VALUE ADDED COPRODUCTS FOR IMPROVING THE ECONOMICS AND GREENHOUSE GAS EMISSIONS OF CORN AND CELLULOSIC FUEL ETHANOL PRODUCTION
Location: Sustainable Biofuels and Co-Products
Title: The development of a new corn fiber gum isolation process that preserves its functional components
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 27, 2011
Publication Date: September 3, 2011
Citation: Yadav, M.P., Moreau, R.A., Hotchkiss, A.T., Hicks, K.B. 2011. The development of a new corn fiber gum isolation process that preserves its functional components. Carbohydrate Polymers. 87:1169-1175.
Previous studies in our lab have reported a method to produce a potentially useful food additive called Corn Fiber Gum (CFG). In this case, the word “gum” does not mean that this material would be used as a chewing “gum”, but rather as a food ingredient composed of complex carbohydrates that can serve as an emulsifier. This useful gum was made in our lab from corn fiber, a low-value by product of the industrial wet milling of corn. CFG was shown to be a better emulsifier than gum Arabic, a “gold standard” emulsifier, and was shown to have several other potential industrial applications. It was also found that protein associated with CFG was key for its emulsifying properties. Lipids and phenolic acids are well known for emulsion stabilizing and antioxidant activities respectively. The importance of these three unique components prompted us to develop conditions for making functional CFG which will preserve a high percent of its associated protein, lipid and phenolic acids. In this current study we found for the first time that these functional components may be preserved in high percent, if CFG is isolated by boiling corn fiber for a short time at low alkali concentration. Food industries will be benefitted by using such CFG which will help to reduce its usage levels in beverage and significantly decrease the cost of soft drink production. In this way it will increase the value of corn milling by-products benefiting U.S. corn processors and corn farmers. In addition, if this compound is commercialized, it will become a coproduct from fuel ethanol production and will help to reduce the cost of fuel ethanol prepared from corn kernels using the wet milling process.
Corn fiber gum (CFG) is a hemicellulose (arabinoxylan)-enriched fraction obtained by the extraction of corn bran/fiber using a mild alkaline hydrogen peroxide process. The unique polysaccharide, CFG, with its low solution viscosity has been proposed as a stabilizer for oil-in-water emulsions. We have verified that in some model systems, CFG can out-perform the "gold standard" emulsifier, gum arabic. Our results have also shown that "pure" CFG fractions often contain considerable amounts of associated lipids, phenolic acids and proteins which contribute to its emulsifying properties. The extraction of CFG with alkaline hydrogen peroxide was investigated using different combinations of alkali concentration and time to identify the optimum extraction condition to retain its functional groups (protein, lipids and phenolic acids). The pure CFG prepared by this process was hydrolyzed with 1.5 N methanolic KOH at 70 °C for one hour to release hydroxycinnamic acids (p-coumaric and ferulic) and lipids. The total lipid was extracted with chloroform/methanol, evaporated and quantified. The released phenolic acids were identified and quantified using HPLC with detection by both UV and evaporative light-scattering detection (ELSD). The protein content was determined by an AACC approved combustion method. The total lipids, phenolic acids and protein content in CFGs isolated with lower alkali concentration for a shorter time was comparatively higher than CFGs isolated with higher alkali concentration for a longer time. The presence of these phenolic acids, lipids and protein in CFG may contribute to its excellent emulsifying properties and may combine to give improved chemical, physical, and even nutritional properties. Understanding these critical structural elements required for optimal emulsification properties will allow future commercial producers of CFG to provide consistent quality and functionality in their products.