Journal of Biology and Nature

Butterfly pea (Clitoria ternatea L.) flower has moved from a regional culinary and traditional-medicine ingredient to an internationally traded source of blue-to-purple colouration, driven by regulatory approval in several jurisdictions and by consumer demand for clean-label alternatives to synthetic dyes. Its principal pigments, a family of polyacylated delphinidin glycosides known as ternatins, combine an intense, pH-responsive hue with structural stability exceeding that of most non-acylated anthocyanins, while the same extract is repeatedly described as a source of antioxidant, antidiabetic and other bioactive effects. Existing reviews have tended to address the species' phytochemistry, colourant behaviour or pharmacology as separate literatures, and several recent syntheses extend into cosmetic, packaging and broader medicinal territory without sustaining a food-product-specific focus. This critical narrative review addresses that fragmentation by jointly evaluating the technological performance of C. ternatea extracts as food colourants and their behaviour as functional ingredients once incorporated into real food matrices, rather than as isolated solutions. It synthesises evidence on ternatin structure and biosynthesis, extraction and stabilisation strategies, colour behaviour under processing- and storage-relevant conditions, applications in beverages, bakery, dairy and other products, and the strength of evidence for claimed antioxidant, antidiabetic, anti-inflammatory and other physiological effects, explicitly distinguishing in vitro, animal and the still-limited human evidence. It also examines an unresolved regulatory divergence in which the extract has been approved and progressively expanded as a colour additive in the United States while the dried flower has met safety objections as a traditional food in the European Union. The available evidence supports the extract's technological viability as a colourant, particularly in acidic to neutral, encapsulated or low-light systems, and provides consistent preclinical support for antioxidant and carbohydrate-digestive-enzyme-inhibitory activity, but clinical substantiation remains confined to a small number of acute human trials, extraction and reporting practices are heterogeneous, and long-term safety and efficacy data in real food matrices are limited. The review identifies standardisation of extract characterisation, matrix-specific stability and bioaccessibility testing, and adequately powered human trials as the most consequential priorities for translating this ingredient from a demonstrated laboratory candidate into a substantiated functional food component.