Masking Bitterness Without Masking Benefit: A Critical Evaluation of Formulation Strategies for Polyphenol-rich Functional Foods and their Consequences for Consumer Acceptability

Abstract

Polyphenol-rich functional foods occupy an uncomfortable position between nutritional promise and sensory rejection. The same structural features that confer antioxidant and cardiometabolic activity also generate bitterness and astringency, and the concentrations required to approach physiologically meaningful intakes frequently exceed the concentrations that consumers will tolerate. Formulation science has responded with an expanding repertoire of masking strategies, ranging from cross-modal taste suppression with sweeteners and salts, through macromolecular sequestration by proteins and polysaccharides, to molecular inclusion in cyclodextrins and colloidal encapsulation in liposomes, emulsions and protein-polysaccharide nanocomplexes. This critical review examines whether these strategies achieve sensory improvement without a corresponding loss of the functional properties that justify fortification in the first place. Evidence was drawn from mechanistic sensory science, formulation and encapsulation research, in vitro digestion studies and consumer science, and was appraised for methodological adequacy and for the strength of the inferential link between sensory outcomes and retained benefit. The central finding is that masking efficacy and benefit retention are governed by the same physicochemical variable, namely the concentration of free polyphenol available at an interface, so that the two objectives are structurally coupled rather than independent. Studies reporting successful masking rarely measure delivery, studies reporting delivery rarely measure taste, and almost no work follows a single formulation from a validated consumer panel through to human bioavailability. Reliance on electronic-tongue signals as a substitute for human judgement, on trained panels as a substitute for consumers, and on total phenolic assays as a substitute for absorbed metabolites further weakens the evidence base. Formulation decisions should therefore be evaluated against paired sensory and delivery endpoints, benchmarked to intakes with demonstrated physiological effect, and tested under conditions that reflect informed rather than blind consumption.