Emulsifying Properties of Hops β-Acids Extract: Linking Microstructure to Function in Toothpaste Systems

Surface-active agents (surfactants) are essential excipients of toothpaste formulations, where they reduce surface and interfacial tension to enable wetting, dispersion, and emulsification of hydrophobic ingredients such as flavor oils. Of increasing interest is the development of alternative surfactants to enhance toothpaste cleaning performance and provide greater formulation flexibility to modulate interfacial behavior and micelle structure/colloidal organization. Hops beta (β)-acids extract contains amphiphilic molecules that have exhibited surface activity, although the relationship between its structure and behavior is not fully characterized.

In this study, hops β-acids extract (Activ Bio-Cleanser™) was evaluated as a surface-active component in toothpaste-relevant model systems using computational analysis, equilibrium and dynamic surface tension measurements, cryogenic electron microscopy (cryo-EM), and headspace flavor analysis.

The principal hops β-acid homologues showed theoretical critical micelle concentrations in the low millimolar range, and hops β-acids extract reduced both equilibrium and dynamic surface tension, including in mixed systems with sodium lauryl sulfate. Microstructure analysis by cryo-EM further revealed that hops β-acids extract altered colloidal organization of the toothpaste simple solutions, promoting spherical micelles while increasing the abundance of multilamellar vesicles and lamellar-like structures. These changes were accompanied by reduced headspace release of representative hydrophobic flavor compounds after dilution.

The results confirm that hops β-acids extract demonstrates surface-active behavior in toothpaste systems and contributes to emulsification of hydrophobic components by promoting colloidal polymorphism. The observed reorganization of self-assembled structures provides a physicochemical basis for its role in emulsification and retention of hydrophobic components within formulations. These findings validate that hops β-acid surfactant properties persist when incorporated into toothpaste formulations and can modulate surface and interfacial behavior.

Through its contribution as a surfactant, hops β-acids extract provides a formulation approach to support improved cleaning-related performance and sensory attributes.