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Role of Hydrogen Peroxide Produced by Baker's Yeast on Dough Rheology¹

¹Contribution 98-40-J. Kansas Agricultural Experiment Station, Manhattan. ²Graduate research assistant, research associate, and professor, respectively, Dept. Grain Science and Industry, Kansas State University, Manhattan, 66506. ³Present address: Bunge Foods, 725 North Kinzie Ave., Bradley, IL 60915. ⁴Present address: R&R Research Services, Inc., 8831 Quail Lane, Manhattan, KS 66502. ⁵Corresponding Author, e-mail: r_and_r@kansas.net

Baker's yeast, Saccharomyces cerevisiae, has a well-known effect on dough rheology during breadmaking. During a 3-hr fermentation, hydrogen peroxide (H₂O₂) produced by yeast (0.76%, fwb) increased from 1.09 to 2.32 μmol/g of flour. The spread test, a measure of a dough's rheological properties, showed that yeast had an effect on dough rheology similar to that of H₂O₂, an oxidant that makes flour-water dough more elastic. In additional experiments (spread test and H₂O₂ measurement), glucose oxidase, an enzyme that produces H₂O₂, gave results similar to those with yeast. The fact that catalase, an enzyme that destroys H₂O₂, reversed the rheological effect of added H₂O₂ but did not reverse the effect of either yeast or glucose oxidase suggested that either wheat flour contains an inhibitor to catalase or H₂O₂ was not the active component. A series of experiments, including use of defatted flour, remixing, and mixing dough under nitrogen, all indicated that catalase was inhibited by peroxides in the lipid fraction of flour. These results also suggested that H₂O₂ is responsible for the effects of yeast and glucose oxidase on dough.