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Journal of Cereal Science 57 (2013) 193e199

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Journal of Cereal Science

journal homepage: www.elsevier .com/locate/ jcs

Genetic and environmental variability in total and soluble b-glucan in Europeanoat genotypes

Rita Redaelli a,*, Viviana Del Frate b, Silvia Bellato b,c, Giovanna Terracciano b, Roberto Ciccoritti b,c,Christoph U. Germeier d, Ester De Stefanis b, Daniela Sgrulletta b

aCRA, Maize Research Unit, Via Stezzano, 24, 24126 Bergamo, ItalybCRA, Research Unit for Cereal Quality, Via Cassia, 176, 00191 Rome, ItalycCampus Bio-Medico, Rome-University, Via Alvaro del Portillo, 21, 00128 Rome, Italyd Julius Kühn Institute, Federal Research Centre for Cultivated Plants, Institute for Breeding, Research on Agricultural Crops, Erwin-Baur-Str. 27, D-06484 Quedlinburg, Germany

a r t i c l e i n f o

Article history:Received 3 April 2012Received in revised form12 September 2012Accepted 12 September 2012

Keywords:Avena ssp.Genetic variabilityTotal and soluble b-glucanNIRS

* Corresponding author. Tel.: þ39 (0) 35 313132; faE-mail address: rita.redaelli@entecra.it (R. Redaell

0733-5210/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.jcs.2012.09.003

a b s t r a c t

A growing interest in oat (Avena ssp.) soluble fibre (b-glucan) is related to its role in the promotion ofhuman health, and to its utilization in the production of functional foods with increased health benefits.Genetic variability and environmental conditions can exert significant effects on the grain b-glucancontent. In this study 658 European oat genotypes grown in different environments in 2008 or 2009within the European Project “Avena genetic resources for quality in human consumption” were analysedfor total b-glucan content; the soluble fraction of b-glucan was also determined in a sub-set of 165samples. Total b-glucan content ranged from 2.85 to 6.77% d.m. and the soluble fraction from 2.05 to5.29% d.m. The estimated percentage of the soluble fraction ranged from 50.7 to 87.0%. b-glucan contentand solubility were significantly influenced by both genotype and growing environment. Hierarchicalcluster analysis allowed accessions with similar b-glucan compositions to be grouped. The accessionswith the highest contents of both fractions included Avena sativa varieties from several countries andwild species. Finally, the data obtained were used to develop a NIRS calibration equation to predict thecontents of total and soluble b-glucan in both naked and husked genotypes.

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1. Introduction

The interest in oat (Avena ssp.) soluble fibre (b-glucan) isincreasing in relation to its recognised health benefits toconsumers. In particular, b-glucan, by forming a viscous layer asa physical and chemical barrier in the gut and because of its waterholding ability, fermentability and binding of bile acid (Anttila et al.,2004), reduces the absorption rate and consequently blood levels ofcholesterol and glucose. In general, the physiological effects ofsoluble fibres include a reduced risk of coronary heart disease andtype 2 diabetes (Lazaridou and Biliaderis, 2007). The physico-chemical properties as well as the physiological effects of solublefibres depend on their ability to form highly viscous solutions atlow concentrations (Anttila et al., 2004). b-glucan, which is locatedin the cell walls of the aleurone layer and starchy endosperm ofbarley and oats, consists of (1-3)(1-4) b-D-glucan, a polysaccharideformed of D-glucose monomers linked by (1-3) and (1-4) b-

x: þ39 (0) 35 316054.i).

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glycosidic bonds. The (1-3) linkages contribute to the moleculeflexibility and to its high solubility and viscosity (Lazaridou andBiliaderis, 2007). Izydorczyk et al. (1998) showed that structuraldifferences existed between soluble and insoluble b-glucan whichare specifically associated with the ratio of b (1-4)/(1-3) linkages.Oat b-glucan shows high viscosity and shear timing behaviour andits concentration and molecular weight influence its solubility andproperties in solution (Johansson et al., 2000). Wood (2010)underlined the importance of controlling the factors that maycause structural changes in b-glucan, modifying its rheologicalbehaviour and probably also its physiological properties. In fact,processing may change the properties of b-glucan by affecting itsextractability or solubility and molecular weight (Anttila et al.,2004) and the effects by degrading b-glucanases (Anderssonet al., 2004).

