Investigation of the astringency-masking effect of ι-carrageenan on natural polyphenols and its differential mechanism at various concentrations

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.