Encapsulation of EGCG by whey protein isolate and β-cyclodextrin nanocomplexes: A strategy to mask the bitter and astringent taste and increase the stability in beverages

(−)-Epigallocatechin-3-gallate (EGCG) is the main active component of tea polyphenols, which endows tea with bitter and astringent taste and is susceptible to degradation in presence of light, heat and oxygen. In this study, whey protein isolate (WPI) and β-cyclodextrin (β-CD) were used to prepare the WPI-β-CD nanocomplexes for masking the bitter taste and protecting EGCG. The encapsulation efficiency of EGCG by WPI-β-CD nanocomplexes reached to 79.61%. Sensory evaluation indicated that the bitter and astringent taste of EGCG was masked. FTIR results suggested that the WPI/β-CD-EGCG nanocomplexes were formed through electrostatic, hydrogen bonding and hydrophobic interactions among WPI, β-CD and EGCG. The molecular mechanism of taste masking was preliminarily investigated by molecular docking, suggesting that the bitter and astringent taste moiety of EGCG was inserted into the hydrophobic cavity of β-CD, thereby masking the bitter and astringent taste of EGCG. The results of in vitro gastrointestinal experiments and scanning electron microscopy indicated that the WPI-β-CD nanocomplexes effectively encapsulated EGCG and achieved sustained release in simulated gastrointestinal conditions, thus showing potential application prospects in tea beverages and related areas.