Submitted to: Food Hydrocolloids Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 6, 2006
Publication Date: June 1, 2007
Citation: Yadav, M.P., Johnston, D., Hotchkiss, A.T., Hicks, K.B. 2007. Corn fiber: a potential gum arabic replacer for beverage flavor emulsification. Food Hydrocolloids 21, p.1022-1030. Interpretive Summary: The U. S. beverage industry uses hundreds of tons of high quality emulsifiers each year for stabilizing citrus oil flavor in soft drinks. The most commonly used emulsifier, “gum arabic” is an imported gum that is expensive and is often in short supply due to political and environmental issues in the African countries of origin. To solve this problem, we previously extracted and purified a new type of “gum” called “corn fiber gum (CFG)” from an abundant and inexpensive byproduct of corn processing called “corn fiber”. We have now analyzed the chemical structure of CFG and found it to be primarily a polysaccharide. Polysaccharides, like starch and cellulose, are not known for their ability to act as emulsifiers; however, our studies on CFG show it to be an excellent emulsifier, equal to or better than gum arabic. We therefore did additional studies to determine how CFG could exhibit this unusual and commercially useful property. First we prepared CFGs from corn fiber produced from different corn milling processes. We then tested their ability to emulsify citrus oil in water and also analyzed their chemical composition. We found that some CFG samples contained small amounts of protein and that these samples tended to be the best emulsifiers. CFG with a higher protein content was a better flavor stabilizer than CFG with a lower protein content. This is a completely new finding. We are now doing additional research to determine the nature of the protein components to completely understand and better control CFG’s emulsifying ability. These results will benefit corn farmers because finding new uses for corn byproducts will ultimately improve markets for corn. They will also benefit U.S. consumers and the U.S. economy since “home grown” corn fiber gum can substitute for a strategic material (gum Arabic) that must now be imported.
Technical Abstract: The U.S. food industry needs a domestically produced food gum with a dependable supply and consistent quality, which can be used for preparing oil-in-water emulsions, such as citrus oil emulsions for beverages. Corn Fiber Gum (CFG) is an arabinoxylan (hemicellulose) extracted from the corn kernel pericarp and/or endosperm fiber fractions that can possibly fulfill this need. CFG-1 was prepared from corn fiber collected from different wet or dry corn milling facilities by extraction with alkali followed by alkaline hydrogen peroxide bleaching of the extracted gum. CFG-2 was prepared from the residue of the CFG 1 extracts by a one-step alkaline hydrogen peroxide extraction. CFG-1 might be linked to the cell wall matrix through ester linkages and CFG-2 by non-ester linkages and/or other strong interactions. The stabilization of oil-in-water emulsions by corn fiber and acacia gums was investigated by preparing emulsions with high-pressure homogenization and monitoring the emulsion breakage by turbidity measurements. CFG-2 extracted from three different corn fiber sources was determined to be a better emulsifier than their corresponding CFG-1. CFGs isolated from wet milled pericarp and endosperm fiber (WPEF) and wet milled pericarp fiber (WPF) have a higher protein content than CFGs isolated from dry milled pericarp fiber (DPF) and were determined to be better emulsifiers for the oil-in-water emulsion system. The emulsifying properties of all CFGs including an industrial grade commercial CFG were determined to be better than native and modified acacia gums.