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Importance of Protein-Rich Components in Emulsifying Properties of Corn Fiber Gum

¹Crops Conversion Science and Engineering Research Unit, Eastern Regional Research Center, Agricultural Research Service, USDA, 600 East 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. ²Corresponding author. Phone: 215 836-3783. Fax: 215 233-6559. E-mail address: madhav.yadav@ars.usda.gov

Purified corn fiber gum (CFG-F) isolated from fine (kernel endosperm-derived) corn fiber that contained ≈2% residual protein was extracted with 70% aqueous ethanol. The aqueous ethanol extract (AEE), which contained 19.5% of the total CFG, contained a high percentage of the proteinaceous material present in the original gum sample. The AEE gum contained 6.81% protein by weight. The residue (R), which constituted 66% of the total CFG-F, contained only 0.55% of protein. The emulsifying properties of R and AEE in a model oil-in-water emulsification system were studied by measuring turbidity after 1, 2, and 3 weeks, particle size after 4 weeks, and by confocal laser scanning microscopy after three months of storage at room temperature. These gums were compared with the standard well-known emulsifiers native acacia gum (NAG) and modified acacia gum (MAG). The results indicate that although AEE contains protein-rich components, it is not as good an emulsifier as the residue which contains only 0.55% of protein. However, emulsions prepared with the whole (unfractionated) CFG-F under similar conditions were more stable showing higher turbidity and smaller particles size than those prepared with either R or AEE.