Submitted to: Carbohydrate Polymers
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2010
Publication Date: 3/7/2010
Citation: Yadav, M.P., Parris, N., Johnston, D., Onwulata, C.I., Hicks, K.B. 2010. Corn fiber gum and milk protein conjugates with improved emulsion stability. Carbohydrate Polymers. 81:476-483. Interpretive Summary: The need to add value to corn dry milling by-products has prompted us to prepare corn fiber gum (CFG) and change it into a better flavor stabilizer. Corn bran/fiber obtained from corn dry milling and corn wet milling industries, is an abundant low value material used for animal feed. Corn fiber (corn bran) produced by the corn dry milling process comes mostly from the pericarp portion of corn kernel and so also can be called corn pericarp fiber. As it originates only from corn pericarp, it contains very little protein. Corn fiber produced by the corn wet milling process comes from both the pericarp and endosperm portion of corn kernel and so it contains higher amount of protein. We have found that protein deficient CFG derived from corn bran from corn dry milling process is an inferior flavor stabilizer to the protein rich CFG obtained from corn fiber from the corn wet milling industry. To increase the flavor stabilizing capacity of CFG obtained from dry milling corn fiber, whey protein, a low value by-product of cheese processing was added to CFG with dry heating process to increase its oil flavor binding capacity. This process is a simple and economical technique to introduce protein onto CFG for converting it into a better flavor stabilizer for a soft drink system. These findings will benefit U. S. corn and cheese processors by adding value and creating additional market for their by-products. It will also benefit U. S. manufacturers of CFG who will be able to produce a constant supply of improved quality corn fiber gum emulsifiers at reasonable prices. The generation and recovery of additional valuable product from corn dry milling by-products will also indirectly help to reduce overall cost of fuel ethanol produced from corn kernels.
Technical Abstract: Corn fiber gum (CFG), an alkaline hydrogen peroxide extract of the corn kernel milling by-product “corn fiber” was covalently conjugated with Beta-lactoglobulin (Beta-LG) and whey protein isolate (WPI). Covalent coupling of CFG to protein was achieved by dry heating reaction (Maillard-type) of CFG and protein mixtures (3:1) for up to 7 days at 75 deg.C and 79% relative humidity. The formation of the CFG and protein conjugate was confirmed by SDS-polyacrylamide gel electrophoresis. The conjugates as well as pure proteins and pure CFG were compared for their ability to stabilize oil-in-water emulsions by both turbidometric and Dynamic Light Scattering (DLS) methods. Measurements of turbidities, particles size distribution and average particle size in emulsions have shown that CFG-protein conjugates prepared by dry heating at 75 deg.C and 79% relative humidity for up to 2 days were more effective at stabilizing emulsions at room temperature than was CFG or protein alone.