Study On The Preparation, Characteristic And Application Of Pea Protein Isolate

In this paper ,with the utilization of pea as the main raw material, the alkaline-solution and acid- precipitation process to extract the pea protein isolate(PPI) from the pea was optimized,the ultrasound–assisted extraction process based on which pea protein isolate(PPI) was prepared was also investigated ,and then the various functional properties of PPI prepared were determined. The modification of PPI was studied in this paper in order to improve the application characteristic of PPI, Finally,PPI was added to the ham that was studied.Firstly,the main components of the pea has been analyzed.The components were starch52.8%,protein23.2%,fiber10.8%,fat1.3% and ash2.6%.According to the single factor (solid-liquid ratio,pH,extraction temperature, extraction time) and orthogonal test,the optimum extraction conditions were determined: solid-liquid ratio 1:25, pH9.0, extraction temperature 45℃,extraction time 50min。Upon the optimum conditions ,the pea protein isolate extraction is 81.82%, protein content is 91.23%, pea protein isolate(PPI) extraction rate could be improved by 1.39% through the ultrasound-assisted alkaline extraction and acid precipitation method. The amino acid composition of PPI was analyzed and the proportion of the essential amino acids was closer to the FAO recommended values, among which, lysine was in a particular high level.Secondly, the various functional properties of PPI were studied, taking nitrogen soluble index(NSI) as an indictor,the effect on the solubility of PPI by the elements related: pH, temperature, ion strength, and protein concentration was investigated and a preferable PPI solubility was pH9.0,ion strength 0.1mol/L,temperature 50℃,the effect on foaming and emulsifying properties of PPI by the elements pH,ionic strength, temperature and protein concentration was studied. According to the comparisons of the functional properties between freeze-drying PPI and spray-drying PPI,in addition to viscosity,freeze-drying PPI show superior properties to the spray-drying.PPI.Through comparing, however, the functional properties of PPI was not better than other plants protein, so the transglutaminase(TG) modification treatment to PPI was adopted and the results showed that the modified PPI had improved greatly in the functional properties than the unmodified, especially in the emulsifying and gelatinizing properties. In order to clarify the mechanism of TG in the PPI modification process. So that further isolation of .PPI with Sephacryl S-200 was applied and the changes of the subunits were observed by the SDS-PAGE electrophoresis on the various isolated components before and after TG modification.The main components of the PPI were 11S legumin50%,7S vicilin20% and albumin26%.The subunits of the three proteins were decrease before and after TG modification and 7S vicilin was play key role in the reaction.The subunits components of the three proteins had been analyzed by SDS-PAGE electrophoresis.Finally pre-and post-modified PPI were added to the ham for preliminary exploration of its application.