Improved analysis of grape seed extract by liquid chromatography–high resolution mass spectrometry (LC-HRMS) reveals that proanthocyanidin-protein interaction mechanisms in cream depend on degree of polymerization

[Display omitted] •Improved thiolysis and LC-HRMS analysis were applied to grape seed extract proanthocyanidins (PACs).•GSE PACs with DPs up to 16 were identified by improved HRMS data processing.•DP affected interactions of PAC with cream proteins and the physical property of cream.•Low-DP PACs primarily engaged in hydrogen bonding with cream proteins.•High-DP PACs mainly utilized multiple hydrophobic interaction to form aggregates. This study aimed to comprehensively characterize chemical profiles of proanthocyanidins (PACs) from grape seed extract (GSE), examine their interactions with proteins in a cream system, and define the mechanisms mediating PAC-protein interactions. GSE PACs were fractionated and characterized by thiolysis followed by liquid chromatography–high resolution mass spectrometry (LC-HRMS) analysis. New PACs with a degree of polymerization (DP) up to 16 were identified by improved HRMS data processing methods. In the model cream system, high-DP PACs exhibited greater precipitation capacity and protein binding than low-DP PACs. Low-DP PACs primarily engaged in hydrogen bonding, while high-DP PACs predominantly utilized multiple hydrophobic interaction sites to form cream protein aggregates. Furthermore, particle size and viscosity measurement of cream revealed a progressively DP-dependent increase in aggregated fat globules and cream viscosity. These findings enhanced our understanding of PACs’ structural intricacies and highlighted their functional role as PAC-rich natural ingredients in creating structured cream systems.