大豆分离蛋白制备方法
Preparation of soy protein isolate
SPI was prepared from flours defatted at room temperature to prevent heat denaturation of the
proteins, according to previous literature (Renkema, Lakemond, de Jongh, Gruppen, & van Vliet,
2000) with slight modifications as outlined in Fig. 1.
The flour was suspended in 100 mM Tris–HCl buffer at pH 8.0 in a 1:10 ratio (w/v), and stirred
at room temperature for 1 h. Fiber was separated by centrifugation (12,000g, 30 min, 10 󰀀C)
using a Beckman Coulter Model J2-21 (Follerton, CA) and recovered using porcelain filter with a
filter paper (Fisher Brand Qualitative P8 Filter Paper, Fisher Scientific, Pittsburgh, PA). The
supernatant was adjusted to pH 4.8 with 2 M HCl to induce precipitation of soy proteins. After 2 h
at 4 󰀀C the dispersion was centrifuged as described above. The soluble phase from this
centrifugation step (whey) was collected for further analysis. The precipitate was washed with 10
mM sodium acetate buffer at pH 4.8 (1:8 ratio (w/v)) and centrifuged as described above and the
supernatant from this washing step was discarded.The final precipitate (SPI) was suspended in
MilliQ water, adjusted to pH 7.5 and dialyzed overnight. SPI, fiber and whey were freeze dried.