Submitted to: Food Hydrocolloids Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2014
Publication Date: 4/13/2014
Citation: Kokubun, S., Yadav, M.P., Moreau, R.A., Williams, P.A. 2014. Components responsible for the emulsification properties of corn fibre gum. Food Hydrocolloids Journal. 41:164-168. Interpretive Summary: “Corn fiber gum” (CFG) is a potential high value food ingredient we have prepared from “corn fiber”, an abundant and inexpensive byproduct of the corn wet milling ethanol process. This new product has potential uses and high value because it has been shown to be a better emulsifier (compound that helps suspend oil in water) than gum arabic, an expensive and imported “gold standard” emulsifier used in the food industries. Gum Arabic is a “glycoprotein” that contains water loving (hydrophilic) polysaccharide and water-hating (hydrophobic) protein components on the same molecule, allowing it to interact with both oils and water which is required for good emulsifier activity. CFG has previously been shown to be primarily a hydrophilic polysaccharide. The scientific community has therefore wondered how such a polysaccharide could function as an emulsifier. Our research was done to find the components responsible for this interesting emulsifying property of this polysaccharide and solve this puzzling problem. First we made the emulsion of oil with CFG and spun it at very high speed to separate oil and water layer. The separated oil layer was further treated with surfactant which separated the CFG coated on the oil droplets. Upon collection and analysis of this CFG, we discovered that it was very rich in protein. This new finding explains how a hydrophilic (water-loving) polysaccharide like corn fiber gum, can act as an emulsifier and associate with oils. It is because of the hydrophobic character imparted by the presence of protein. This information will be useful to scientists and manufacturers who are endeavoring to produce and market CFG as a gum arabic substitute. These results may benefit corn farmers because new uses for corn byproducts will ultimately improve market for corn. It will also benefit the U.S. consumer and the U. S. economy since home-grown corn fiber gum containing this important protein can substitute for imported gum arabic in food products.
Technical Abstract: An emulsion was prepared using corn fibre gum (CFG) and the resulting oil and aqueous phases were separated by centrifugation. The material adsorbed onto the surface of the oil droplets in the oil phase was desorbed using surfactant. The desorbed CFG and the non adsorbed CFG that remained present in the aqueous phase were collected, precipitated using alcohol and freeze dried. Their sugar composition, phenolic acid, lipid and protein contents were determined. There was no consistent difference observed in the sugar composition, phenolic acid and lipid contents of the original material and the adsorbed and non adsorbed fractions. There was, however, a significant difference in the protein contents with the adsorbed fraction containing ~10.7% protein compared to 3.90% and 2.87% for the original and non adsorbed CFG samples respectively. The three samples were also found to have very similar molecular mass distributions and each showed the presence of two peaks using refractive index detection. The major peak, corresponding to ~95% of the total, had a molecular mass of ~ 650,000 g/mol and the minor peak corresponded to a molecular mass of ~ 90,000 g/mol. The corresponding UV elution profiles indicated that the minor peak contained a significant proportion of phenolic and/or proteinaceous material.