Effects of baking on dietary fibre, with emphasis on β-glucan and resistant starch, in barley breads

In this study, 50% sifted barley flour from six different varieties and 50% refined wheat flour was used to bake bread. The flour mixture and the bread crumb and crust were analysed for content and composition of total dietary fibre, arabinoxylan, fructan, β-glucan, starch and resistant starch. Total dietary fibre content and extractability were not changed significantly by bread making. The extractability of mixed-linkage (1 → 3), (1 → 4)- β-D-glucan (β-glucan) increased with baking, while the average molecular weight of β-glucan decreased. However in one variety, SLU 7, higher average molecular weight was maintained and a different pattern was apparent in the molecular weight distribution. SLU 7 is thereby promising for inclusion in bread where a higher molecular weight of β-glucan is preferred, especially since the content of β-glucan in SLU 7 is high. The resistant starch formed positively correlated with amylose content. The high amylose variety yielded 2.9% resistant starch in the bread crumb, making an important contribution to total dietary fibre.