Assessing Lipid Coating of the Human Oral Cavity after Ingestion of Fatty Foods

The coating on the oral surface plays a significant role in mouthfeel perception, which is an important attribute governing perception of reduced-fat or low-fat food products. The aim of this work was to develop efficient methods to quantify the coating of the lipids covering the oral surface after ingestion of fatty foods. Three different approaches were assessed to investigate the in-mouth behavior of fluid foods in a subject. A first approach determined the mass of lipids retained in the oral cavity by rinsing it out. A second approach evaluated the thickness of the lipid coating on the tongue by fluorescence measurement using a dye incorporated in oil. Finally, a third approach measured local lipid thickness by adsorption of the lipids on a filter paper. All applied methods showed results in the same range. The thickness of the lipid coating was on average between 5 and 32 µm. The total lipid recoveries obtained by controlled rinses from the oral cavity were approximately 96 and 50% for single filter paper. A fast, simple, and quantitative method was developed to measure the thickness of the lipid coating on an oral surface after ingestion of fatty foods. This work presents the potential of the method to investigate in-mouth distribution and residues of lipids and establishes new avenues to study in-mouth behavior of food components and its influence on the sensory perception.