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Effect of Zinc and Aluminum Ions in Breadmaking1

May 1999 Volume 76 Number 3
Pages 355 — 360
Keswara Rao Vadlamani 2 and Paul A. Seib 2 , 3

Contribution 98-204 of the Kansas Agricultural Experiment Station, Manhattan, KS 66506. Graduate research assistant and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. Corresponding author. E-mail: pas@wheat.ksu.edu

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Accepted January 8, 1999.

Zinc and aluminum ions as chloride or sulfate salts at 50–500 ppm metal ion (flour basis) had no detrimental effect on fermentation of yeastleavened dough. Increased mixing times (≈10–50%) due to addition of aqueous solutions of zinc (250–500 ppm) or aluminum (150–250 ppm) ions to a bread formula was overcome by withholding salt until the final mixing stage. Breads made from commercial flours (12.5% protein) containing zinc (250–500 ppm) or aluminum (150–250 ppm) ions and no oxidant had improved loaf volume and crumb grain when compared with control bread, and no off-taste. Additionally, breads with added zinc or aluminum had better crumb grains and slower firming rates when compared with breads containing optimum L-ascorbic acid (50 ppm) or potassium bromate (20 ppm). Breads made from commercial flours (11.1% protein) and three laboratory flours (11.4–13.6% protein) containing zinc (250 ppm) or aluminum (150 ppm) ions also had improved loaf volumes and crumb grains. Zinc or aluminum ions in combination with L-ascorbic acid, but not potassium bromate, had a detrimental effect on bread quality. Scanning electron microscopy of freeze-dried bread doughs revealed that zinc and aluminum ions enhanced the film-coating property of gluten. One serving (one slice, 28 g) of bread made with 250 ppm zinc ion would provide 25% of the adult recommended dietary allowance of zinc.

© 1999 American Association of Cereal Chemists, Inc.