Effect Of Amino Acid On The Formation And Mechanism Of Heat-induced Gel Of Tilapia Myosin

Gel properties is one of the most important features of fish myosin.The properties of heat-induced gelation played a decisive role in aquatic protein products,which can improve the texture quality of products and had a good taste.However,the low solubility and poor gel properties of myosin at low salt conditions limit the processing and utilization of myosin.Myosin was used as raw material in this experiment.Investigate the gel formation and its mechanism of heat-induced myosin gelation under different ionic strength.The influence of ionic strength on solubility,turbidity and structure during heating was discussed,and also discussed the formation mechanism of gel under low strength conditions.The purpose of this study is to provide the theoretical basis for the production practice of low salt aquatic protein food.The main results were as follows:(1)Under the same concentration condition,effects of ionic strength(1~600mmol/L NaCl)on the turbidity,solubility,surface hydrophobicity,sulfhydryl content and molecular morphology of heat-induced myosin gelation were studied.And then discussed the formation mechanism of heat-induced myosin gel.Under high ionic strength(600 mmol/L NaCl)condition,the solubility of myosin increased and the turbidity decreased.With the increase of heat treatment temperature(20~80?),the solubility of myosin decreased gradually,turbidity and surface hydrophobicity increased significantly(p<0.05),the total sulfhydryl content decreased significantly under different ionic strength condition.At the same time myosin denatured and aggregated.With the increase of temperature,the interaction between myosin intermolecular enhanced,and the elastic modulus value of myosin also increased.At low ionic strength,there were many holes in the gel,and the surface of myosin gelation was uneven,which lead to disordered and instable three-dimensional network structure.While under high ionic strength conditions,the gel had a uniform and smooth structure,which caused ordered three-dimensional network structure,and the stability was good.(2)Select of four kinds of ionic strength(1,50,150,600 mmol/L NaCl),and then studied the effect and mechanism of arginine(_L-arginine,Arg)on the formation of myosin heat-induced gel.The solubility,surface hydrophobicity and total sulfhydryl content of myosin at low ionic strength(1,50 mmol/L)was significantly increased after dialysis with5 mmol/L_L-arginine(_L-Arg)solution.(p<0.05).Myosin became longer,shorter,and thicker Under high ionic strength(600 mmol/L NaCl)conditions,the solubility and molecular morphology of myosin did not change obviously.The addition of_L-Arg inhibited the aggregation of myosin during heating,increased the solubility and the surface hydrophobicity.And also increased the G?value of myosin under low ionic strength conditions.Formed an opaque gel with smooth surface and uniform pore size,and the chemical interaction of the gel was dominated by hydrophobic interaction.The arginine improved the three-dimensional structure of myosin gel at low ionic strength conditions and the structure was stable.The gel mechanism of myosin at low ionic strength with arginine may be related to the surface hydrophobicity and molecular morphology.(3)The solubility,surface hydrophobicity and total sulfhydryl content of myosin at low ionic strength(1,50 mmol/L)and physiological ionic strength(150 mmol/L NaCl)conditions was significantly increased after dialysis with 5 mmol/L_L-lysine.But the effect of lysine on the solubility and molecular structure of the myosin was not obvious under high ionic strength(600 mmol/L NaCl)conditions.The addition of_L-Lys inhibited the aggregation of myosin during heating,increased the solubility and the surface hydrophobicity.And also increased the G?value of myosin under low ionic strength conditions.Formed a flat surface structure with uniform size.The hydrophobic interaction is the main force maintain the gel.The three-dimensional network structure of myosin gel became more stable at high ionic strength conditions.The gel mechanism of myosin at low ionic strength with lysine may be related to the surface hydrophobicity and molecular morphology.(4)In order to improve the gel properties of myosin under low ionic strength condition,the effect and mechanism of amino acid on the heated-induced gel from-carrageenan and myosin mixture were investigated.The results showed that when-carrageenan was added,the elastic modulus and water holding capacity of-carrageenan and myosin mixture significantly increased,and a uniform and ordered three-dimensional structure was observed at low ionic strength.At high ionic strength the three-dimensional network structure of-carrageenan and myosin mixture were more stable after dialysis with_L-arginine and_L-lysine,the whiteness and gel strength of-carrageenan and myosin mixture were significantly increased,and the microstructure of the composite system was improved.Formed the dense and uniform three-dimensional structure,and the hydrophobic interaction and disulfide covalent bond were the main factors to maintain the chemical interaction of the gel,which strengthened the gel structure of the composite system.Compared to the addition of carrageenan,the gel properties of-carrageenan and myosin mixture are better with the amino acids.