Formation, Structural Characteristics and Emulsification Properties of Mung Bean Globulin Amyloid Fibrils

Abstract

In this study, the structural evolution of mung bean globular amyloid fibrils (MBGFs) during the formation process was investigated with different acid-heat treatment times, and the emulsification properties of MBGFs were also explored at each stage of the formation process. The results showed that the subunits of mung bean globulin (MBG) were gradually degraded and hydrolyzed into fibrous structure units mainly composed of small peptides during 0–12 h of heating. And a large number of β-sheet structures were produced, and its relative content increased from an initial level of (18.28 ± 0.75)% to (53.61 ± 1.15)% over the 12 heating period. Enhanced fluorescence intensity was recorded after combination with thioflavin-T. Morphologically, MBGFs gradually became elongated and pliable, and oriented fibril aggregation occurred in the heating process. Between 16 and 24 h, the structure of mature MBGFs gradually was dissociated and the structural characteristics of the fibers were destroyed. The emulsification activity, emulsion stability, protein adsorption rate and interfacial protein content of MBGF were significantly improved compared with those of MBG. MBGFs formed by acid-heat treatment for 4 h had the best emulsification properties. Oil droplets in the MBGF emulsion were small in size, uniformly and orderly distributed, and the emulsion had the highest apparent viscosity and showed an elastic gel structure. In conclusion, different acid-heat treatment times had significant effects on the structure and emulsification properties of MBGFs, and MBGFs had better emulsification properties than MBG. This study will provide theoretical support for clarifying the formation of MBGFs and ideas for the development of highly efficient food-grade emulsifiers.

Keywords

• mung bean globulin; protein amyloid fibril; structural characteristics; emulsification properties