59D-19 |
Structural and emulsifying properties of ovalbumin-dextran conjugate |
S. J. CHOI1, H. J. Kim2, and T. W. Moon1. (1) Department of Food Science and Technology, School of Agricultural Biotechnology, Seoul National University, Seodun Dong 103, Kwonsun Gu, Suwon, 441-744, South Korea, (2) Research Center for New Bio-Materials in Agriculture, Seoul National University, Seodun Dong 103, Kwonsun Gu, Suwon, 441-744, South Korea One of the important functional properties of proteins that are relevant to food systems is emulsifying properties. Polysaccharide can stabilize the emulsion due to its viscosity. Ovalbumin possesses various functionalities and dextran shows high viscosity. Therefore, we hybridized ovalbumin and dextran to obtain conjugates with improved functionality. The objectives of this study were to investigate the binding pattern between ovalbumin and dextran and the structural and emulsifying properties of their conjugate. Ovalbumin-dextran conjugates were prepared through Maillard reaction with various reaction ratio. To purify the conjugates, ultrafiltration and gel permeation chromatography were conducted. The binding ratio of dextran to ovalbumin was determined by colorimetric methods, and weight-average molar mass values and root mean square radius of conjugates were measured using a multi-angle laser light scattering detector. The secondary and tertiary structures of the conjugates obtained by fluorescence spectroscopy and circular dichroism were compared with those of native ovalbumin. SDS-PAGE patterns revealed that dextran and ovalbumin were covalently attached to each other. Upto 2.5 moles of dextran appeared to bind with 1 mole of ovalbumin, resulting in the conjugate with maximum molar mass of around 70kDa. Upon binding with dextran, the secondary structure of ovalbumin seemed to be little changed. However, the states of side chain residues were changed by the attachment of dextran. Turbidimetric measurement of the ovalbumin-dextran conjugates showed that emulsifying properties of the conjugate were significantly improved as compared to ovalbumin, dextran, and ovalbumin-dextran mixture. The improvement in the emulsifying properties of ovalbumin was thought to be achieved by covalently linked dextran. These results suggest that two or Three moles of lysine residues in ovalbumin seemed to be susceptible to reaction with dextran. Increasing the hydrophilicity by conjugation with a neutral polysaccharide can be employed to improve the functionality of ovalbumin at the oil-water interface.
Session 59D, Food Chemistry: Proteins and Physicochemical Properties
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