Effects of high pressure microfluidization on the structure and rheological properties of Akebia trifoliata var. australis seed protein isolate

In this study, Fourier transform infrared spectroscopy (FT-IR) and steady shear rheology were carried out to investigate the effects of high pressure microfluidization (HPM, 0.1, 50, 90, 130, 170 MPa) on the conformational and rheological properties of Akebia trifoliata var. australis seed protein isolate (API). The results showed that after HPM treatment, the particle size of API became smaller, subunits of API were unchanged, and solubility increased significantly, as demonstrated by SDS-PAGE. The contents of the total and exposed sulfydryl decreased with increasing pressure. The FT-IR results suggest that the secondary structure of API changed, and the maximum change occurred when the pressure was 130 MPa; the contents of unstable structures such as β-sheets and random coils decreased, while the stable β-turn protein structure content increased, resulting in improved conformational stability of the sample. Rheology measurement indicated that the API solution was a pseudoplastic liquid both before and after HPM treatment, the apparent viscosity of all API solution samples showed a decreasing trend when the shear rate ranged from 0 s-1 to 10 s-1. With the increase of treatment pressure, the apparent viscosity of the API solution showed obvious shear-thinning phenomenon. ©, 2015, South China University of Technology. All right reserved.