Effect of glucose glycosylation following limited enzymatic hydrolysis on functional and conformational properties of black bean protein isolate

Abstract

The effect of glycosylation following limited enzymatic hydrolysis on conformational and functional properties of black bean protein isolate (BBPI) was investigated in this study. The black bean protein hydrolysate (HBBPI) was prepared using alcalase at pH 9.0 and then glycosylated with glucose (G) at 80 °C for different incubation times from 1 to 6 h. Grafted HBBPI with glucose (HBBPI-G conjugates) had a higher molecular weight than HBBPI by SDS-PAGE analysis. HBBPI-G conjugates had a higher content of β-turn and random coil, but a lower content of α-helix and β-sheet structure than BBPI. HBBPI-G conjugates had lower fluorescence intensity and exhibited bathochromic shift compared with BBPI. Subsequently, the functional properties were also evaluated. Results indicated that the emulsifying activity and solubility were obviously improved (P < 0.05) by HBBPI-G conjugates incubated for 4 h with 6.5% degree of hydrolysis compared to BBPI. Additionally, the glycosylation had positive effects on the reducing power and hydroxyl radical scavenging rate. Therefore, the combination of limited hydrolysis and glycation can be used as an effective method for BBPI modification to obtain enhanced functional properties.