Effect Of Soybean Protein Isolate/Konjac Glucomannan Complex Functional Properties And Interactions On Ultra-high Hydrostatic Pressure

The gel and sol state of SPI/KGM complexes were prepared by high hydrostatic pressure treatment method using soybean protein isolated (SPI) and konjac glucomannan (KGM) as core materials. Study was developed to explore some change of its function such as gel strength, shear viscosity and emulsification, emulsifying stability, water features. In addition their interaction mechanism was studied. The main content of research were as follow:(1) The preparation process conditions of SPI/KGM complex such as the concentration of complex and ion, ratio of KGM and SPI, the amount of Ca(OH)2addition were studied by testing the strength of gel and the loss of water. The response surface method was developed to obtain the optimized processing conditions subsequently, and the strength of gel was set as response value. The optimization results were:the concentration of complex and KC1were4.66%and0.13mol/L respectively, the ratio of KGM and SPI was1:3.23, the Ca(OH)2level was0.15g.(2) the preparation conditions of SPI-KGM composite sol were investigated, to explore the effect of ion concentration, pH, temperature on the composite sol emulsion, emulsion stability and viscosity. Then the emulsion was as response value to determine the optimized processing conditions of composite sol through the response surface method. The results of optimization:the temperature, pH and the addition of KC1were53.98℃,8.12and0.02mol/L individually.(3) The optimized gel was treated with pressure to study effect of different level of pressure and the duration of the pressure on the gel as well as its function properties. The untreated gel were set as control. The results showed that, the pressure level and duration time existed the similar influence to the gel function. By studying the strength and loss water of gel as well as the composite sol emulsification, emulsion stability, viscosity to make sure the gel was the best whem pressure was400MPa last for15min. Gel strength composite gel reached3.21N, composite sol emulsification of2.309, emulsion stability was93.62%, while the viscosity reaches12.37Pa.s at5s-1, composite gel to minimize water loss rate. Composite gel water loss rate reaches a minimum at200MPa, the water loss rate of7.15percent.(4) In unpressurized control samples, composite sol gel and scanning electron microscopy and Fourier transform infrared spectroscopy scanning. Scanning electron microscopy results obtained after pressing space structure of the sample becomes more closely, soy protein isolate and strengthen the interaction between KGM samples400MPa effect after treatment to achieve the best; Meanwhile, Fourier transform infrared scan draw high-pressure treatment to make protein degradation, expand and improve the interaction between molecules, in addition, the absorption peaks of OH and NH composite system to a low-band displacement, high pressure treatment enhanced the role of the composite system of hydrogen bonds. This result illustrates the functional properties of the composite high-pressure treatment system improved reasons.