In situ enzymatic synthesis and purification of theaflavin‐3,3′‐digallate monomer and incorporation into nanoliposome

Summary The aim of this study was to develop a novel ethanol‐water based enzymatic synthesis coupled with column chromatography purification technique to synthesise theaflavin‐3,3′‐digallate (TFDG) using underutilised summer and autumn fresh tea leaves. Enzymatic synthesised TFDG was incorporated into nanoliposome using ethanol injection combined with dynamic high‐pressure microfluidisation technique at pH 5.5. TFDG with a purity of 90.5% at the gram level was achieved by applying ethanol with different concentrations as eluent, and the yield of TFDG was 36.00%. TFDG nanoliposome showed the great in vitro digestion stability, with the particle size, polydispersity, zeta potential being 59.43 ± 5.67 nm, 0.31 ± 0.025 and ‐8.28 ± 0.24 mV, respectively. Nanoliposome encapsulation can significantly improve the stability of TFDG as indicated by the greater resistance upon in vitro digestion studies under both the mild alkaline pH and simulated intestinal fluid. The current research laid a foundation for the further application of TFDG as functional ingredients in food industry.