Carbohydrate Polymers 90 (2012) 1226–1234 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers j ourna l ho me pag e: www.elsevier.com/locate/carbpol Enzymatic fingerprinting of arabinoxylan and -glucan in triticale, barley and tritordeum grains A. Rakha a,c,∗,1 , L. Saulnier b , P. Åman a , R. Andersson a a Department of Food Science, Swedish University of Agricultural Sciences, P.O. Box 7051, SE-750 07 Uppsala, Sweden b INRA UR1268 Biopolymers, Interactions Assemblies, 44316 Nantes, France c National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan a r t i c l e i n f o Article history: Received 9 January 2012 Received in revised form 20 June 2012 Accepted 21 June 2012 Available online 29 June 2012 Keywords: Triticale Barley Tritordeum Arabinoxylan -Glucan Enzymatic fingerprinting a b s t r a c t Enzymatic fingerprinting of arabinoxylan (AX) and -glucan using endo-xylanase and lichenase, respec- tively, helps determine the structural heterogeneity between different cereals and within genotypes of the same cereal. This study characterised the structural features of AX and -glucan in whole grains of eight triticale cultivars grown at two locations, 20 barley cultivars/lines with wide variation in compo- sition and morphology and five tritordeum breeding lines. Principal component analysis (PCA) resulted in clear clustering of these cereals. In general, barley and tritordeum had a higher relative proportion of highly branched arabinoxylan oligosaccharides (AXOS) than triticale. Subsequent analysis of triticale revealed two clusters based on growing region along principal component (PC) 1, while PC2 explained the genetic variability and was based on mono-substitution and di-substitution in AX fragments. PCA of -glucan features separated the three cereals based on -glucan content. The molar ratio of trisaccharide to tetrasaccharide was 2.5–3.4 in triticale, 2.3–3.3 in barley and 2.8–3.4 in tritordeum. Barley showed a strong positive correlation (r = 0.86) between -glucan content and relative proportion of trisaccharide. The results show that structural features of AX and -glucan vary between and within triticale, barley and tritordeum grains which might be important determinants of end-use quality of grains. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Cell walls of cereal starchy endosperm and aleurone are rich in polysaccharides, particularly arabinoxylan (AX) and mixed link- age (1→3) (1→4)--d-glucan (-glucan), where these polymers act as structural components (Cui & Wang, 2009; Fincher & Stone, 1986; Stone, 2006), but may also have metabolic activity related to cell function and development (Cosgrove, 1993). AX dom- inates in the endosperm cell walls of most cereals (60–70%), with the exception of oats and barley (≈20%) (Fincher & Stone, 1986; Matz, 1991). The backbone of AX consists of (1→4)-linked Abbreviations: AX, arabinoxylan; A/X, arabinose/xylose; X, xylose; XX, xylo- biose; AXOS, arabinoxylan oligosaccharides; -glucan, (1→3) (1→4)--D-glucan; BGC, -glucan content; BGE, -glucan extractability; GOS, gluco-oligosaccharides; BG3, 3-O--cellobiosyl-d-glucose; BG4, 3-O--cellotriosyl-d-glucose; BG5, 3-O- -cellotetraosyl-d-glucose; BG6, 3-O- cellopentaosyl-d-glucose; HPAEC, high performance anion exchange chromatography; PCA, principal component analysis. ∗ Corresponding author at: Department of Food Science, Swedish University of Agricultural Sciences, Box 7051, S-750 07 Uppsala, Sweden. Tel.: +46 18672063; fax: +46 18672995. E-mail address: Allah.Rakha@slu.se (A. Rakha). 1 Permanent address: National Institute of Food Science and Technology, Univer- sity of Agriculture Faisalabad, Pakistan. Tel.: +92 41 9201105; fax: +92 333 9201439. -d-xylopyranosyl residues, which can be either mono-substituted by -l-arabinofuranosyl residues at the O-2 or O-3 position or di-substituted at O-2 and O-3. Mono-substitution by -l- arabinofuranosyl residues at O-2 is very rare in wheat and rye but frequent in barley (Izydorczyk & Dexter, 2008; Izydorczyk, Macri, & MacGregor, 1998a; Saulnier & Quemener, 2009; Viëtor, Angelino, & Voragen, 1992). Variation in degree and pattern of substitution by -l-arabinofuranosyl residues along the xylan backbone and degree of polymerisation (DP) of the xylan backbone are impor- tant structural features of rye AX and contribute to structural heterogeneity and physico-chemical properties (Vinkx & Delcour, 1996). For example, AX with decreasing -l-arabinofuranosyl residues become less soluble due to the formation of aggregates (Andrewartha, Phillips, & Stone, 1979). The structural features of wheat flour AX may also determine the end-use quality of cereals, since wheat flour with a higher proportion of di-substitution has good bread-making properties (Cleemput, Roels, Van Oort, Grobet, & Delcour, 1993). Furthermore, the extent of substitution controls the action of hydrolytic enzymes and highly branched AX molecules are less prone to enzymatic degradation (Vinkx & Delcour, 1996). Since the endo-xylanase action is dependent on the structure of AX, the hydrolysis products can be used to explore structural diversity between and within different cereals or their botanical parts. 0144-8617/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.carbpol.2012.06.054