title: Production of crude xylanase from Thermoascus aurantiacus CBMAI 756 aiming the baking process.
abstract: 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.
authors.affiliation: UNESP, Sao Paulo State Univ., Lab. of Biochemistry and Applied Microbiology, Rua Cristovao Colombo, 2265-Sao Jose do Rio Preto, Sao Paulo, CEP 15054-000, Brazil.
authors.forename: Denise S
authors.initials: DS
authors.lastname: Oliveira
authors.forename: Carolina
authors.initials: C
authors.lastname: Meherb-Dini
authors.forename: Célia M L
authors.initials: CM
authors.lastname: Franco
authors.forename: Eleni
authors.initials: E
authors.lastname: Gomes
authors.forename: Roberto
authors.initials: R
authors.lastname: Da-Silva
mesh_terms: D001939:Bread / Q000032:analysis; D055598:Chemical Phenomena; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D004795:Enzyme Stability; D005285:Fermentation; D005503:Food Additives / Q000378:metabolism*; D005524:Food Technology; D005656:Fungal Proteins / Q000378:metabolism*; D005983:Glutens / Q000032:analysis; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010447:Peptide Hydrolases / Q000378:metabolism; D011786:Quality Control; D055327:Thermoascus / Q000201:enzymology* / Q000378:metabolism; D013997:Time Factors; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D005503:Food Additives; D005656:Fungal Proteins; D005983:Glutens; D000516:alpha-Amylases; D043364:Endo-1,4-beta Xylanases; D010447:Peptide Hydrolases