Dielectric Study of Heat-Denatured Ovalbumin in Aqueous Solution by Time Domain Reflectometry Method
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- 作者：Yuanxia Sun ; Tomoyuki Ishida ; and Shigeru Hayakawa
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2004
- 出版时间：April 21, 2004
- 年：2004
- 卷：52
- 期：8
- 页码：2351 - 2357
- 全文大小：90K
- 年卷期：v.52,no.8(April 21, 2004)
- ISSN：1520-5118
文摘
The dielectric behavior of native and heat-denatured ovalbumins (OVAs) from three avian species inaqueous solution was examined over a frequency range of 100 kHz to 20 GHz, using the time domainreflectometry (TDR) method. For the native OVA solutions, three kinds of relaxation processes wereobserved at around 10 MHz, 100 MHz, and 20 GHz, respectively; these could be assigned to theoverall rotation of protein molecules, the reorientations of the bound water, and the free watermolecules, respectively. For the heat-denatured samples, three relaxation processes were alsoobserved. However, the relaxation process at ~100 MHz originated via a different mechanism otherthan the reorientation of bound water, namely, the micro-Brownian motion of peptide chains of heat-denatured protein. From the observed relaxation process at ~100 MHz, the relaxation strength ofheat-denatured OVA solution for duck was higher than that of OVA solutions for hen and guinea fowland showed the pH dependency from pH 7.0 to 8.0 for OVAs obtained from all three species.Furthermore, the results demonstrated that the relaxation strength was closely related to surfacehydrophobicity of protein molecules and gel rheological properties. It was suggested that the differencein the surface hydrophobicity of protein influenced the dielectric behavior of water around denaturedprotein, whereas the dielectric behavior of denatured protein could be an indication of the gelrheological properties. Such studies can aid in the understanding of the different network structuresof OVA gels from three avian species.Keywords: Ovalbumin; dielectric relaxation; gelation; rheological properties; time domain reflectometry