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

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 ll-Lactoglobulin (ll-Lg). Changes in the physicochemical properties of limited enzymatic hydrolysis-modified ll-Lg (Hll-Lg), glycation by maltodextrin (Mal)-modified Hll-Lg (GHll-Lg), and amyloid fibril-modified GHll-Lg (FGHll-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 ll-structure content of FHll-Lg increased, while the secondary structure of FGHll-Lg was preserved. Finally, the functional activities of the modified proteins were evaluated. Comparing ll-Lg with FGHll-Lg or GHll-Lg, the emulsifying activity of FGHll-Lg increased from 9.38 m2/g to 24.37 m2/g, while the emulsifying stability of GHll-Lg increased from 48.93 min to 131.22 min. Finally, the antioxidant activities of the modified proteins were determined by reducing power (ll-Lg: 0.17, FGHll-Lg: 0.27), ABTS' thorn scavenging activity (ll-Lg: 75.91%, FGHll-Lg: 86.33%), Fe2+ chelating activity (ll-Lg: 54.30%, FGHll-Lg: 75.49%), and DPPH center dot scavenging ability (ll-Lg: 67.43%, FGHll-Lg: 77.13%). Overall, our findings suggest that FGHll-Lg has great potential in the development of protein emulsifiers with high antioxidant activities.