Quantification and visualization of dietary fibre components in spelt and wheat kernels

• Wheat is richer in cellulose and hemicellulose than spelt, lignin content is similar.
• Wheat is richer in arabinoxylan and fructan than spelt.
• The β-glucan content of spelt and wheat is similar.
• Arabinoxylans and β-glucans were microscopically visualized in spelt and wheat kernels.
• Stained kernel sections of the two subspecies looked rather similar.

This study was undertaken to determine contents and structural characteristics of arabinoxylan (AX), fructan and β-glucan in 28 spelt accessions, and to compare them with those of dietary fibre components in 11 wheat accessions. In addition, microscopic visualization of AX and β-glucan distribution in a selection of these accessions was performed. On average, wheat contained more total AX (TOT-AX; 6.90 versus 5.74%) and water-extractable AX (WE-AX; 0.71 versus 0.59%) than spelt. The overall arabinose to xylose ratio (A/X; 0.72 for wheat and 0.71 for spelt) was similar for both subspecies, but that of water extractable material was higher for spelt than for wheat (1.25 versus 0.97). Fructan content and degree of polymerization (DP) were lower in spelt than in wheat (fructan content; 1.29% versus 1.53% and DP; 3.3 versus 4.5). β-glucan content was similar for both subspecies (0.54% for spelt and 0.51% for wheat). In the spelt accessions, the contents of the different fibre components significantly differed (up to 74% difference) between accessions and countries of origin, but were not affected by accession status and bread making quality. Microscopic visualizations showed that the two subspecies are very similar in terms of dietary fibre distribution over the kernel cell walls.