Advances in terahertz solution-phase sensing for food analysis: Principles, metamaterial-enhanced microfluidics, and functional material integration.

Terahertz (THz) spectroscopy offers unique capabilities for probing molecular vibrations in food analysis, yet faces inherent challenges from strong water absorption in aqueous systems, particularly matrix interference in liquid foods and limited detection sensitivity for trace contaminants. To overcome this limitation, recent advances employ microfluidic confinement, metamaterial enhancement, and hybrid sensing architectures, thus enabling high sensitivity for liquid food analysis. This review systematically examines fundamental THz sensing modes, metamaterial-assisted platforms with microfluidic integration, and functional materials to mitigate water absorption. Distinct from prior works, we focus on food-specific applications, highlighting emerging cases in authentic samples while addressing the current reliance on model solutions. Future pathways emphasize multimodal sensing fusion with microfluidic automation and AI-driven signal processing to resolve matrix complexity, enabling regulatory adoption and practical implementation in liquid food matrices.