Enhancing the emulsifying properties of zein via alkali-heat treatment and konjac glucomannan complexation for stabilizing Pickering emulsions
Journal
International Journal of Biological Macromolecules
Journal Volume
337
Start Page
149549
ISSN
01418130
Date Issued
2026-01
Author(s)
Abstract
Zein, as an alcohol-soluble protein, in its native state is unsuitable for direct emulsion stabilization. In this study, zein was first subjected to alkali-heat treatment to enhance its hydrophilicity, obtaining alkali-heat-treated zein (AHZ). AHZ was then complexed with konjac glucomannan (KGM) to form AHZ-KGM complexes for stabilizing Pickering emulsions. Compared with AHZ alone, the AHZ-KGM complexes significantly improved emulsion stability, micromorphology, and microstructure. The emulsifying activity index (EAI) and emulsion stability index (ESI) of the emulsion increased to 50.251 m2/g and 48.893 min, respectively. Systematic analysis revealed that the complexes exhibited more fragmented and discrete micromorphologies, with KGM acting as a binder between AHZ particles. The surface and interfacial tensions of AHZ-KGM were significantly lower than those of AHZ. The complexes displayed smaller particle sizes (123.8 nm), more uniform distribution (0.239), and sufficient zeta potential (−25.3 mV). Moreover, the surface hydrophobicity and free sulfhydryl content of AHZ-KGM increased to 1473.1 (from 852.8) and 0.26 mmol/g (from 0.064 mmol/g), respectively, while the contact angle approached 90°, indicating enhanced amphiphilicity. Furthermore, spectral analysis revealed a decrease in α-helix content from 19.4 % (AHZ) to 17.3 % (AHZ-KGM), accompanied by an increase in β-sheet content from 18.6 % to 25.2 %. Hydrogen bonding played a key role in the interaction between the two monomers. These findings suggest that alkali-heat treatment combined with KGM complexation is a possible strategy for improving the emulsifying ability of zein, enabling its application in the stabilization of oil-in-water (O/W) Pickering emulsions.
Subjects
Contact angle
Emulsion stability
Interfacial tension
Surface hydrophobicity
Wettability
Publisher
Elsevier B.V.
Description
Article number 149549.
Type
journal article