From molecular binding to mouthfeel: Oil saturation controls oral lubrication through interfacial protein films.

The oily mouthfeel is a critical sensory governed by the lubrication of saliva emulsions during oral processing, but the molecular mechanisms remain unclear. This study investigated this mechanism by using a saturated oil (Medium-chain triglyceride, MCT), a monounsaturated corn oil (CO), and a polyunsaturated linseed oil (LO). LO (polyunsaturated) exhibited high-energy binding to salivary mucin, inducing significant protein denaturation. These unfolded proteins formed deficient interfacial films with low viscoelasticity, causing rapid coalescence and lubrication failure. Conversely, MCT (saturated) showed moderate binding that preserved mucin structure, enabling the formation of elastic interfacial films. These stable emulsions provided effective lubrication via a ball-bearing mechanism. This structure-function relationship demonstrated that oil composition regulated oral lubrication by tuning conformation of salivary protein at the interface, which offered a molecular basis for oiliness design.