Effects Of L-Histidine On Physico-Chemical And Heat-Induced Gelation Properties Of Myosin From Rabbit Psoas Muscle

Myosin is the major protein in meat, making up about1/3in muscle protein, accounting for50%to55%of the myofibrillar protein. Myosin has a good three-dimensional gel structure forming ability, which contributes to textural properties, shaping products, retaining water, and holding other food components in products. Myosin is considered to be dissolved only in the high salt solution, which limits myosin processing properties, nor conducive to the production and R&D of low sodium gel-type meat products. L-Histidine is a semi-essential amino acid, myosin solubility can be increased at low ionic strength by L-histidine treatment. This research took rabbit psoas muscle as material, studied the effect of L-histidine on physico-chemical and heat-induced gelation properties of myosin. The results of the research stated as follows:1. Effect of L-histidine on myosin solubility, turbidity and microstructureEffects of L-histidine on myosin solubility at different ionic strength were investigated. The results showed that myosin solubility was low at low ionic strength (0.OOlmol/L KCl), but more than60%of myosin solubilized in the presence of L-histidine. No significant changes was observed of myosin solubility in the presence of L-histidine at physiological (0.15mol/L KCl) or high ionic strength (0.6mol/L KCl). Myosin solubility did not change significantly by ultrasonic treatment. Myosin turbidity at physiological ionic strength was high than that at low or high ionic strength. Turbidity of myosin decreased significantly at low ionic strength in the presence of L-histidine. But no significant changes were found at physiological or high ionic strength. Under conditions of low ionic strength and physiological ionic strength, myosin formed crystal-like structure in the absence of L-histidine, but myosin filaments dispersed in the presence of L-histidine. Myosin dispersed into monomer at high ionic strength. These results indicated that L-histidine treatment can significantly increase myosin solubility, reduce turbidity at low ionic strength; myosin filaments dispersed in the presence of L-histidine at low or physiological ionic strength.2. Effect of L-histidine on the bio-chemical properties and heat-induced gel properties of myosinEffects of L-histidine on myosin solution surface hydrophobicity, sulfhydryl content, disulfide bonds content, rheological properties, chemical interactions, solubility of myosin gels and heat-induced gel properties at different ionic strength conditions were investigated. The results showed that under conditions of low ionic and physiological ionic strength, myosin hydrophobic and disulfide content significantly increased in the presence of L-histidine, the reactive sulfhydryl content and total sulfhydryl content decreased significantly. At high ionic strength, hydrophobic and disulfide content had no significant changes in the presence of L-histidine, but the reactive sulfhydryl content and total sulfhydryl content decreased significantly. Myosin storage modulus increased significantly in the presence of L-histidine at low ionic strength and the initial value of the phase angle8reduced at different ionic strength. The content of hydrogen bonds and ionic bonds reduced, hydrophobic interactions increased significantly at different ionic strength by L-histidine treatment. The solubility of myosin gels at different ionic strength reduced significantly at different ionic strength by L-histidine treatment. Myosin gel hardness at high ionic strength was the highest. Gel hardness at low ionic strength increased significantly in the presence of L-histidine, but at physiological or high ionic strength, their gel hardness decreased. Water holding capacity(WHC) of myosin at low ionic strength increased significantly in the presence of L-histidine. WHC of myosin gels at high ionic strength decreased significantly, but at physiological ionic strength, no significant changes were found. These results indicate that L-histidine treatment at different ionic strength had different effects on myosin solution surface hydrophobicity, sulfhydryl content, disulfide bonds content, rheological properties and chemical interactions, solubility, heat-induced gel properties of myosin gels.