Variation in the degree of D-xylose substitution in water-extractable European durum wheat (Triticum durum desf.) semolina arabinoxylans.
Durum wheat (Triticum durum Desf.) semolina water-extractable arabinoxylan (TWEAX) (yield 0.28%, arabinose-to-xylose ratio (A/X) 0. 62) was fractionated by a stepwise increase in ethanol concentration (up to 65%). The A/X ratios of the resulting fractions varied between 0.42 and 0.80. With increasing ethanol concentrations, increasing A/X ratios went hand in hand with a relative increase of low molecular weight compounds, indicating that high molecular weight compounds with a low A/X ratio are preferentially precipitated from alcohol/water mixtures. (1)H NMR showed that, whereas in TWEAX the levels of unsubstituted xyloses (X(0)), monosubstituted (X(1)), and disubstituted (X(2)) xyloses were 63.1%, 11.8%, and 25.1%, respectively, fractions that precipitated with increasing ethanol concentrations had decreasing levels of X(0). Simultaneously, the level of X(1) decreased equally until it leveled of at ca. 10%. Concomitantly, the level of X(2) increased. The levels of X(0), X(1), and X(2) varied between 69.7% and 53.4%, 18.2% and 10.7%, and 12.2% and 35.9%, respectively.
Roels
S P
SP
Laboratory of Food Chemistry and Center for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Heverlee, Belgium.
Collado
M
M
Loosveld
A M
AM
Grobet
P J
PJ
Delcour
J A
JA
D001089:Arabinose / Q000032:analysis; D002850:Chromatography, Gel; D005060:Europe; D005433:Flour / Q000032:analysis; D014908:Triticum / Q000737:chemistry*; D014990:Xylans / Q000737:chemistry*; D014994:Xylose / Q000032:analysis*
D014990:Xylans; C085118:arabinoxylan; D014994:Xylose; D001089:Arabinose