The objective of the study was to compare the nutritional value of three rye high-fibre products containing varying quantities of dietary fibre as well as their in vitro digestibility and fermentability. There were determined the major chemical component, with particular emphasis on the contents of DF and its components: arabinoxylans, β-glucans, and fructans, in a high-fibre product from milled rye, a wholemeal rye bread, and a bread containing 40 % of blend of high-fibre product and soluble fibre-rich fraction (produced while preparing the product). Also, the in vitro digestibility of starch and of some selected macronutrients was analyzed as was the in vitro fermentability of undigested DF components. It was found that the products analyzed significantly differed in their nutritional quality, especially in the content of dietary fibre and its components as well as in the content of assimilable saccharides including quickly assimilable starch. Moreover, it was determined that the three products significantly differed as regards the overall digestibility of nutrients contained in the dry matter thereof. The high-fibre product was characterized by the lowest digestibility value whereas the wholemeal rye bread – by the highest digestibility value. The in vitro experiments on colonic fermentability of undigested components of fibre showed that the response of fructans and β-glucans to the impact of colonic microflora was the strongest since all of them were fermented in all the products, while the arabinoxylans were the most resistant to the enzymatic activity of
faecal bacteria. Based on the in vitro experiments, the utilization degree was compared of the fibre and its components in human body; the utilization degree was calculated for three quantitatively different servings of the products studied, which fully covered the daily intake of the dietary fibre as recommended by EFSA. It was shown that both the fructans and the β-glucans contained in the products were fully utilized by human body, whereas the total dietary fibre and the arabinoxylans were utilized only partially.
high-fibre rye products, dietary fibre, bread enrichment, nutritional quality, in vitro digestibility, in vitro fermentability