Local Dynamics During the Mixing of Saliva with a Model Colloidal Food

The events occurring during the spontaneous mixing of an okra mucilage-based model liquid food with saliva were recorded, with a focus on the local dynamics of colloidal particles contained therein. An okra mucilage containing fluorescent microsphere probes (assuming the role of model emulsion droplets), was brought into contact with reconstituted saliva on the welled slide of a confocal microscope. The movement of the probes at the saliva–mucilage interface and in the bulk mucilage has been recorded over periods of 60 min. Data have been obtained on the total mobility of individual model droplets, their diffusion coefficients, and the local viscosities, providing information on the dynamics of processes which occur during the oral processing of colloidal liquids. The role of osmotic pressure gradients on the spreading of the droplets into saliva is discussed in relation to the microrheology data.