Innovative multistep modifications of β-Lactoglobulin for enhanced emulsifying and antioxidant activities

Abstract

This aim of this study was to investigate the effects of limited enzymatic hydrolysis (H), glycation (G), and amyloid fibril (F) modification on the emulsifying and antioxidant activities of β-Lactoglobulin (β-Lg). Changes in the physicochemical properties of limited enzymatic hydrolysis-modified β-Lg (Hβ-Lg), glycation by maltodextrin (Mal) -modified Hβ-Lg (GHβ-Lg), and amyloid fibril-modified GHβ-Lg (FGHβ-Lg) were observed through free amino acid content, sodium dodecyl sulfate‒polyacrylamide gel electrophoresis profiles and ThT fluorescence intensity. The structural changes and microscopic morphology of the modified proteins were determined by circular dichroism, Fourier transform infrared spectroscopy and transmission electron microscopy. Circular dichroism analysis showed that the β-structure content of FHβ-Lg increased, while the secondary structure of FGHβ-Lg was preserved. Finally, the functional activities of the modified proteins were evaluated. Comparing β-Lg with FGHβ-Lg or GHβ-Lg, the emulsifying activity of FGHβ-Lg increased from 9.38 m2/g to 24.37 m2/g, while the emulsifying stability of GHβ-Lg increased from 48.93 min to 131.22 min. Finally, the antioxidant activities of the modified proteins were determined by reducing power (β-Lg: 0.17, FGHβ-Lg: 0.27), ABTS·+ scavenging activity (β-Lg: 75.91%, FGHβ-Lg: 86.33%), Fe2+ chelating activity (β-Lg: 54.30%, FGHβ-Lg: 75.49%), and DPPH scavenging ability (β-Lg: 67.43%, FGHβ-Lg: 77.13%). Overall, our findings suggest that FGHβ-Lg has great potential in the development of protein emulsifiers with high antioxidant activities.