Interaction Of Chicken And Soy Proteins Catalyzed By Enzyme

The subject is based on high-quality resources of white feather broiler in Fujian Province,and studied the reaction induced by transglutaminase which took place between chickenand soy proteins. Moreover, the relationship between the reaction and the protein’sproperties,such as gelation and emulsification,which directly affect the quality of theproducts, had been investigated, too.This study lay the theoretical foundation and providethe necessary technical support for the development of chicken products which was healthy,green and accepted by consumers.The purpose of this study was to examine the effectiveness of transglutaminase as acatalyst for the interaction of chicken and soy proteins by sodium dodecylsulfate-polyacrylmide gel electrophoresis,differential scanning calorimetry,fluorescencespectrosc-opy,laser light scattering instrument,as well as determination of change in turbidity.Furthermore,we investigated the contribution of enzyme-induced cross-linking to thegel-forming ability and emulsifying properties of the protein mixtures,which are related tothe textural and functional properties of the chicken products.The results are as follows.(1)Electrophoretic patterns of the proteins showed that catalysis of enzyme made thecolor of the major protein bands become light,while the macromolecular protein bandappear deeper and deeper in color in the top of the map, which indicated the occurrence ofcovalent cross-linking reaction between chicken and soy proteins.(2)The measurement of differential thermal scanning found that the temperaturemaxima for denaturation of proteins,including myofibrillar protein,globulin andβ-conglycinin,increased7-9℃after incubation with enzyme.This phenomenon suggestedthat enzyme-induced covalent cross-linking made the structure of protein more stable.(3)After scanning by fluorescence spectrophotometer,the maximum absorptionwavelength(λmax) shifted about5nm(red shift).The shift in λmaxreflected the transference ofsome of the amino acid residues that could produce fluorescence to a more polarenvironment.(4)Laser light scattering pattern showed that the average scattering intensity increased with the extension of enzyme-incubated time because of the largen of the proteinparticles:myofibrillar protein from0.33to8.0;soy protein from1.20to5.73;the mixturesfrom0.55to8.04.In addition,the absorption of the proteins at320nm increased.Becausethe size of protein aggregates induced by enzyme block the scatter light,so reducetransmittance and enhance absorption.(5)Water holding capacity of proteins mixed gel was reduced from82%to21%whensoy protein was added.With the increasing addition level of soy protein,there even beunable to form a gel.The addition of soy protein also weaken the emulsifying capacity ofmixed proteins,from6.48m2/g to3.84m2/g.However,when TG was utilized,the waterholding capacity and emulsifying capacity were improved very well,respectively to95%and13m2/g.(6)Transglutaminase and soy protein could effectively increase the hardness ofchicken products (from0.29kgf to0.71kgf) and make up the unfavorable influence broughtby soy protein,such as reducing product’s viscoelasticity and cohesion and soon.Transglutaminase-catalyzed protein covalent cross-linking also reduced cooking lossrate from33.84%to8.20%and improved the yield rate of products from83.59%to93.28%.