Research advancements on the biomimetic generation and stability strategies of theaflavins: from mechanisms, synthesis influencing factors to encapsulation with nanomaterials

Theaflavins (TFs), natural orange-red tea pigments formed during tea fermentation and characterized by a benzophenone structure, are known for their multiple potential health benefits. However, their low content in black tea and instability pose challenges for the industrial production of high-purity TF products, limiting their broader application. A comprehensive understanding of current methods for synthesizing TFs is crucial for their industrialization. This review highlights the formation mechanism and the biomimetic synthesis of TFs, particularly the enzymatic approach and its various influencing factors. Additionally, recent advances in enhancing the stability of TFs are briefly introduced. Although significant breakthroughs have been realized in the in vitro enzymatic synthesis of TFs, enzymatic methodologies still face substantial challenges in scaling up for commercial production, while the directed synthesis of specific TF monomers remains technically constrained. As a result, exploring targeted synthesis processes for TFs is still a focal point for future research. Furthermore, the search for novel and efficient delivery systems to enhance the bioavailability of TFs is imperative for expanding the utilization and application scope of TFs.