高压微射流处理对白木通籽分离蛋白结构及流变性质的影响

Effects of High Pressure Microfluidization on the Structure and Rheological Properties of Akebia trifoliata var. australis Seed Protein Isolate

本文采用了傅里叶红外光谱（FT-IR）和稳态剪切流变学等分析方法研究了高压微射流处理（0.1、50、90、130、170 MPa）对白木通籽分离蛋白结构及流变性质的影响。结果表明：经过高压微射流处理,白木通籽分离蛋白的粒径变小;SDS-PAGE电泳结果表明,蛋白亚基未受影响;溶解性得到显著提高;总巯基以及暴露巯基的含量随着处理压力的增大呈下降趋势;FTIR结果表明,分离蛋白的二级结构组成发生了变化,在130 MPa时变化最大,并且蛋白的不稳定结构如β-sheet、Random coil含量减少,稳定的蛋白结构β-turn含量增加,样品构象稳定性提高。白木通籽分离蛋白溶液经微射流处理前后均是假塑性流体,在剪切速率为0-10 s^-1范围内,表观粘度呈递减的趋势;同时随着样品处理压力的增大,表观粘度发生明显的剪切稀化现象。

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.