MUFFIN

Flavor perception is one of the factors guiding food consumption. Flavor is mainly perceived by the chemical senses of taste and olfaction (aroma retro-nasal perception), but also by the “trigeminal senses”, which can detect for example astringent molecules. The effect of saliva and salivary proteins on flavor perception is increasingly recognized. More specifically, recent studies suggest that the mucosal pellicle, a layer of salivary proteins bound to oral mucosa, could be involved in flavor perception. For example, a study on astringency concluded that salivary proteins in solution inhibit the mouthfeeling of astringency, which is mediated, at least in part, by salivary proteins adhered to buccal cells. However, the molecular interactions occurring between the proteins of the mucosal pellicle and flavor compounds are still not thoroughly understood and studies dedicated to that topic are lacking. MUFFIN proposes to elucidate the molecular basis of interactions between food constituents and the mucosal pellicle, focusing on two sensory modalities: astringency and aroma perception. Astringency is defined as a complex sensation due to shrinking, drawing, or puckering of the epithelium, resulting from exposure to substances such as tannins. It is generally accepted that the interactions occurring between salivary proline-rich proteins (PRP) and tannins play a role in this sensation. The mechanism could involve interactions between the PRP•tannin complexes, after aggregation, and the proteins belonging to the mucosal pellicle. Another hypothesis postulates that PRP have a protective role toward tannins, decreasing the astringency sensation by protecting the mucosa from tannins. The oral mucosa may also be involved in persistence of aroma in the mouth, a sensory phenomenon for which no mechanistic explanation is available. It has been reported that free salivary proteins, such as mucin and a-amylase, can affect the release of aroma compounds. However, salivary proteins in solution are swallowed at each deglutition. Therefore, we propose that the aroma persistence in the mouth could be due to molecular interactions between the bound proteins of the mucosal pellicle and aroma compounds. MUFFIN proposes to develop a model mucosa allowing in vitro experiments to gain a deeper understanding of these molecular interactions. This basic project will bring crucial information on the role of the mucosal pellicle in flavor perception. More particularly, MUFFIN should provide a unique opportunity (1) to develop a well characterized model of mucosa composed of a realistic salivary protein layer anchoring onto an epithelium; (2) to determine the role of the mucosal pellicle into aroma release and persistence in mouth; (3) to characterize the impact of tannins on the structure of the salivary film, the role of the salivary PRPs in the protection of the mucosa; (4) to characterize the effect of tannins on the ability of the mucosal pellicle to interact with aroma compounds and (5), finally, to investigate the effects of inter-individual variations in the composition and the structure of the mucosal pellicle on its interactions with flavor molecules. This ambitious project takes into account two different modalities of flavor (astringency, aromatic perception) and their interaction, also the inter-individual physiological and sensory variability. Therefore, it will provide a global vision of the role played by the mucosal pellicle on flavor. To achieve its objectives, MUFFIN proposes a multidisciplinary approach associating expertise in cell culture, protein biochemistry, imaging technics (SEM, TEM, biphotonic microscopy, AFM, HS-AFM), analytical chemistry (PTR-MS and GC-FID) and chemoinformatics (QSPR approach). Moreover, MUFFIN is a fundamental research project, which will give the opportunity to a young researcher to develop his own research thematic and lead his own research group.