Structural and antioxidative properties of royal jelly protein by partial enzymatic hydrolysis

The objective of this study was to investigate the structural and antioxidative properties of royal jelly protein (RJP) at different degrees of hydrolysis (DH) by partial enzymatic hydrolysis. RJP was hydrolyzed by alcalase for 0 min, 15 min, 1 h, 5 h and 8 h to obtain hydrolysates at DH of 5.34%, 11.65%, 15.19%, 21.38% and 23.91%, respectively. With the increased DH, the RJP hydrolysates showed elevated antioxidative activities. The molecular weight of RJP hydrolysates was significantly decreased but their primary backbone kept unchanged. Analysis of circular dichroism spectra revealed that the enzymolysis reduced the content of alpha-helix but increased the contents of fl-sheet, fl-turn and random coil. Meanwhile, the surface hydrophobicity and fluorescence intensity of RJP hydrolysates were decreased and a red shift occurred. As the enzymolysis continued, the surface morphology of RJP was gradually changed from a sheet-like structure into microparticles. Changes in antioxidative activities and structures generally followed a DH-dependent manner, however these changes became insignificant for samples at DH beyond 20%. Taking into consideration of both effectiveness and productivity, the optimum enzymatic duration was determined at 5 h.(c) 2023 Beijing Academy of Food Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The purpose of this study was to investigate the effects of enzymatic hydrolysis on the structural and antioxidative properties of royal jelly protein (RJP). Different degrees of hydrolysis (DH) were obtained by hydrolyzing RJP for different durations. The antioxidative activity of RJP hydrolysates increased with the DH, while the molecular weight decreased. Enzymolysis led to changes in secondary structures, surface hydrophobicity, fluorescence intensity, and morphology of RJP. The changes followed a DH-dependent manner, but became insignificant beyond 20% DH. The optimum enzymatic duration was determined to be 5 hours.