博士 / 國立中興大學 / 食品科學系 / 90 / Tilapia was used to investigate the gelation mechanism of fish proteins. Results showed that the properties of pressure- and heat-induced gels were different from the protein denaturation mechanisms. Pressure-induced (≧200 MPa) gels, constructed by ionic and hydrogen bonds, hydrophobic interactions and disulfide bonds, were soft, viscous and similar color to the meat paste. Heat-induced (50℃) gels, constructed by ionic and disulfide bonds, hydrophobic interactions and GL bonds, were hard, elastic and in white color. The stronger strength of gels induced by pressure or heat were obtained by the treatment at 200 MPa and 50℃, respectively. We combined the two treatments (200 MPa→50℃) and got the strongest gel strength which stabilized by all the bonds induced by pressure and heat. However, the properties of gels formed by the treatment at 50℃ and followed by 200 MPa were similar to those only by heat. On the other hand, the gels formed by 200 MPa at 50℃ were very viscous owing to the inhibition of protein denaturation. Therefore, pressure could help viscous properties of gels due to the non-covalent bonds, and the following heat treatment helped maintain the original bonds and constructed the covalent-bonding structures of gels with elastic properties.
Physical and chemical properties of myosin and S-1 changed by pressure treatment (50-300 MPa/4℃), but those of rod did not. Myosin and S-1 molecules occurred apparently aggregation by pressure treatment at 150 and 200 MPa, respectively, due to the different pressure sensitivity on molecular weight. The pressure-induced gelation mechanism of tilapia myosin is as follows: myosin head decreases its volume and forms intramolecular interactions by pressure treatment behind 100 MPa; when pressure increases to 150-200 MPa, hydrophobic groups and reactive sulfhydryl groups of S-1 exposure outward, then myosin forms elastic gels by disulfide bonds and hydrophobic interactions owing to S-1 aggregation.
Due to the analysis of inactivation kinetics of myosin and S-1 Ca-ATPase, the denaturation level of myosin and S-1 decreased 90% of D value with each increase of 185 and 806 MPa, respectively, without considering IPK. Therefore, pressure-induced denaturation of myosin depended on IPK, pressure level and duration, however, that of S-1 depended on IPK and pressure level only.
| Identifer | oai:union.ndltd.org:TW/090NCHU0253005 |
| Date | January 2002 |
| Creators | Kuo Chiang, Hsu, 徐國強 |
| Contributors | Wen Ching, Ko, 柯文慶 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 163 |
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