Antioxidant properties of cookies supplemented with sugar beet dietary fibre

Abstract

The antioxidant properties of cookies prepared by the addition of sugar beet fibre were investigated in order to provide data for new functional food formulation. Treated fibre (TF) was obtained from sugar beet by extraction with sulphurous acid (75 °C and pH 5.7 during 60 min). It was dried (80 °C), ground and sieved. The fraction with the particle size less than 150 μm was used for further investigations in comparison to commercially available Fibrex. Cookies were prepared by the addition of 0, 7, 9 and 11% of sugar beet fibre as a substitute for wheat flour in cookies' formulation. The antioxidant properties of cookies were tested every 7 days by DPPH radical scavenging test during 6 weeks of storage at room temperature (23±1 °C) and expressed as IC50 value (mg/ml). IC50 value was defined as the concentration of an antioxidant extract which was required to quench 50% of the initial DPPH{bullet operator} under the experimental conditions given. The IC50 values of cookies with TF were lower in comparison to those obtained for control cookies. Furthermore, concentration of added fibre and IC50 was strongly correlated. Higher concentration of TF in cookies assured their better antioxidant properties. The IC50 values of cookies with TF followed the same trend during storage as the control cookies. The significant increase was observed after the first week of storage, followed by the decrease and successive increase until the end of the experiment. The best IC50 values, i.e. the lowest, were obtained for the cookies with Fibrex and those values were also dose-dependent. The comparison of IC50 values of cookies with different concentrations of fibre pointed out that there are significant differences (P<0.05) between all cookies with added TF, but only between 7% and 11% of Fibrex-incorporated cookies from the third to the sixth week. Better antioxidant capacities of cookies prepared by the addition of sugar beet fibre could be attributed to the presence of phenolic compounds in sugar beet, especially ferulic acid. © Wageningen Academic Publishers The Netherlands, 2010.