Protein solubility of Pacific whiting muscle with isoelectric point at pH 5.5 was
significantly affected by pH. The highest breaking force was measured from fish
proteins treated at pH 11, while high deformation values were obtained at pH 2 and
11. Texture of gels made using the conventional method were quite inferior to gels
made using fish proteins treated at pH 2 or 11, while color of conventional gels was
significantly better than the other treatments. SDS-PAGE revealed that fish proteins
were highly denatured during acid or alkali treatment. High cathepsin B-like
activity was detected from acid-aided fish proteins. Strong cathepsin L-like activity
was found in fish proteins treated at pH 10.5, which corresponded with the lower
breaking force and deformation obtained from those samples. Disulfide bonds contributed to high texture value in fish proteins treated at pH 11.
Physicochemical characteristics of sarcoplasmic proteins (SP) from rockfish
and their interaction with Alaska pollock surimi (myofibrillar proteins) were
investigated. Solubility of SP was significantly suppressed at acidic pH (2-4) plus
high salt concentration (0.5 M NaCl). This was also supported by SDS-PAGE
results (extensively degraded SP). DSC results revealed SP gave three endothermic
transitions. The least amount ofproteins was lost when treated at pH 2 or 3 followed
by precipitation at pH 5.5. SP did not enhance the gelation properties of myofibrillar
proteins, but positively contributed to gelation with myofibrillar proteins when
compared to sucrose. Myofibrillar proteins were primary components contributing
to heat-induced gelation.
Salt effect on acid- or alkali-treated surimi gel was investigated. Good gels
were obtained without salt using acid- and alkali-treated fish proteins. Their texture
properties decreased as NaCl content increased, unlike conventional surimi gels.
Consequently, NaCl did not solubilize myofibrillar proteins once the fish proteins
were treated by acid or alkali. Solubility was apparently not a key factor for the
texture properties of acid- or alkali-treated surimi. Transglutaminase-mediated
setting reaction was partially inactivated during acid or alkaline treatment.
Acid-treated surimi gel gave the best color properties. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27189 |
| Date | 13 December 2002 |
| Creators | Kim, Young S. |
| Contributors | Park, Jae W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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