Effects Of Konjac Flour,Transglutaminase And Soybean Protein Isolate On Gel Properties Of Common Carp Myofibrillar Protein

In the paper, the effects of konjac flour (adding concentration at0,0.05,0.10,0.15and0.20%; different heat temperature70,80and90℃; different NaCl concentration0,0.05,0.10,0.15and0.20M), transglutaminase (0,0.10,0.20,0.30,0.40and0.50%) and soybean protein isolate (different types:nature SPI, SPI preheated at90℃for30min and180min; SPI adding concentration:SPI/MPI=1:1,1:2,1:3and1:4) on the physicochemical and gels properties of common carp myofibrillar protein isolate were investigated by determination of turbidity, emulsifying propertities and surface hydrophobicity of myofibrillar protein, TPA (hardness, springiness, adhesiveness and resillence), whiteness, water-holding capacity, rheological properties SDS-PAGE and microstructure of myofibrillar protein gel. It illuminated mechanism of these addition ingredients improve myofibrillar protein gel properties. Deep processing and improvement products quality of freshwater fish were carried out on the basis of obtained results. The results were as follows:1. The effect of addition ingredients on the common carp MPI physicochemical properties:(1) The effect of konjac flour on the common carp MPI physicochemical propertiesUnder the same temperature, turbidity increased significant with increased konjac flour content (P<0.05), and reached maximum at80℃; under the same konjac flour content, turbidity increased with the temperature increased from30to80℃. EAI and ESI increased then decreased as the increased of konjac flour content, and EAI and ESI reached maximum26.92m2/g and83.79%by adding0.1%konjac flour. The surface hydrophobicity rised as konjac flour content increasing.(2) The effect of transgluminase on the common carp MPI physicochemical propertiesUnder the same temperature, turbidity declined with TG adding level increased. With the TG adding content increased, EAI decreased gradually and ESI increased then decreased. Moreover, ESI reached maximum72.93%while TG adding content was0.3%. After adding TG, the surface hydrophobicity increased significantly (P<0.05).2. The effect of addition ingredients on the common carp MPI gel properties: (1) The effect of konjac flour on the common carp MPI gel propertiesUnder the same adding level of konjac flour, myofibrillar protein gel hardness and springiness at80℃were higher than gel hardness and springiness at70and90℃significant (P<0.05), hardness and springiness increased by adding NaCl; Under the same temperature, and hardness reached maximum129g by adding0.1%konjac flour. Under the same adding level of konjac flour, water-holding capacity at90℃was higher than water-holding capacity at70℃significantly (P<0.05), water-holding capacity improved significantly with NaCl concentration increased. Under the same temperature, whiteness decreased slowly as the concentration of konjac flour increased, whiteness at90℃decreased significantly than70and80℃(P<0.05), Gel whiteness improved significantly by adding NaCl, water-holding capacity increased with konjac flour concentration increased. With the konjac flour content increasing, storage modulus G’and loss modulus G" increased gradually, also increased G’max, gel network became more compact and regular. It showed that KF could raise thermal denaturation temperature, and improve gel network structure.(2) The effect of transgluminase on the common carp MPI gel propertiesHardness, springiness, adhesiveness and resillence increased gradually with TG adding content, it suggested that TG could improve MPI gel profile significantly. Water-holding capacity increased with TG adding level, but whiteness contrary. When the adding level was0.4%, water-holding capacity approached to pure MPI gel. With TG adding content increasing, G’and G" increased, gel network became more compact, space smaller and smaller.(3) The effect of SPI on the common carp MPI physicochemical propertiesThe hardness, springiness, whiteness and rheological property of gel prepared with MPI and native SPI mixtures were significantly lower than those treated with either pure MPI or MPI and preheated SPI mixtures (P<0.05). Further more, the gelling properties prepared with MPI and SPI preheated at90℃for180min were higher than that preheated for30min. The hardness, springiness and whiteness increased gradually with the ratio (SPI/MPI) increased from1:1to1:4. The water-holding capacity reached maximum when the ratio was1:3while heating at90℃for180min. Storage modulus G’of all the preheated treatment at90℃samples were higher than samples that mixture of native SPI and MPI significantly (P<0.05). These suggested that preheated SPI was a potential addictive that could improve the gel properties of MPI in food industry.