Food grade Boger fluids for sensory studies

The effect of shear viscosity on taste and mouthfeel perception has been extensively studied; however, the effect of extensional viscosity on sensory perception has been mostly neglected. This may be important as in-mouth processing is complex and probably best described as a superposition of shear and extensional flow characteristics. Fluid mechanics researchers interested in separating elastic effects from viscous effects use Boger fluids and this approach was adopted here to investigate the effect of fluid elasticity on sensory perception. For the first time, two food grade Boger fluids based on glucose syrup and aqueous solutions of maltodextrin as solvents and xanthan gum as high molecular weight polymer were formulated. The elasticity of the Boger fluids was characterised in rotational shear rheometry, in a filament break-up device and in microcontraction flow. Saltiness perception and mouthfeel of the Boger fluids and samples corresponding to the respective solvent were analysed. Surprisingly, there were no significant differences. Hypotheses attributing this finding to the intrinsic properties of the samples are discussed. A major study would be required to gain in-depth understanding of the sensory properties of these fluids as their flow properties are very different from typical liquid foods.