Effects of sugar beet fiber and guar gum on dough rheological properties and bread quality

The present study was carried out to study the effect of incorporation of fiber rich sugar beet fiber (Fibrex, F) and guar gum (GG) on dough rheology and bread quality. For this purpose, F was added into flour at different levels (3.0%, 6.0%, and 9.0%, w/w, flour basis). Besides the addition of F; GG (0.5%, 1.0% and 1.5%, w/w, flour basis) was added into the flour in order to improve dough rheological properties and bread qualities. F and GG blended flours were examined for rheological behaviour of dough by using Absograph-500 and Resistograph-500 instruments. After that, bread making qualities, both crust and crumb colors, textural and sensory properties of breads obtained from these blended flours were investigated. Incorporation of F and GG in flour altered the rheological properties of the dough. Water absorption, dough development time, dough stability, farinograph quality number increased with incorporation of F whereas GG addition mainly increased the water absorption value. Therefore, the combined use of F and GG increased the water absorption value more than when they were added seperately. Dough samples containing 6% F and 1.0% GG may be the highest addition levels to be added when all rheological parameters are evaluated together. Dough and bread weight increased, the specific volume generally decreased by the addition of F and GG, and it can be said that the most appropriate addition rates in terms of most of the bread making properties were 6 and 9% F and 1% GG. L* value of bread crust generally increased as the F addition increased, but decreased slightly as the GG addition increased (p<0.05). In general, there were no statistically significant difference in the b* value, hue, chroma, browning index and total color change value of the crust color of the breads at all addition rates (p>0.05). When the F addition level increased from 3% to 9%, L* value of bread crumb showed a tendency to decrease with increasing GG addition levels and there was significant difference in the L* value only at 9% F addition (p<0.05). According to the hardness values from TPA results, 6% F and 0.5% and 1.0% GG additions resulted more acceptable results compared to the values of the control bread. Although there were no major changes in sensory properties with the addition of F and GG to the bread formulation, the lowest scoring was detected in bread samples with 9% F and 1.5% GG addition. In general, while high amounts of F addition were found to be less acceptable, the tendency to decrease in acceptability values in sensory properties began to decrease with increasing GG addition. It has been concluded that 6% F and 0.5% and 1.0% GG can be used in bread production.