As the interest in oat products in the healthy foods market isincreasing, the demand for raw materials with particular healthbenefits requires specific breeding programmes aimed at therelease of improved oat cultivars which meet the needs of foodindustries. As a first step the existing variability in bioactivecompounds in crop germplasm has been evaluated. Oat b-glucan

Table 1List of the oat species considered in this study: genome classification, number ofaccessions analysed and range of variation of mean values for both total and solubleb-glucan (% d.m.) and for seed weight (mg).

Species Genome Total b-glucan Soluble b-glucan Seedweight

No.Accessions

Range No.Accessions

Range Range

Diploid, 2n ¼ 14canariensis Ac 1 3.57 1 2.61 13.7damascena Ad 1 6.77 1 5.29 8.6hirtula As 3 4.99e6.28 3 3.62e5.04 7.7e8.8strigosa As 46 2.85e6.23 20 2.45e3.95 7.0e34.8wiestii As 1 6.55 1 5.05 9.4

Tetraploid, 2n ¼ 28abyssinica AB 5 3.58e5.12 2 3.19e3.78 13.7e38.2barbata AB 3 4.51e5.46 2 2.88e4.48 6.5e32.0

Hexaploid, 2n ¼ 42byzantina ACD 23 2.88e4.94 5 2.50e3.59 20.1e42.5fatua ACD 12 3.20e5.90 8 2.67e4.49 15.7e25.2hybrida ACD 1 4.23 1 3.41 23.2sativa subsp. ACD 546 3.02e5.74 110 2.05e4.18 8.3e45.6sterilis ACD 5 3.90e5.22 4 3.23e4.48 22.3e51.7

R. Redaelli et al. / Journal of Cereal Science 57 (2013) 193e199194

content was determined in several studies in the past, includinglines and cultivars from different countries (Ajithkunar et al., 2005;Cho and White, 1993; Lee et al., 1997; Peterson et al., 2005) andaccessions of wild species (Cho andWhite, 1993; Miller et al., 1993;Welch et al., 2000). Recently, in the framework of the HEALTH-GRAIN diversity screen, Shewry et al. (2008) characterized five oatcultivars (one naked and four husked), grown in Martonva’sár,Hungary in 2005, for a wide set of phytochemicals: phenolics,tocols, sterols, dietary fibre, b-glucan, and total and water-extractable arabinoxylans. Gajdosova et al. (2007) also reportedthe content of soluble b-glucan in a group of 33 oat cultivars (fournaked and the rest husked). Differences in the solubility propertiesof b-glucan in different oat genotypes may affect their exploitationin foods designed to increase b-glucan consumption (Tiwari andCummins, 2009). However, in general, there have been few largescale studies of the variation in the content of bioactive compo-nents of oats.

The European project “Avena genetic resources for quality inhuman consumption” (AVEQ), was launched in 2007 and involved15 partners from nine different countries. It was focused on theevaluation, characterisation and documentation of geneticresources of oats, both cultivated and wild Avena species. A majorfocus was the description of traits important for the quality of oatsin human consumption, including protein, fat, minerals, dietaryfibre (especially b-glucan), antioxidants and phenolic compounds,which had been poorly explored in the past. These traits wereconsidered relevant to the aim of breeding high quality oat culti-vars, in order tomeet the increasing demand for healthy food. Moreinformation about this project can be found at the website: http://aveq.jki.bund.de/aveq/.

The present study reports the variability in b-glucan content andcomposition in the AVEQ working collection, representing a widerange of the genetic diversity present in European commercial oatcultivars and gene bank accessions. The accessions were grown in2008 or 2009 in different environments across Europe, allowing theeffects of genotype and environment to be evaluated. In particular,knowledge of the variability in the soluble b-glucan fraction, whichis associated with its physicochemical properties, is crucial for theindustries in order to predict its behaviour in the production of oat-based functional foods. Finally, the effectiveness of NIRS (NearInfrared Reflectance Spectroscopy) as a rapid screening tool forsimultaneously evaluating total and soluble b-glucan in oat groatswas investigated.

