Isolation of B-constituent through selective complex coacervation of hordein with ι-carrageenan

The complex behavior of the crude hordein with ι-carrageenan (Car) as a function of pH (11.0–3.0) and Hordein/Car mass ratios (20:1–1:1, w /w) was studied through zeta potential analysis, turbidimetric titration and SDS-PAGE. By preferential binding with Car, B-hordein was isolated from the crude hordein at pH max (6.2) and Hordein/Car mass ratio of 15:1, which was further confirmed by LC-MS/MS analysis. The results of zeta potential and size of separated B-hordein and C-hordein suggested that the difference in charge density was the main driving force of selective complexation between hordein and Car. Simultaneously, Fourier transform infrared spectroscopy also confirmed the existence of strong electrostatic interaction between B-hordein and Car. Additionally, the more ordered secondary structure of B-hordein at pH max might be beneficial to its preferential binding with Car. This study further promotes the application of B-hordein in food industry. • The selective complexation was used to isolate the main constituents of hordein. • The hordein/ι-carrageenan mass ratio can be optimized to isolate B-hordein. • Differences in charge density and protein conformation led to preferential binding.