Hydration effect of whey protein treated by glow discharge plasma.

Glow discharge plasma (GP) was used to study the hydration mechanism of whey protein with different moisture content (10%, 20%, 30%). When the moisture content was 20%, the effect was most obvious. Strong hydration effect was confirmed by Fourier transform infrared spectroscopy (FTIR) results with sharper, narrower and blue-shifted from 3283.49 cm−1 to 3286.26 cm−1, indicating the enhanced hydrogen bond. More flexible protein structure with a significant decrease in α-helix content (from 18.50% to 14.62%), β-sheet content (from 29.67% to 19.38%) and crystallinity degree (from 6.18% to 0.81%) was introduced. Whey protein underwent oxidation reactions of C C to C–O–C(H) and further to COOH, C–OH to C–O–C and sulfhydryl to disulfide bonds. The scanning electron microscopy (SEM) results showed that the treated whey protein was highly aggregated (from 55.40 μm to 226.87 μm) and formed porous and rough polymers. Additionally, the treated whey protein exhibited higher anti-oxidation activity, with DPPH, ABTS and OH free radicals increased by 14.55%, 11.08% and 15.56%. The water/oil holding capacity and light transmittance of whey protein was improved by 18.18%, 22.05% and 35.69%, respectively. [Display omitted] • Hydration effect confirmed by FTIR result at 3434.43 cm−1 and 3526.98 cm−1. • A flexible structure with decreased α-helix, β-sheet content and crystalline degree. • Whey protein underwent oxidation of C C to C–O–C to COOH, C–OH to C–O–C, SH to SS. • Whey protein were highly aggregated and etched, forming porous and rough granules. • It had better water/oil holding capacity, anti-oxidation and light transmittance. [ABSTRACT FROM AUTHOR]