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In recent years, the baking industry has focused its attention on substituting several chemical compounds with enzymes. Enzymes that hydrolyze nonstarch polysaccharides, such as xylanase, lead to the improvement of rheological properties of dough, loaf specific volume, and crumb firmness. The purpose of this study was to find a better solid-state fermentation substrate to produce high levels of xylanase and low levels of protease and amylase, which are enzymes involved in bread quality, from Thermoascus aurantiacus CBMAI 756. Wheat bran, corncob, and corn straw were used as energy sources. The enzyme extract of corncob showed high xylanase activity (130 U/mL) and low amylase and protease activity (<1 and 15 U/mL, respectively). This enzyme profile may be more profitable for the baking industry, because it results in a slower degradation of gluten. Our results confirm this finding, because the enzyme obtained by fermentation in corncob resulted in a gluten with a higher specific volume than all the other substrates that were tested. The crude xylanase presented maximum activity at a pH of 5, and the optimum temperature was 75 °C. It was stable up to 70 °C for an hour and at a pH range from 4 to 10.

The objective of this study was to evaluate the changes that occurred during processing white breads enriched with 5, 7.5, and 10% of medium-polymerized inulin (MPI). Farinographic analysis revealed that enrichment caused the development time and dough stability to increase by up to 69.9% and 62.8%, respectively, when 7.5% of MPI was incorporated into wheat flour. This indicated that the added MPI strengthened the doughs. Conversely, alveographic analysis demonstrated that MPI was harmful to the gluten network. The specific volume and humidity of breads with up to 7.5% MPI were similar to those of the control (MPI-free) bread. During bread storage for 10 days, we noticed that the retrogradation rate increased only for the bread sample with 10% MPI. However, MPI enrichment, regardless of concentration, promoted an increase in the Avrami exponent and affected bread firmness. Bread staling analysis indicated that the moisture difference between crumb and crust was higher for the MPI-enriched breads than for the control. Moreover, we prepared more consistent doughs and fresh breads with MPI contents of up to 7.5%, which presented good quality and were good fiber sources; however, we determined that inulin did not present an anti-staling effect.

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