ABSTRACT
The goal was to assess the effects of partial replacement of wholemeal rye flour with 30%, 40% and 50% of the high-fibre rye flour (HFRF) on nutritional quality and sensory and physicochemical characteristics of breads. The HFRF supplemented breads (SB30, SB40, SB50) were compared in their nutrients and energy contents, physicochemical and sensory properties, and in vitro digestibility to the control bread (CB). There were no significant differences in shape and volume of loaves, crusts and crumbs appearance, taste and smell of two supplemented breads (SB30 and SB40) and the CB. Compared to the CB, all supplemented breads contained significantly more soluble and insoluble fibre, arabinoxylan and ß-glucan, but less available saccharides, including rapidly available glucose. Bread with 40% HFRF (SB40) yielded both, improved nutritional quality and acceptable sensory characteristics comparable to the CB. An in vitro overall digestibility of the SB40 was lower than that of the CB but the losses of dietary fibre and its components after enzymatic digestion were comparable between both breads. In conclusion, rye bread supplemented with 40% of the HFRF had improved nutritional quality and acceptable sensory and physicochemical characteristics and could be considered as an option to commonly consumed wholemeal rye bread.
ABSTRACT
BACKGROUND: Many studies have demonstrated the potential health benefits of consuming more high-fibre cereal-based food products. Therefore, there is a need to discover new ways to improve the overall nutritional balance of refined cereal products and focus on increasing their dietary fibre content, at the expense of readily digestible carbohydrates. METHODS: Lab-scale milling and sieving of whole rye grain was used to obtain two fractions rich in dietary fibre. The fractions were analysed and compared, in terms of microstructure, chemical com- position and nutritional quality. RESULTS: The two fractions significantly obtained differed in their particle size and contents of minerals, available saccharides, and nutritional fractions of starch and dietary fibre and its major components. The total dietary fibre concentrations in the coarse and fine fractions were 50.0 and 36.0 g/100 g, respectively, i.e. three and 2.2 times higher than that of wholegrain rye flour. Both fractions also differed in their relative proportions of major fibre components. In the fine fraction, the levels of soluble fibre, as well as soluble arabinoxylans and fructans, were significantly higher than those in the coarse fraction. CONCLUSIONS: It was shown that the application of a simple dry-fractionation method to wholemeal rye flour allows the preparation of two rye products which can serve as concentrated sources of dietary fibre low in available saccharides.
