Publication no. C-1998-0601-03R |  VIEW ARTICLE

An Improved Process for Isolation of Corn Fiber Gum.

Landis W. Doner (1,2), Hoa K. Chau (1), Marshall L. Fishman (1), and Kevin B. Hicks (1). (1) U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. (2) Corresponding author. E-mail: <ldoner@arserrc.gov> Cereal Chem. 75(4):408-411. Accepted March 3, 1998. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1998.

Sequential alkaline extraction and alkaline hydrogen peroxide (AHP) bleaching have been used to prepare corn fiber gum in yields ranging from 21 to 40%, depending on the pH of the extraction medium. The pH was adjusted by using different ratios of NaOH and Ca(OH)(2). The whitest product was obtained after AHP bleaching of the extract obtained using the lowest pH value. In order for the product gum to give its characteristic clear and low viscosity solutions, it was necessary to remove starch from the corn fiber substrate using alpha-amylase. The water-insoluble hemicellulose A fraction, a minor component, was removed by neutralizing AHP-treated extracts before ethanol precipitation of the useful hemicellulose B (corn fiber gum) fraction. At ambient temperature, AHP bleaching was near optimal after approximately 2 hr under the processing conditions used. High ratios of arabinose (39%) to xylose (50%) were present in the corn fiber gum extracted under various alkaline conditions, and the H(2)O(2) processing step did not significantly alter these ratios. The same low levels of galactose (7%) and glucuronic acid (4%) were present regardless of the extraction conditions. Molecular mass of the corn fiber gum preparations ranged from 2.78 × 10(^5) for the material extracted with Ca(OH)(2) to 3.94 × 10(^5) for the material extracted with NaOH. Molecular mass was unaffected by the H(2)O(2) present in the second processing step. As expected for a carbohydrate polymer with a rather low uronic acid content, solution viscosities were unaffected by the presence of salt.