2. Materials and methods

2.1. Plant material

658 oat genotypes were analysed in this study. The accessions,their species, name, origin, and year of release are listed inSupplemental Table S1. They belonged to 12 different species, andincluded commercial cultivars released in the past two centuries,minor cultivated species and wild species from many gene banks(Table 1). Eleven commercial cultivars from different countrieswere chosen as standards: Argentina and Genziana (Italy), Auteuiland Evora (France), Belinda (Sweden), Ivory (Germany), Jaak(Estonia), Krezus (Poland), Mina (Bulgaria), Mures (Romania), Saul(Czech Republic). Mina and Saul are naked cultivars, all the othersare husked.

2.2. Field experiments

The samples for the biochemical analyses were harvested fromthree different field experiments each year, representing the envi-ronments of North (Estonia and Sweden), Central (Poland and

France) and South Europe (Bulgaria and Romania). The agronomicaldetails of the locations are reported in Table 2. The accessionsconsidered in this study were sown in single plots, whereas the 11standard cultivars were grown in five replicates in each location inboth years (augmented block designs). Chemical analyses of thestandard cultivars were carried out on the samples harvested fromfive locations.

2.3. Chemical analyses

All determinations were carried out on duplicate samples. Analiquot of each sample was de-hulled andmilled to a particle size of0.5 mm using a Perten mill (Sweden). b-glucan concentration wasmeasured according to the enzymatic method of McCleary andCodd (1991) using a Megazyme b-glucan kit. The insoluble frac-tion of b-glucan was extracted by incubation for 120 min withdistilled water at 38� following the method of Åman and Graham(1987); soluble b�glucan content was obtained by subtractinginsoluble from total b-glucan content as also reported by Lee et al.(1997). Moisture was determined in the milled oat samples usinga thermal balance (Sartorius MA 40, Goettingen, Germany). All usedreagents were of analytical spectrophotometric grade (Carlo Erba,Rome, Italy). Enzymatic b-glucan assay kits (mixed linkage b-glucan, K-BGLU 07e11) were purchased from Megazyme Interna-tional Ireland.

2.4. Near Infrared Reflectance Spectroscopy (NIRS) analysis ofmilled oat groats

NIRS calibration models developed using the PLS (Partial LeastSquare) regression method were used to measure total and solubleb-glucan content. The collection of reflectance spectra was per-formed with Foss NIR-system model 6500 (FossItalia, Padua, Italy),which extends measurements into the visible range from 400 to2500 nm scanning at 2 nm intervals. The analyses were made onmilled groat samples using a sample transport module. Spectracollection, manipulation andwavelength selectionwere carried outusing WinISI Project manager v.1.50 software (Infrasoft Interna-tional LLC, State College, PA), using the partial least squares (PLS)algorithm. The calibration curves were developed choosing about

Table 2Agronomic protocols applied in the locations of the field experiments held in 2008 and 2009.

Location Sowing date Plotsize m2

Seeds m�2 Pre-crop FertilizationKg ha�1

Herbicide Insecticide

Northern EuropeJögeva, Estonia 58�440N, 26�230E May 2, 2008 2 e e N 70, P 16, K 29 Lintur 120 g L�1 þ

MCPA 500 ml ha�1Proteus 600 ml ha�1

Svalöv, Sweden 55�930N, 13�100E May 13, 2009 1.25 400 e N 125 e e

Central EuropeRadzików, Poland 50�490N, 16�520E April 7, 2008 2.5 400 e PRP EBV 3.5 L ha�1 Chwastox extra 300

SL, 2.5 -3.0 L ha�1Decis 2.5 EC 0.25 L ha�1

Clermont-Ferrand, France45�470N, 03�100E

March 31, 2009 e 342 Sunflower N 33.5, P 20, K 30 e Foxpro D andDecis Protech

Southern EuropeSadovo, Bulgaria 42�800N, 24�560E March 31, 2008 2.5 400 e N 50 2,4 D 2 L ha�1 Nurille D 0.5 L ha�1

Suceava, Romania 47�380N, 26�150E April 8, 2009 2.5 400 Potato N 39 Ce-redin super 40SL 1 L ha�1 e

R. Redaelli et al. / Journal of Cereal Science 57 (2013) 193e199 195

300 samples; a further set of about 50 samples was randomlyselected for validation of NIRS prediction. The samples used weredivided into two lots, one for NIRS and the other for other analyses.Mathematical treatments (detrend, standard normal variance andfirst derivative) were applied.

