Non-covalent interactions between pectin and volatiles modulate flavor formation in goji berry (Lycium barbarum L.) during pulsed vacuum drying

Pectin plays a crucial role in modulating the flavor attributes of goji berry. This study investigated dynamic variations of volatile organic compounds (VOCs), non-volatile organic compounds (NVOCs), and pectin fractions, as well as their interactions in goji berry during pulsed vacuum drying (PVD), focusing on the chelator-soluble pectin (CSP) fraction. The results showed that 121 differential VOCs (DVOCs) were identified throughout the PVD process. The transition from stage III to V, during which rapid moisture migration occurred, was determined as the critical period for flavor formation. NVOCs involving soluble sugars, organic acids and amino acids affected VOC profiles. CSP exhibited substantial nanostructural rearrangement and interconnected network reconstruction, showing strong negative correlations with key aroma-active compounds such as acetic acid and octanal. It was further revealed that CSP interacted with acetic acid predominantly through hydrogen bonding, while octanal binding likely involved both hydrophobic interactions and hydrogen bonding. These non-covalent interactions inhibited pectin aggregation, reduced particle size, and promoted the formation of stable porous fibrous microstructure that may facilitate flavor retention. Therefore, these findings indicate that pectin regulates flavor formation during PVD not only through structural transformation but also via non-covalent interactions with VOCs. This study provides theoretical basis for clarifying flavor-formation mechanisms of goji berry during PVD processing.