a) Score plot and (b) loading plot of the first two principalcomponents from analysis of six different barley samples. DF, uDF andeDF=total, unextractable and extractable dietary fiber; uAra, uXyl, uMan,uGal, uGlc and uUA=unextractable arabinose, xylose, mannose,galactose, glucose and uronic acids residues; KL=Klason lignin; eAra,eXyl, eMan, eGal, eGlc and eUA=extractable arabinose, xylose, mannose,galactose, glucose and uronic acid residues; bG, ubG and ebG=total,unextractable and extractable b-glucan; extrbG=extractability of b-glucan;F1–F4=sieve fractions 1–4; BD=bulk density; S5, S50 and S95=5%, 50%and 95% quantile of terminal velocity; Avg G and SD G=average value andstandard deviation of grain mass; Gskw=skewness of grain mass; Avg Wtand SD Wt=average value and standard deviation of weight measured bySingle Kernel Characterization System; Avg Dia and SD Dia=averagevalue and standard deviation of diameter measured by Single KernelCharacterization System.

984 J Sci Food Agric 79:979±986 (1999)

AAM Andersson et al

Prowashonupana which has an abnormal shape lead-

ing to low values for these parameters. Wheat, which

resembles naked barley, also has both high terminal

velocity and bulk density.11 The 1000-kernel weight

and the mean thickness of the barley cultivars in this

study were generally in the same range as those

reported by Mohsenin.11 Karin was, however, lighter

and Prowashonupana was both lighter and had a lower

mean thickness. Naked barley has been reported to be

a soft grain, when measuring hardness with a

Brabender micro hardness tester.35 In our study, all

cultivars, both covered and naked, were classi®ed as

hard according to the SKCS method. The discrepancy

in results may be explained by differences in the

materials and methods used and that no adjustments

were made, or that our study included cultivars of

barley not used or not available in the ®rst study.

Principal component analysisThis study included samples with very different

characteristics, covering a wide range of the variation

in barley available for various applications. The

numerous analyses made on these samples provided

a good opportunity to study correlation between

different chemical and physical variables. This was

done with PCA, which showed large systematic

variation between samples with a few major trends.

Samples varied in different ways, for example,

Hashonucier had a high content of protein and a low

content of starch, while SW 8775 had a high content of

both protein and starch but a lower content of dietary

®bre. The major trend found was that content of hull

and composition of endosperm were independent of

each other, which is shown by the two arrows in Fig

3(b). The content of starch, protein and endosperm

cell walls was thus not affected by the content of hull

components. Generally, the content of hull was

explained by PC1 and the composition of endosperm

by PC2.

That the average grain mass from the automatic

sorter and from the SKCS analysis are not found close

together in the loading plot is dif®cult to explain. One

possible reason is that the SKCS only weighs 300

grains and that the standard error of the mean mass is

too large to make it possible to detect differences in

mean mass between samples.12 The SKCS is also

developed for wheat and no adjustments were made

before measuring the barley samples.

The variance for the variables close to the origin

(average hardness, extractable galactose residues and

SD for diameter, weight and hardness of the grains)

was minimally explained by PC1 or PC2, due to their

low correlation to other variables. The hull constitu-

ents were negatively correlated to bulk density, as well

as the 95% quantile of terminal velocity. This

correlation may be explained by the fact that the

presence of a hull leads to differences in, for example,

density, grain shape and surface characteristics.11,13,15

Starch content and fraction F4 were found to be

negatively correlated for the barley samples examined

in this study. This means that the barley samples with a

high proportion of large grains (High amylose Glacier

and SW 906129) had a lower content of starch than

the other barley samples, which may be due to a

restricted starch synthesis in these cultivars. There was

a positive correlation between endosperm cell wall

constituents, such as extractable dietary ®bre residues

and b-glucan, and fat and average value and SD of

grain mass. These variables were negatively correlated

to extractability of b-glucan. This negative correlation

is mainly caused by the low extractability of b-glucan

in the high amylose barley samples.

In summary, we found a large variation between the

barley samples and interesting correlations between

chemical and physical characteristics. Conclusions

regarding groups or genotypes of barley should,

however, be drawn with caution because of the limited

number of samples in this study. That physical

characteristics of the individual grains in a bulk sample

are usually normally distributed is well known.10 It

would be interesting to investigate if the chemical

characteristics are distributed in the same way.

Fractionation using one or several physical charac-

teristics may be useful to separate a bulk sample of

cereals into two or more fractions with different

properties of value for the end-users.

ACKNOWLEDGEMENTSThis work was partly ®nanced by the Swedish Farmers

Foundation for Agricultural Research. The authors

also wish to thank BjoÈrn Larsson, Perten Instruments

AB, Huddinge, Sweden, who performed the SKCS

analysis.

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