2.5. Statistical analysis

Analysis of variance (ANOVA), Duncan’s test and determinationof the Pearson’s simple correlation coefficient r on the data fromthe standard cultivars set (11 and 7 varieties for total and soluble b-glucan, respectively) were performed with the MSTATC program(Michigan State University, East Lansing, US). Box plots and clusteranalyses were performed with MATLAB software (R2010a version,MathWorks Inc., USA). Hierarchical clustering was used to createrelatively homogenous groups of oat accessions using the followingtraits as criteria: total and soluble b-glucan and the soluble/totalpercentage.

3. Results and discussion

3.1. Screening of the working collection

Total b-glucan contentwas determined inmost of the accessionsharvested from three different locations every year; from the samefield trials a smaller set of genotypes was selected to represent asmuch as possible of the genetic variability of the working collectionand were characterized more in detail, by the quantification of thesoluble b-glucan fraction. The total and soluble b-glucan contentwas therefore determined in 647 and 154 accessions, respectively,in the two years. Different methods can be used for the analysis ofsoluble b-glucan and the extraction conditions may affect the yieldof soluble b-glucan. In this study the soluble b-glucan content wasestimated by the procedure suggested by Aman and Graham(1987), which used the extraction at body temperature (38 �C)and giving the maximum yield of soluble b-glucan after 2 h.

The accessions analysed belonged to 12 Avena species withdifferent ploidy levels. The genome classification, number ofaccessions analysed, range of variation in both total and soluble b-glucan and seed weights of each species are reported in Table 1.Avena sativa was the most represented species, followed by Avenastrigosa, Avena byzantina and Avena fatua. In A. sativa the valuesobserved ranged from 3.02 to 5.74% d.m. for total b-glucan andbetween 2.05 and 4.18% d.m. for the soluble fraction. The results fortotal b-glucan compared quite well with the values reported inprevious studies for different groups of genotypes (Cho and White,1993; Gajdosova et al., 2007; Lee et al., 1997; Peterson et al., 2005).

A. strigosa is marginally cultivated for feed; several accessions ofthis species were found to have high b-glucan contents, e.g. Ha 71e87 (RUS001 200111912, collected in Finland, 6.23% d.m.), Jari ZlatnaKisa (RUS001 200110392, collected in former Yugoslavia, 5.90%)and “Rauhhafer” (RUS001 200114678, collected in Belgium, 5.56%).This species also exhibited the widest range of variation for thisparameter. The mean b-glucan content in the accessions ofA. byzantina was 4.01% d.m., whereas in the A. fatua accessions themean value was 4.47% d.m. High b-glucan contents were also foundin accessions from the diploid wild species Avena damascena, Avenahirtula and Avena wiestii.

Among the A. sativa accessions, 39 were naked cultivated oats(A. sativa ssp. nudisativa). Naked oats can represent an importantraw material for food industry; therefore, their characterizationfrom the nutritional point of view was considered interesting. Inthis group of genotypes total b-glucan ranged from 3.02 to5.43% d.m.; the accessions with the highest contents were Platek(POL003 PL50731, 5.43%), a landrace of Greek origin (RUS001200111655, 5.29%), Vouti (SWE002 NGB360, 5.11%), Abel (CZE04703C0701716, 5.06%) and Litovskii Nagii (POL003 PL50910, 5.03%), allvalues being expressed on a dry matter basis (data not shown). Tenaccessions of naked oats were also characterized for soluble b-glucan, and showed a range of variation from 3.03 (Oskar) to3.76% d.m. (Woronezh). In this group, the soluble fraction repre-sented on average 82% of the total b-glucan (data not shown).

High b-glucan contents were found in some accessions of wildspecies, especially A. damascena, A. wiestii and A. hirtula (Table 1).This characteristic of uncultivated germplasm had already beenobserved previously. Among 30 Avena sterilis accessions analysedby Cho and White (1993), about one third had a total b-glucancontent higher than 5.5% d.m. Accessions of the diploid speciesAvena atlantica, A. hirtula and A. damascenawere also reported to berich in groat b-glucan (Miller et al., 1993; Welch et al., 2000), andboth interspecific and intraspecific variation being observed.

