The results of SDS-PAGE and densitometry indicated that a significant amount
of myofibrillar proteins was lost during surimi processing. Microfiltration (MF) was
utilized to recover insoluble particulate. The MF-recovered proteins showed highly
functional properties in gel hardness, cohesiveness, color, and water retention ability. The
soluble proteins concentrated by ultrafiltration (UF) possessed dark colors and strong
odors. However, the use of UF demonstrated the possibility of recycling water in
leaching systems.
To reduce the loss of myofibrillar proteins during processing, the factors causing
solubilization of myofibrillar proteins were investigated. Myosin and actin were highly
soluble when their ionic strengths were substantially reduced. Salt concentrations of
0.25%, 0.5%, and 1.0% NaCl reduced the solubility of myosin and actin but did not
remove sarcoplasmic proteins effectively. At 2.0% NaCl, severe loss of myosin, actin,
α-tropomyosin, β-tropomyosin, and troponin-T was observed. At low water/meat ratio
(2:1) with increased washing cycles and washing time, more sarcoplasmic proteins per unit of water were removed without a noticeable loss of myosin or actin. Myosin heavy
chain (MHC) content, water retention ability, and whiteness of the washed mince were
comparable to that at high water/meat ratio (4:1). Prolonged storage and elevated
temperatures caused a severe proteolysis of myofibrillar proteins. The degraded proteins
had higher solubility than their native myofibrillar proteins. MHC and actin degradation
both showed a good correlation to protein solubility.
The relationship between conformational changes and solubility of myofibrillar
proteins was investigated using myosin as a model system. The results showed that
adding salt or shifting pH from the isoelectric point of myosin caused an increased
surface hydrophobicity and a decreased helix structure. A slightly increased sulfhydryl
content was also observed. These conformational changes resulted in an increased
solubility. At high salt concentration (>1.0 M), myosin regained its helix structure with
a concomitant loss of solubility. The salting out effect was probably due to the dominant
hydrophobic interaction among nonpolar amino acids residues. / Graduation date: 1996 / Best scan available. Original is a black and white photocopy.
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28170 |
| Date | 07 March 1996 |
| Creators | Lin, Tein Min, 1964- |
| Contributors | Park, Jae W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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