Study On Gelation And Properties Of Soy Protein Isolate

Due to the characteristics of sourcing extensive and degradable,we are already seeing an increased emphasis on soy protein isolate(SPI).A large number of groups,which are on molecular chain,providing more actionable space.In this paper,cross-linking SPI gels were prepared with glutaric dialdehyde and the properties were studied.The cross-linking reaction conditions and cross-linking agent dosage of SPI gels were found using the control variate method;changing the SPI molecular conformation with glycerin,sodium dodecylsuphate(SDS)and inorganic salt,and discussing the effect of modifier on SPI gels properties;the swelling ratio was measured in different drying condition and swelling environment,and swelling laws were analysed.The effect of molecular structure changing on solution state,congelation time,swelling ratio,water states in gels,dynamic rheological behavior and microstructure were studied through rotational viscometer,spectrophotometer,differential scanning calorimeter,plate rheometer and scanning electron microscope,and the swelling type was discussed with linear regression.The results showed that:The pretreatment solution viscosity was increase with the SPI concentration raised;The raise of heating temperature and pH were helpful to improve the solution dispersion and gel texture;the increase of the amount of glutaric diadehyde was beneficial to shorten the gel time.Confirming the best experimental conditions was:SPI concentration was 10%,heating temperature was 65 ℃,pH value was 12,glutaric dialdehyde dosage was 0.5%.Appropriate amount of glycerol and SDS was added to solution,it caused solution dispersion enhanced,shorten the coagulation time and swelling rate improving,the swelling type was non-Fickian.When the glycerol content was 1.5%,the coagulation time decreased to 9min,the swelling rate reached 39.47.When the content of SDS was 0.3%,the coagulation time decreased to 8min,and the swelling rate increased to 66.03.Glycerol and SDS both caused the gel storage modulus decreasing.Compared with K+ and Na+,the effect of Mg2+ on shorten coagulation time and improving swelling rate was more obvious.When the Mg2+ ion strength was 5,the swelling ratio reached maximum,was 44.65,the coagulation time was 10min.The heating dry method and increasing of NaCl concentration decreased the swelling ratio;the increasing of temperature and pH was beneficial to water sucking,and the gel in the condition of pH4.01 to pH9.18 had pH responsiveness,it was Fickian pervasion in alkaline environment,non-Fickian in acid environment.