In the accessions analysed the seed weight appeared to berelated to the species and to the ploidy level and showed a wideintraspecific variability (Table 1). The superiority of modern culti-vars in seed weight reflects the focus of breeding programs toobtain large caryopses, a trait which is favourably considered by theindustry (Herrmann et al., 2012). However, no consistent relation-ship was found between b-glucan content and yield or seed weight.Statistically significant but weak correlations between b-glucanand yield or seed weight were found in only a few environments(data not shown).

When the soluble b-glucan was expressed as a percentage oftotal b-glucan, the values were found to range from 50.7 to 87.0%;this result was consistent with Aman and Graham (1987) which in

R. Redaelli et al. / Journal of Cereal Science 57 (2013) 193e199196

oat observed a range of values from 65.0 to 90.0%. As expected, totaland soluble b-glucanwere found to be highly correlated (r¼ 0.83**,n ¼ 165).

3.2. Hierarchical clustering of the accessions

Hierarchical clustering was used to create relatively homoge-nous groups of oat accessions using three variables, total andsoluble b-glucan and the soluble/total percentage, as classificationcriteria. Cluster analysis based on Euclidean distances separated154 oat genotypes into ten groups having two or more subgroups(Fig. 1); the cophenetic correlation coefficient of the cluster was0.8018. The table in Fig. 1 summarizes the oat accessions present ineach group and the mean values and ranges of variation for total b-glucan and the soluble/total percentage. The groups with thehighest mean values for total b-glucan (>6% d.m.) (groups 1, 6 and8) were composed of accessions belonging to the species A. strigosa,A. hirtula, A. fatua, A. wiestii and A. damascena. Groups 8 and 6 werealso characterized by high percentages of the soluble fraction, 80.3and 76.9%, respectively, whereas the A. strigosa accession in group 1(Ha 71e87, which was collected in 1974 in Finland) showed thelowest percentage of 50.7%. The single accession in group 8,combining very high content of b-glucan and a high percentage ofthe soluble fraction, belongs to A. hirtula and is held in the Polishgene bank (POL003 PL52214). The high b-glucan contents found inwild species suggests that they may be useful as sources of alleles

Fig. 1. Hierarchical clustering of 154 oat accessions characterized for both total and solubleaccessions clustered in each group are reported together with their corresponding mean v

for this trait in plant breeding; a similar conclusionwas reported byWelch et al. (2000). In the other groups of the cluster, in whichA. sativa accessions were predominant, the mean content of total b-glucan was rather similar, ranging from 3.97 to 4.31% d.m. On theother hand, the range of variation for the percentage of soluble b-glucan in the same groups was quite large, from 62.9% (group 2) to85.2% (group 5), suggesting that this percentage is predominant indetermining the clustering of the accessions.

3.3. Environmental and genetic effects

In the present study, the effects of genotype and environmenton b-glucan content were evaluated using the data obtained for thestandard cultivars harvested from five locations: Estonia andBulgaria in 2008, Sweden, France and Romania in 2009 (Table 2).Due to the different number of genotypes in which the content oftotal and soluble b-glucan was determined, the statistical analysesconsidered 11 standard cultivars for total b-glucan and sevencultivars for the soluble fraction.

The two locations used in 2008 showed quite opposite climaticcharacteristics. Bulgaria registered the highest mean temperatureduring the growing season and the lowest total rainfall (176 mm),whereas Estonia had the lowest mean temperature and a rainfall ashigh as 381 mm. The mean temperatures recorded in Romania andSweden 2009 were in the middle of these two extremes; rainfall inRomania was the highest of all locations, i.e. 397 mm, due to high

b-glucan (% d.m.), showing the ten groups obtained. In the left part of the figure, thealues and range of variation.

Table 3Analysis of variance for total and soluble b-glucan in the standard cultivars.

Total b-glucan Soluble b-glucan

DF Mean square DF Mean square

Location 4 0.859** 4 1.419**Error 12 0.04 12 0.06Genotype 10 2.075** 6 3.148**G � L 40 0.376** 24 0.190**Error 150 0.04 90 0.07

DF ¼ degrees of freedom; **p � 0.01.

R. Redaelli et al. / Journal of Cereal Science 57 (2013) 193e199 197

precipitation and storms in June 2009, whereas in Sweden the totalrainfall was 233 mm. Finally, in Clermont-Ferrand the season wasmild with 355 mm rainfall.

