Peroxidase-mediated formation of corn fiber gum-bovine serum albumin conjugates: molecular and structural characterization

Authors: LIU, YAN - China Agricultural University; Yadav, Madhav; Chau, Hoa - Rose; YIN, LIJUN - China Agricultural University

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2017
Publication Date: 2/27/2017
Citation: Liu, Y., Yadav, M.P., Chau, H.K., Yin, L. 2017. Peroxidase-mediated formation of corn fiber gum-bovine serum albumin conjugates: molecular and structural characterization. Carbohydrate Polymers. 166:114-122.

Interpretive Summary: Corn fiber gum (CFG) is a good flavor stabilizer for beverages and food. This study was undertaken to test the hypothesis that binding additional protein to CFG would further improve its flavor stabilizing properties. Corn bran/fiber is obtained from corn dry or wet milling industries. It is an abundant low value material used for animal feed. We have found that CFG, deficient in protein, is an inferior flavor stabilizer in comparison to protein rich CFG. To increase the flavor stabilizing capacity of protein deficient CFG, a commercial protein was attached to it by using an enzyme. Bovine serum albumin (BSA), a readily available commercial protein, has the appropriate structure to bind with CFG. So this protein was reacted with CFG in the presence of an enzyme (horseradish peroxidase) to form their conjugate. The formation of CFG and protein conjugate was fully confirmed by gel electrophoresis, microscopic and molecular mass (size) studies. This enzyme treatment process is a simple food grade technique to introduce protein onto CFG for converting it into a better flavor stabilizer for a soft drinks and other food applications. These findings will benefit U. S. corn processors by adding value and creating an 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 milling by-products will also indirectly help to reduce overall cost of fuel ethanol produced from corn kernels.

Technical Abstract: Corn fiber gum (CFG) is a good flavor stabilizer for beverages and food. This study was undertaken to test the hypothesis that binding additional protein to CFG would further improve its flavor stabilizing properties. Conjugates of corn fiber gum (CFG) and bovine serum albumin (BFG) were prepared in a reaction mixture containing 0.125% ~ 5% CFG, 2% BSA, and H2O2, catalyzed by horseradish peroxidase. The molecular weight of CFG and BSA mixtures (10:1 and 4:1) increased from 200 and 193 kDa to 218 and 223 kDa respectively, when treated with horseradish peroxidase. With higher concentration of CFG present, more tyrosine residues were consumed but it didn’t lead to higher conjugation degree as shown by multi-angle laser light scattering photometer that no higher molecular weight conjugates were present. Scanning electron microscopy revealed that peroxidase crosslinked CFG-BSA mixtures had a more compact and rougher surface morphology as compared with the uncrosslinked. But the microstructure of CFG-BSA conjugates with different CFG concentrations didn’t show marked distinctions. However, particles of CFG-BSA conjugates made from low concentration of CFG (0.125%) were elongated while conjugates made from high concentration of CFG (5%) had spherical particles when observed with transmission electron microscopy.