Carrageenan, Epigallocatechin gallate, Astringency, Molecular mechanism, β casein, Polyphenols, Nutrition. Foods and food supply, TX341-641, Food processing and manufacture, TP368-456

The astringency of natural polyphenols affects consumers' acceptance for food, and it is urgent to find safe and effective astringency-masking substances. This study introduced ι-carrageenan (CA) as a novel astringency-masking agent and investigated its interaction mechanism using epigallocatechin gallate (EGCG) and β-casein (βCN) as model compounds. Sensory evaluation demonstrated that 0.3 % CA achieved a 56–80 % reduction in astringency intensity scores for four polyphenols, with masking efficacy exhibiting concentration-dependent enhancement. Through integrated analytical approaches including techniques such as multispectral analysis and isothermal titration calorimetry, we revealed concentration-dependent interference patterns in EGCG-βCN interactions. Three distinct mechanisms were elucidated: (1) Competitive binding with βCN to inhibit EGCG-induced protein precipitation; (2) Facilitation of βCN aggregation into higher molecular weight coacervates; (3) Formation of ternary EGCG-CA-βCN complexes. These findings highlight the potential of CA in the development of low astringency functional foods, providing the food industry with a new strategy for masking astringency.