Analysis of variance was carried out with a split-plot model,with location as a main factor and genotype nested in it. The resultsare reported in Table 3. All the factors, i.e. location, genotype andtheir interaction, had statistically significant effects on both totaland soluble b-glucan, with genotype showing the major effect.

In Fig. 2 the five environments of the field trials are comparedgraphically using box plots, which show the median values of totaland soluble b-glucan and the variability observed in each locationfor the standard cultivars. A compressed box plot represented anenvironment inwhich amore uniform behaviour of oat varieties forb-glucan accumulation was observed; on the other hand, an elon-gated box plot such as Romania 2009 indicated a larger variabilityfor this trait. The comparison of the different environments by

Fig. 2. Box plots of total and soluble b-glucan (% d.m.) showing the variations in the five fieldof the box represents the median value; the box begins at the 25th percentile and ends adifferent from each other (p � 0.05). ARG ¼ Argentina; AUT ¼ Auteuil; BEL ¼ Belinda; EVMUR ¼ Mures; SAU ¼ Saul.

Duncan’s test suggested that, on average, the climatic conditions in2009 appeared to be more favourable for the accumulation of b-glucan in the cultivars analysed than in the previous year. In fact,the highest contents of both total and soluble b-glucan were foundin the samples grown in Romania (4.19e3.43% dm) and Sweden in2009 (4.03e3.35 % dm), and also in France for the soluble fraction(3.23% dm). The samples grown in Estonia and Bulgaria in 2008,on the other hand, showed lower contents of both total andsoluble b-glucan.

The role of the climatic factors in the accumulation of thiscompound in the cereal grain, in particular the effects of temper-atures and water availability during the growth season, have beenreviewed by Tiwari and Cummins (2009). In some studies, thereduced availability of water was found to be related to higher b-glucan contents (Brunner and Freed, 1994; Peterson, 1991).Doehlert et al. (2001) reported an opposite result, with the b-glucancontent appearing to be positively correlated to precipitation in Julyand August, and also correlated to warmer temperatures. From thedata of the present study, the interaction of genotype with theenvironment was found to be an important source of variability inb-glucan content; the environments inwhich b-glucan content washighest being characterized by a mild mean temperature and by anamount of rainfall regarded as sufficient for the different environ-ments (range from 233 to 397 mm).

The standard cultivars were quite well differentiated in terms ofboth total and soluble b-glucan (Fig. 2B). It was observed that Mina,Auteuil and Belinda had the highest content for both fractions. In

experiments (A) and in the standard cultivars (B). The line running through the middlet 75th percentile of data set. Different letters indicate that averages are significantlyO ¼ Evora; GEN ¼ Genziana; IVO ¼ Ivory; JAA ¼ Jaak; KRE ¼ Krezus; MIN ¼ Mina;

Table 4NIR statistics from calibration models for total and soluble b-glucan (% d.m.) inmilled oat groats.

Component N Mean Range of variation SD RSQ SECV

Total b-glucan 290 2.68 2.17e5.30 0.83 0.91 0.208Soluble b-glucan 302 3.65 1.23e4.18 0.72 0.79 0.234

N ¼ number of samples in calibration; SD ¼ standard deviation; RSQ ¼ coefficientsof determination for validation set; SECV ¼ standard error of cross validation.

R. Redaelli et al. / Journal of Cereal Science 57 (2013) 193e199198

addition toMina, other naked cultivars with high b-glucan contents(Platek, Vouti, Abel and Litovskii Nagi) are of potential interest foruse in food industry, as husked cultivars often have higher contentsof b-glucan than naked types (Givens et al., 2000; Redaelli et al.,2009).

