Writing in the Journal of Texture Studies, researchers from the University of North Carolina, USA, Liverpool John Moores University, UK, and Unilever, investigated the links between the physical attributes and sensory perceptions of fluids. Led by Steve Guest, from the University of North Carolina, the researchers explained that when developing new fluid based products, it is important to understand how consumers perceive such fluids as this will affect overall acceptance of products.
“These relationships allow early insights concerning how one might formulate a product,” said the researchers.
The authors explained that unlike solid foods, very little is known about the linkage between the physical properties of fluids and how they are perceived.
“Upon perusing the tactile perception literature, it would be easy to conclude that the world of touch consists almost entirely of interactions with solid objects. Quite clearly, this is not the case; we interact with fluids, gels and semisolids on a daily basis ... in our handling and ingesting of foods and drink,” wrote Guest and his team.
They said that a number of studies have reported that the most important tactual characteristics of solid materials are well described by three or four perceptual dimensions: roughness, softness, elasticity or ‘springiness’ and slipperiness.
“In contrast to solid materials, little research has been undertaken to identify the perceptual attributes that describe tactile interactions with fluids,” they noted, adding that it is clear from the limited research available that the important perceptual attributes of fluid stimuli “are indeed quite different from those of solid stimuli.”
Guest and his colleagues physically characterised 15 fluids with diverse rheologies, before perceptual ratings of 27 ‘sensory’ attributes – such as ‘oily’ – and 14 ‘emotional’ attributes – like ‘arousing’ – were made by 20 participants.
The team then broke down the physical analysis into the approximate factors: friction, normal vibration, and tangential vibration; the sensory attributes into: watery, textured, slick, silken and viscous factors; and the emotional attributes into: pleasant, sensual and harsh.
They reported that ‘emotional’ factors like pleasant and harsh were related to the sensory attributes textured and silken.
“Fluids perceived as more watery elicited greater normal and tangential vibration and less friction, whereas high viscous scores were associated with lower vibration factor scores and increasing friction,” they noted.
The authors said that future research should collect mechanical event and psychophysical data concurrently, from the same participants.
“Consequently we expect relationships between the objective and subjective data to be rendered even more clearly,” they explained.
Source: Journal of Texture Studies
Published online ahead of print, doi: 10.1111/j.1745-4603.2011.00318.x
“Physics and tactile perception of fluid-covered surfaces”
Authors: S. Guest, A. Mehrabyan, G. Essick, N. Phillips, A. Hopkinson, F. Mcglone