Effect Of Amino Acids On The Thermal Aggregation Of Myosin From Bighead Carp(Aristichthys Nobilis)

The surimi and surimi products are protein gel preparations by heat denaturation of fish protein,especially myosin.The surimi products have developed rapidly because of their high protein,low fat,high nutrition and good taste.China’s annual consumption of surimi products has been more than one million tons.With the increasing scarcity of marine fish resources,the status of freshwater fish as a substitute has been gradually increased,among of which,the huge silver carp has been successfully developed into freshwater surimi.However,traditional surimi products such as fish cake,Fish Tofu,imitation crab meat,fish sausage and so on have the same characteristics like high elasticity and high hardness,which are more favored by young people,but not suitable for the elderly,children and others.With the aging of the increasingly serious society,the development of surimi products with high protein,low calorie,easy to eat is becoming more and more important.Amino acid is a small molecule food component that has been used in the fields of nutritious food and medicine.It has been reported that L-Arg can prevent protein aggregation and change the rheological properties of the gel,but the specific mechanism has not been elucidated.In this study,the effect of L-Lys,L-Arg or L-His on the thermal aggregation behavior of myosin from bighead carp at different heating treatments were studied in order to provide a theoretical basis for new surimi products geared to the needs of the elderly,patients,children and other groups.Main contents and conclusions are as follows:1.Effects of amino acids on physicochemical properties of bighead carp myosin under different heat treatments.The effects of different amino acids on myosin were measured by high sensitivity Zeta potential and particle size analyzer,UV / Vis spectrophotometer and fluorescence spectrophotometer.Particle size,turbidity and surface hydrophobicity were measured.The turbidity and particle size of the myosin without amino acid increased significantly as the temperature increased and the time was prolonged.L-Lys,L-Arg and L-His could reduce the turbidity and particle size of myosin under setting(heatingat 40 °C for 60 min)and two-stage heating(at 90 °C for 30 min after 40 °C for 60 min)and change the surface hydrophobicity.2.Effects of amino acids on secondary structure of bighead carp myosin under different heat treatments.The effects of different amino acids on the secondary structure of myosin were studied by circular dichroism and Raman spectroscopy.The results showed that circular dichroism is suitable for the study of the effect of L-Lys or L-Arg on the secondary structure of myosin at a concentration of not more than 10 mM.Raman spectroscopy is suitable for the effect of L-Arg or L-His on the secondary structure.L-Lys and L-Arg can promote the development of myosin,the α-helix content decreased significantly,and the higher the L-Lys or L-Arg concentration,the lower the α-helix content.L-Lys reduced the α-helix content of myosin under non-heating,setting and second-stage heating from 91.26% to 35.39%,from 67.33% to 30.8%,and from 61.55% to 18.64% respectively.L-Arg decreased the α-helix content of myosin from 99.07% to 24.26%,from 92.52% to 23.92%,and from 65.98% to 7.79%respectively.L-His can slow the unfoling of myosin in the heated state.3.Effects of amino acids on and gelaion properties and gel strength of bighead carp myosin under different heat treatments.The effects of different amino acids on the G’ key,gel rate,elastic modulus(G’),loss tangent(tan δ)and gel strength of myosin-amino acids mixed gels were studied by dynamic rheometer and property meter.The results showed that L-Lys,L-Arg and L-His were able to decrease the denaturation temperature,gel rate,gel formation ability and gel strength of myosin,and effects of L-His were weaker than L-Lys and L-Arg.In addition,5 mM L-Lys and L-Arg were sufficient to minimize the rate of gelation and breaking of myosin.In the range of added concentration,the gelation rate and break force decreased with the increasing concentration of L-His.The results showed that L-Lys,L-Arg and L-His could affect the relationship between development rate and aggregation rate of myosin by electrostatic interaction,changing the pH value and occupying the hydrophobic binding site.As a result,L-Lys,L-Arg and L-His could inhibit the thermal aggregation of myosin.Meanwhile,theinhibitory degree was different due to the different charges and structures of the three amino acids.The effect of L-His was weaker than that of L-Lys and L-Arg.