Water–triglyceride interfaces limit permeability and diffusion of aroma molecules in butter

Insight into the dynamics of aroma molecules in bulk phases and at water–triglyceride interfaces is crucial for elucidating the aroma release mechanisms in complex dairy products such as butter. This study employs classical, all-atom molecular dynamics simulations with umbrella sampling to investigate the energetics and kinetics of key aroma-active compounds, including diacetyl, (Formula presented.) -decalactone, and butyric acid, at interfaces of 1,3-dipalmitoyl-2-oleoylglycerol (POP) in water. The chemical properties of aroma compounds, including polarity, hydrogen bonding, and van der Waals interactions, play a pivotal role in their interaction with interfacial molecules, resulting in unique profiles of the potential of mean force and diffusivity. In particular, (Formula presented.) -decalactone preferentially resides at the interface and accumulates in the triglyceride phase. Aroma permeability through the complexly organized water–triglyceride interface significantly decreases from (Formula presented.) -decalactone to butyric acid, with a less pronounced reduction for diacetyl. Surprisingly, this trend in aroma permeability at interfaces does not coincide with trends in aroma diffusion within both pure bulk phases. This discrepancy is attributed to local, heterogeneous molecular structuring at water–triglyceride interfaces, impeding the interfacial permeation processes and leading to local aroma confinement. Practical Application: Employing a water–POP interface as a case study, the methodology investigates aroma compound diffusion within bulk phases, delineating limitations in aroma permeability in dairy products with extended water–triglyceride interfaces. This is a substep in the aroma release process, contributing to the interpretation of perception studies by sensory panels in human sensory experiments and fostering a deeper understanding of the intricate dynamics inherent to individual compounds.