3.4. Development of new calibrations for NIR analysis of total andsoluble b-glucan in oats

Several studies have demonstrated that NIR analysis can be usedfor the rapid analysis of chemical components in cereal grains. Asa high throughput method, Near Infrared Spectroscopy meets therequirements for breeding and facilitates selection based on traitswith potential health benefits, such as b-glucan content. Thepotential of NIR spectroscopy to predict dietary fibre componentshas been shown, for example, when NIRS and NITS technologieswere used to quantify soluble and insoluble dietary fibre in cereals(Blakeneyand Flinn, 2005; Kays andBarton, 2002; Salgo et al., 2010).NIRS was also used to determine the barley b-glucan content (de Sáand Palmer, 2006; Sohn et al., 2008) and, recently, Schmidt et al.(2009) have compared different types of NIR instruments for theirability to determine total b-glucan in naked barley. On the otherhand, in a previous paper we have shown the possibility of devel-oping a rapid, accurate and precise alternative method for thesimultaneous quantification of b-glucan and protein content innaked oat samples, based on the coupling of near-infrared spec-troscopy and chemometrics (Bellato et al., 2011). New calibrationswere developed here for NIR to accuratelymeasure total and solubleb-glucan in milled oat groat. To the best of our knowledge no workhas been published on the simultaneous measurement of total andsoluble b-glucan in oats by using NIR analysis.

A total of about 350 calibration and validation samples wereanalysed with the reference methods for total and insoluble b-glucan content, also determining the soluble fraction. The NIRcalibration statistics presented in Table 4 showed low standarderrors of cross-validation (0.208 and 0.234, respectively for totaland soluble b-glucan) and good coefficients of determination (0.91and 0.79, respectively for total and soluble b-glucan). The RPD (ratioof standard deviation to standard error of prediction) values (3.99and 3.07, respectively for total and soluble b-glucan) indicated thatthe two parameters could be rapidly estimated by NIRS withsatisfactory accuracy, allowing the selection of oats for these traits.

4. Conclusions

A large oat germplasm working collection, including manyspecies that had never been explored before, was grown in differentenvironments across Europe and characterized for contents of totaland soluble b-glucan. Due to the increasing interest in oats as a rawmaterial for food industry, the characterization of germplasm interms of potential health benefits is an important breeding target.In this study the existing range of variability in b-glucan wasdescribed, including the soluble fraction, a parameter that is notalways reported in the characterization of oat genotypes. Thischaracteristic has a large influence on health benefits and

technological properties of oat grain. Under the extraction condi-tions of this study, wide variation in the solubility of b-glucan dueto genotype and environment factors was observed. Statisticalanalyses (ANOVA) indicated that the genotype had amajor effect onb-glucan content and suggested that the most favourable condi-tions for its accumulation were found both in Romania, which alsopresented the widest variation, and in Sweden in 2009, withclimatic conditions regarded as normal for these environments andcharacterized by mild mean temperature and sufficient rainfallamounts during the period of vegetative growth. Hierarchicalclustering allowed the accessions to be clustered based on b-glucancontent and solubility, a trait which could affect significantly theirviscosity properties. Also, screening of the marginally cultivatedgenotypes and wild species identified new sources of geneticvariation that could be exploited to increase the accumulation of b-glucan. In particular, many accessions of A. strigosa, an oat specieswhich is marginally cultivated, had high percentages of total b-glucan. Finally, the development of NIRS calibrations to predict totaland soluble b-glucan means that the efficiency of breeding pro-grammes for these important traits can be increased.

Acknowledgements

This research was financed by the European project “Avenagenetic resources for quality in human consumption”. The projectwas co-funded by the European Commission (AGRI GENRES 061,council regulation 870/2004) with additional contributions byPeter Koelln KGaA, Elmshorn, Germany, Emco spol. s r. o., Prague,Czech Republic and Gemeinschaft zur Förderung der privatendeutschen Pflanzenzüchtung e.V., Bonn, Germany. The authorswish to thank the partners involved in the multiplication, de-hulling and milling of the selected accessions and in the determi-nation of the seed weight: Külli Annamaa, Jõgeva Plant BreedingInstitute, Estonia; Izabela Kordulasinska and Zofia Bulinska, IHAR,Radzików, Poland; Nadezhda Antonova, Institute of Plant GeneticResources “K. Malkov”, Sadovo, Bulgaria; Alf Ceplitis, SvalöfWeibullAB, Svalöv, Sweden; Jean Koenig and Gérard Branlard, INRA,Clermont-Ferrand, France; Danela Murariu, Vegetal GeneticResources Bank of Suceava, Romania; Matthias H. Herrmann, JuliusKühn Institute, Grob Lüsewitz, Germany.

Appendix A. Supplementary Material

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jcs.2012.09.003.

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