Application of CoQ10-loaded gSP-CS double-layer emulsion in milk: Impacts on quality and storage stability

The application of coenzyme Q 10 (CoQ 10 ) in liquid milk remains challenging due to its poor water solubility and chemical instability. Although CoQ 10 -loaded emulsions have been extensively studied, a critical knowledge gap persists: how exogenous emulsion droplets coexist with native milk fat globule membranes (MFGM) in real milk systems, and whether such addition compromises milk quality and storage stability remain largely unknown. To address this, we incorporated CoQ 10 -loaded glycosylated soybean peptide-chitosan (gSP-CS) double-layer emulsion into milk and systematically evaluated these unresolved issues. Key findings include: CLSM visualization, for the first time, revealed that exogenous droplets uniformly coexisted with native MFGM at 5% addition, but induced MFGM aggregation and disruption at 20%. Notably, CoQ 10 retention exceeded 60% at 5% emulsion after 21 days at 4 °C, whereas only 25.2% was retained at 20%. Based on comprehensive assessments of stability, sensory properties, and retention, an addition level of 5–10% is recommended. This study fills the knowledge gap regarding the application of gSP-CS double-layer emulsions in real dairy matrices and provides critical data for formulating CoQ 10 -fortified functional milk products.