Oral processing and matrix composition affect aroma release and particle size distribution after consumption of coffee-creamer emulsions.

Context and objectives: In humans, the main events that contribute to in-mouth emulsion breakdown are shear forces due to tongue movements and action of saliva. To date, most of the studies on the field were conducted on model emulsions and little is known about creamer emulsion and in particular hot coffee/creamer emulsions. In this context, the objective of the present work is to better understand how human oral physiology may govern the in-mouth breakdown of coffee-creamer beverages with consequence of food bolus structure and aroma release and to focus on saliva role and composition in particular. Methodology: The work was conducted on 7 coffee-creamer matrices differing by the amount of salt, fat and texturing agents. In vivo aroma release, mouth coating and bolus structure and moistening were followed on 12 subjects with highly variable saliva composition. Eight aroma compounds (butanone, 2-methylfuran, 3-methylbutanal, furfural, pyridine, acetoin, 2,3-pentanedione, diacetyl) were followed in vivo and online by PTR-ToF-MS. Matrix coating was evaluated thanks to fluorimetric methodology. Particle size distribution (PSD) of the food bolus was evaluated with laser granulometry. Saliva properties (viscosity, composition) and oral volume were also measured in each panellist. Statistic was performed through multivariate and anova analysis. Results: In vivo aroma release was mostly explained by oral physiology, the most influenced aroma being diacetyl, 2,3-pentanedione & 3-methylbutanal. Aroma persistence is mainly linked to oral volume, salivary flux and composition (proteolysis). Aroma release depends also on coating: the higher the coating, the higher the aroma release and conversely for aroma persistence. Mouth coating depends on oil droplet flocculation in the bolus, bolus moistening, salivary flux and oral volume: the higher these parameters, the higher the coating. At last, bolus structure (PSD) is matrix dependant and not subject dependant except for 1 matrix differing by its texturing agent. To conclude in vivo aroma release after consumption of coffee-creamer matrices is mainly influenced by the subjects and in particular salivary composition while food bolus structures is principally driven by the product formulation. These results can help to formulate coffee creamer matrices better adapted to oral physiology and thus to consumer liking.