Effects Of Different Phosphates On Functional Properties Of Myofibrillar Protein From Mantis Shrimp And Application

The effects of different phosphates on myofibrillar protein characteristics of mantis shrimp were studied and applied in meat products to enhance the market value of mantis shrimp.Based on the mantis shrimp as the research object,firstly the response surface methodology was employed to optimize conditions of phosphorylation of mantis shrimp myofibrillar protein.Then on the basis of the optimum conditions,the effects of KCl with different ionic strengths and polyphosphates on the structure,solubility and functional properties of myofibrillar proteins from mantis shrimps were studied.Finally,the effects of compound phosphates with different proportions on the quality of new type shrimp pie were investigated.The results were shown below:1.The optimal conditions for the phosphorylation of myofibrillar protein of mantis shrimp by polyphosphates were explored and the protein was used as the experimental material.The myofibrillar protein of mantis shrimp was phosphorylated with sodium tripolyphosphate(STP),sodium pyrophosphate(SPP)and sodium trimetaphosphate(STMP).The reaction pH,phosphate addition and reaction time were single factors.The response surface methodology was employed to determine optimum conditions of phosphorylation of mantis shrimp myofibrillar protein.The results showed that the optimum conditions of STP were: reaction pH 8.0,phosphate addition 4% and reaction time2.0 h.Under these conditions,the degree of phosphorylation was 102.87 mg/g,which was1.38% different from the theoretical value(101.47 mg/g).The optimal process of SPP were:reaction pH 7.5,phosphate addition 2%,reaction time 2.0 ? h,and the degree of phosphorylation was 96.41 ? mg/g,which was 0.66% different from the theoretical value(96.07 mg/g).The optimum conditions of STMP were as follows: reaction pH 8.0,phosphate addition 4%,reaction time 2.5?h,and the degree of phosphorylation was 76.53?mg/g,which was 1.48% different from the theoretical value(77.68 mg/g).The obtained model had a good fit and the optimization result was reliable.2.Using myofibrillar protein from mantis shrimp as experimental material,the effects of different ionic strengths of KCl(0~0.05 mol/L)with polyphosphates on the tryptophan fluorescence,solubility,gel properties(viscosity,storage modulus,loss modulus,strength,hardness,elasticity,whiteness and water holding capacity),emulsifying properties(emulsifying activity,emulsion stability and creaming index)of the protein were studied.The results showed that compared with natural myofibrillar protein,the fluorescence intensity of STP phosphorylated protein decreased and the structure expanded,while the fluorescence intensity of SPP or STMP phosphorylated protein increased similarly.The solubility,gel properties(except whiteness),emulsifying properties of STP or SPPphosphorylated protein increased significantly(P<0.05).The solubility and gel properties of STMP phosphorylated protein increased significantly(P<0.05).The emulsifying activity did not change much,the viscosity and emulsion stability decreased,but creaming index increased.Generally speaking,polyphosphates altered the structure of myofibrillar protein of mantis shrimp,and improved the solubility and functional properties of the proteins to a certain extent.Compared with the sample group of 0 mol/L,after adding KCl,the fluorescence intensity of STP phosphorylated protein first increased and then decreased with the increase of KCl ionic strength.The solubility,gel properties and emulsifying properties of the protein also showed the same trend.The result was most effective when the ionic strength was 0.03 mol/L.With KCl ionic strength increased,the fluorescence intensity of SPP phosphorylated protein also decreased first,then increased and decreased last.Except that there was no significant change in gel elasticity and whiteness(P>0.05),other properties were further improved,and the properties was the best when the ionic strength was 0.03mol/L.The fluorescence intensity of STMP phosphorylated protein decreased first and then gradually increased with the change of ionic strength,and the solubility and functional properties of phosphorylated protein were improved,reaching the best at 0.05 mol/L.It was concluded that there was a synergistic effect between KCl and polyphosphates,and the combination of KCl and polyphosphates could further improve the properties of myofibrillar proteins.3.Mantis shrimp was used as the test material to explore the influence of different proportions of composite phosphates(STP:SPP:STMP=1:1:1,1:2:2,2:1:2 and 2:2:1)on the quality of new shrimp pies.The results showed that compared with the control group without phosphate,four groups of different proportion of compound phosphate shrimp pies could reduced the cooking loss and ascorbic acid content during processing(P<0.05),and improve the texture characteristics.In particular,the effects on the hardness and chewiness content of shrimp pies were the most obvious,and sensory score also was increased,but compound phosphates had little effect on the color and smell.In addition,when the proportion of STP:SPP:STMP was 2:1:2,the quality of mantis shrimp meat products was significantly improved(P<0.05).