Using low-field nuclear magnetic resonance to investigate the effect of composition, mechanical treatments, and storage on the stability of emulsions
Sara Aghajanzadeh, Ali Asghari, Christophe Cordella, Seddik Khalloufi
Abstract
This study investigates the application of low-field nuclear magnetic resonance (LF-NMR) to evaluate emulsion stability, focusing on formulation, mechanical treatments, and storage. The results showed that Emulsion 2 (water: 72.73 %, oil: 18.18 %, and egg yolk: 9.09 %) showed 4.68 % decrease in the longest peak relaxation time (T 24 ) and 14.58 % reduction in T 24 peak ratio than Emulsion 1 (water: 85.71 %, oil: 9.52 %, and egg yolk: 4.76 %). Mechanical treatments (high-speed mixing and high-pressure homogenization) increased T 24 peak area ratio (>64 %) due to particle size reduction (<200 μm) and enhanced stability. Conversely, centrifuging the mechanically treated samples increased T 24 peak ratio (Emulsion 1: 61.95 %, Emulsion 2: 21.88 %), indicating phase separation. After one day of storage, single-component relaxation time (T 2w ) doubled, reflecting weaker hydrogen bonding. A peak ratio's relationship with storage time (R 2 > 0.99) was developed to predict emulsion stability. This study demonstrates LF-NMR's potential for predicting phase behavior and optimizing emulsion formulations and processing technologies. • LF-NMR revealed interactions, mobility, and stability in liquid systems. • T 2 revealed proton mobility, interactions, and water/lipid states in the systems. • T 2w raise showed weaker binding forces and higher mobility in the aqueous phase. • LF-NMR detected phase separation affected by formulation, treatments, and storage. • LF-NMR is a fast, non-destructive tool for predicting phase behavior and optimizing processes.