Effect Of Different Treatments On The Quality Of Surimi And Crabmeat Mixed Gel

Silver carp?Hypophthalmichthys molitrix?,as one of the four major Chinese carps,has a huge yield and gradually become the main raw material of various surimi products.The occurrence of precocious Chinese mitten crab?E.sinensis?is a common phenomenon during farming.The precocious E.sinensis accounts for a large proportion of total amount,thus causing huge economic losses to the farmers.To the best of our knowledge,there are few studies on processing and utilization of precocious E.sinensis.In this paper,the effects of ultrasonic-assisted treatment combined with microwave heating,transglutaminase?TGase?,and three kinds of polysaccharide?maltodextrin,?-glucan,and konjac glucomannan?on the gel properties of surimi and crabmeat mixed gels were studied.The results could provide theoretical reference for the application of precocious E.sinensis to surimi products.The main conclusions are as follows:?1?Orthogonal experiment was designed to obtain the optimum conditions?crabmeat amount 5%;ultrasonic temperature 35?;ultrasonic time 60 min;ultrasonic power 210W;microwave power 5 W/g;microwave time 80 s;ultrasonic frequency 60 k Hz?of the ultrasonic and microwave treatment.And the result of verification experiment showed that the whiteness,hardness,chewiness and gumminess of the mixed gels under optimum conditions decreased,and the springiness,cohesiveness and resilience increased.However,the quality of the mixed gels after ultrasonic-assisted gelation or microwave heating alone was poor.?2?Compared with the traditional water bath heating,microwave heating significantly improved the deformation,but reduce the breaking force of the mixed gels.In addition,microwave heating promoted the aggregation of myosin heavy chains?MHC?and the formation of high molecular polymers,and improved the water holding capacity?WHC?.However,rapid heating rate of microwave would cause moisture loss and some spherical holes on gel surface.Microwave heating increased the?-helical content and decreased the?-sheet content,while the ultrasonic treatment and the addition of crabmeat had little effect on the secondary structure of gel protein.Crabmeat increased the WHC and increment of moisture content?IMC?of surimi gels and led to rough surface morphology,while ultrasonic treatment increased IMC and improved surface morphology.?3?The addition of crabmeat reduced the texture properties and affected the color of mixed gels.After the incorporation of TGase,the breaking force,deformation and the content of unfrozen bound water increased significantly.Crabmeat and TGase did not significantly affect the secondary structure of the mixed gel.But all gels containing TGase showed a denser protein network structure.These results indicated that crabmeat had a negative effect on the gel formation of surimi,while TGase could improve the gel properties of mixed gels.?4?Maltodextrin and?-glucan slightly improved the texture properties of the mixed gels.The addition of konjac glucomannan significantly reduced the breaking force and deformation of mixed gels,but improved WHC a lot.This may be due to that the relaxation time T₂₁,T₂₂,and T₂₃ shifted to lower values after the addition of konjac glucomannan,which means lower strength of moisture fluidity.Besides,a part of the immobile water transferred into free water and bound water.During the gel formation process,konjac glucomannan absorbed water and swelled,which made the immobile water in surimi gels combine with konjac glucomannan and resulted in the changes of texture properties and WHC in mixed gels.After the addition of maltodextrin and?-glucan,the curve of storage modulus?G'?in gelation temperature range?20-40??dropped relatively gently,while the curve changed a lot after addition of konjac glucomannan.This indicated that maltodextrin and?-glucan may reduce the degree of myosin denaturation in the initial stage of heating.