Effect Of Soybean Protein Isolate On Gel Forming Properties Of Myofibrillar Protein Isolate

Soybean protein isolate (SPI) as a functional ingredient, has been widely used in processed meat products. However, the final temperature of processed meats could not sufficient to denature the structure of SPI. And also, it will inhibit the interaction between the SPI and muscle protein. In this paper, the effects of preheated, pH treated and enzyme modified SPI on the gel properties of myofibrillar protein isolate (MPI), and on the quality of the actual low-temperature meat products were studied. The results will have important theoretical and applied value for improving the rational application of SPI in meat products, and improving the quality of low-temperature meat products.In the model system, the effects of preheated, pH with heat treated and enzyme modified SPI on the gel properties of MPI were studied. SPI that were preheated at 80, 90 and 100℃for 15, 30, 60, 100 and 180min, were benefit for the gel properties of mixture of SPI and MPI. The gel mixed with MPI and SPI which was preheated at 100℃for 180min exhibited the highest storage modulus G', the gel hardness increased 55.5% and water holding capacity increased 19.2%, compared with the gel of MPI and native SPI (SPI/MPI=1/3, 4% (w/w)).SPI treated by pH3.0, 5.0, 7.0, 10.0 improved the gel properties of MPI. The gel mixed with MPI and SPI which was pretreated at pH3 exhibited the highest storage modulus G', the gel hardness increased 55.4% and water holding capacity increased 6.4%, compared with the gel of MPI and native SPI (SPI/MPI=1/3,4%(w/w)).SPI which were hydrolyzed weakened the gel properties of MPI with the increasing hydrolysis degrees. However, after reaching a certain degree (DH = 5), the increase of DH did not reduce the gel properties of MPI significantly.Then, the results of model system were applied to actual system. SPI which were preheated at 80℃for 30min, 100℃for 180min, DH=0 and 3 were added to the west sausage and brine ham, with the raw meat weight of 2% and 2.5% respectively. The results showed that preheated SPI had improve the texture of meat, while the SPI enzymolysis weakened it. However, all SPI samples had no significant on the meat color and water holding capacity.In a word, preheated SPI can improve the quality of meat products significantly than native SPI. It has guiding meaning for producing high denatured and solubility SPI in production.