A novel surfactant-mediated strategy for modulating chlorophyll aggregation behavior to improve chlorophyll thermal stability in aqueous systems.

Chlorophylls face significant challenges in practical applications due to their poor aqueous solubility and thermal instability. This study investigated the relationship between chlorophyll aggregation behavior and thermal stability in aqueous systems and explored a surfactant-mediated strategy for modulating chlorophyll aggregation. Spectroscopic analysis, together with transmission electron microscopy, demonstrated that Tween 20 and Tween 80 at concentrations below their critical micelle concentrations (CMCs) promoted the formation of randomly organized chlorophyll aggregates with particle sizes ranging from 100 to 150 nm. These systems retained more than 80% of the initial chlorophyll content after thermal treatment, which was primarily attributed to the formation of strong noncovalent interactions between chlorophylls. At concentrations above the CMCs, random chlorophyll aggregates maintained over 90% chlorophyll retention after thermal treatment in Tween micelles. Molecular dynamics simulation further demonstrated that micelle formation effectively encapsulated chlorophylls within hydrophobic cores, thereby reducing their exposure to water molecules and enhancing thermal stability. Mass spectrometry identified 11 chlorophyll a-related compounds and derivatives, while Tween 80 significantly mitigated the conversion of chlorophylls into undesirable brown compounds, such as pheophytins. Overall, this study provides molecular-level insights into the relationship between chlorophyll aggregation behavior and thermal stability in aqueous systems, which is an important prerequisite for subsequent validation and application in real food matrices.