Submitted to: Food Hydrocolloids Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2013
Publication Date: 11/13/2013
Citation: Cirre, J., Al-Assaf, S., Phillips, G.O., Yadav, M.P., Hicks, K.B. 2013. Improved emulsification performance of corn fiber gum following maturation treatment. Food Hydrocolloids, 35:122-128. Interpretive Summary: The need to add value to corn milling by-products has prompted us to prepare corn fiber gum (CFG) and change it into a superior flavor stabilizer (emulsifier). Corn fiber is obtained from corn dry milling and corn wet milling industries. It 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 contains a lower amount of 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. To increase the flavor stabilizing capacity of CFG obtained from corn milling processes, a simple heating treatment (maturation process) without adding any chemical was applied. The maturation process re-distributes (re-orients) the embedded protein of CFG, which makes it more hydrophobic due to bringing the hydrophobic protein to the surface. Thus the hydrophobic protein on the surface becomes fully available for coating oil droplets during stabilizing process of flavoring oil. This redistribution of protein present in CFG on heat treatment makes it a far superior flavor stabilizer than the untreated CFG. This process is a simple and economical food grade heating technique. It just re-orients the protein present on CFG to convert it into a better flavor stabilizer for e.g. a soft drink system. These findings will benefit U. S. corn processors by adding value and creating additional markets 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 milling by-products will also indirectly help to reduce overall cost of fuel ethanol produced from corn kernels.
Technical Abstract: Corn fiber gum (CFG) in the solid state (milled powder form) was subjected to a maturation treatment by heating under atmospheric pressure at 110 degrees C for 5 (CFG5) and 24 hours (CFG24). The treatment reduced the solubility and aggregation of the proteinaceous component with increased heating time. The protein content of CFG is comparable to that of gum arabic but has a different amino acids profile. Glutamine and proline are the most abundant in CFG compared with hydroxyproline and serine in gum arabic. The control and matured CFG samples have been characterized by gel permeation chromatography coupled on line to a multi angle laser light, refractive index and UV detectors. The weight average molecular values for control, CFG5 and CFG24 were 4.2, 5.8 and 5.7 x 105 g/mol respectively with corresponding Rg values of 29, 44 and 41 nm. High pressure homogenization treatment of the control gum did not show significant changes whereas the matured samples were disaggregated. The emulsification performance and stability of the matured samples were greatly improved in comparison with the control gum. A three fold increase in the proportion of the fraction adsorbed onto the oil water interface accounts for the improved emulsification. A model to describe the changes following maturation and the improved emulsion stability is proposed based on the result for our laboratory.