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Study On Heat-induced Gelation Properties And Gel Forming Mechanism Of Myosin From Rabbit Skeletal Muscles

Posted on:2004-10-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:X L XuFull Text:PDF
GTID:1101360122493086Subject:Food Science
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Four main parts were involved in this thesis: (1) study of the extraction,purification and identification of myosin.and of myosin solution turbidity and solubility; (2) study of hardness.water holding capacity(WHC) and ultramicrostructure of heat-induced gelation of myosin; (3) study of rheological properties of myosin; (4) study of myosin gelling mechanism, and hypothesis of gelling mechanism was supposed.Chapter I Extraction, purification, identification and physicochemical properties of myosin from rabbit skeletal muscles: myosin was extracted, purified and identified from male rabbit(3 months old and had weight of 2~2.5kg) Pasoas major (PM) and Semimembranosus proprius (SMp) skeletal muscles. The rate of extraction was about 1% with about 20~30mg.ml-1 purified myosin. Four bands in the purified myosin showed in SDS-PAGE analysis, which were assigned to the myosin heavy chain (MHC) and light chains according to their relative molecular weight 205kDa, 25.9kDa, 17.8kDa and 13.8kDa, respectively.And molecular weight of the purified actin was about 40kDa.The absorbance at 340nm was used as the myosin solution turbidity and the rate of myosin concentrations before and after centrifugation as protein solubility. And effects of myosin concentration, pH, ionic strength, heating, phosphates and divalent metal ions, actin on solution turbidity and solubility of myosin were studied. The results showed that the effect of myosin concentration on turbidity was linear(R2=0.97). The turbidity reached its maximum at the pH5.5 in 0.6mol.L-1 KCl. The solubility increased significantly when the pH value was greater than pH 5.0. The turbidity increased and the solubility decreased with the decrease of the ionic strength. The turbidity increased with the increase of temperature, PM and SMp myosin turbidity reached the maximum at 55 C and 60 C(IS 0.6) respectively. The solubility decreased when the temperature increased. The addition of MgCl2 improved the turbidity and decreased the solubility, but CaCl2 improved both of them. In 0.6mol.L-1 KCl, the turbidity increased and solubility decreased with the increasing of SPP and TPP, but HMP got the opposite result, in 0.2 mol.L-1 KCl, TPP, SPP and HMP at low and high concentration had different effects on the turbidity and solubility of myosin. And myosin with actin had higher solution turbidity and lower solubility.Chapter II Hardness , water holding capacity and ultra microstructure of heat-induced gelation properties of myosin from rabbit skeletal muscles: effects of myosin concentration, pH, ionic strength, heating, phosphates, divalent metal ions, polysaccharides, TGase, non-meat proteins, actin on heat-induced gelation properties (Hardness, WHC and ultra microstructure) were studied. Results showed that gel Hardness and WHC increased with higher myosin concentration; the optimal pH forming the hardest gel was 6.0 for PM, 5.5 for SMp (IS 0.6), and was both 6.0 for WHC. At pH 6.0, the gel hardness enhanced with the increasing of ionic strength, had the peak at 1.0(PM) and 0.6(SMp). WHC of gels reached the maximum both at IS 0.2 and 1.0(not significantly different). Only PM myosin from pragram-heating formed harder gel than isothermal-heating, when heating time was 10 minutes. For PM and SMp myosins.the optimal temperature of gel was 70 癈.Program-heating gels had better WHC than isothermal-heating gels at all tempeiatures.but both had the maximum at 50 C. SPP and TPP decreased the gel hardness and PM gel WHC, but increased SMp gel WHC, while HMP improved the gel hardness and WHC. Gel hardness increased significantly with 10mmol.L-1 Mg2+ or 8mmol.L-1 Ca2+ for PM myosin and 12mmol.L-1 Mg2+ or 10mmol.L-1 Ca2+ for SMp myosin. Both Mg2+ and Ca2+ decreased gel WHC. Carrageenan had no effect on gel hardness and WHC. PM gel hardness increased with XG, 1.0%SA and 0.5%CMC-Na, only SA had decreasing effect on SMp gel hardness. XG, 0.5%CMC-Na and SA increased PM gel WHC, and SMp WHC increased only added with XG,0.5%CMC-Na and 1.0%SA. TGase increased gel hardness and WHC, and non-meat pr...
Keywords/Search Tags:Rabbit skeletal muscle, Myosin, Turbidity, Solubility, Hardness, WHC, Ultra microstructure, Rheological property
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