“Oral processing, or how we eat, includes the first bite; break down then bolus formation; bolus break down; then swallowing. Sensory perception is the science of capturing the data, or what we perceive as we eat,” explained Mary Jean Cash, R&D, Food & Beverage Applications, for Ashland Specialty Ingredients. 

There are perceptions at each point of oral processing. Temporal Dominance of Sensation (TDS), or the dominant perception, occurs at a specific point in the oral process. In consuming liquids foods across the oral cavity, (Sonne, et al, 2014) found that viscosity, yield stress and surface dominated. Stokes, et al, 2013, found that bulk and surface properties dominated. Other fields include mechanics, rheology, tribology and granulation. 

“When taking that first bite or sip, firmness or thickness of the food or beverage is identified,” said Cash. “The sensory perception of thickness can be measured instrumentally with a Bostwick consistometer and correlated with appropriate consistency classification for dysphasia patients, for example.” 

Viscosity measurements also can be correlated with the sensory perception of thickness. 

Texture analysis imitates mastication, giving a Texture Profile Analysis (TPA) for bulk properties of a food or beverage. Auditory devices, coupled with TPA, can give a correlation with crispiness. Sensory perceptions of firmness, hardness, crispiness, springiness and cohesiveness can be correlated with texture analysis measurements, as well.

“Particle size and hardness also have influence on mouthfeel, or the sensory perceptions grittiness or creaminess,” added Cash. 

Tribology is the study of interacting surfaces in relative motion; when eating, surfaces include the food, oral cavity, tongue and teeth. Saliva is a good boundary liquid in the process. Tribology has many factors, including velocity, lubrication and surface smoothness—all influenced by the rheology of saliva compounds, food particle size, and shape, fat droplet size, pH and more. 

Measurements for tribology include load force, constant speed, variable speed and temperature. Properties measured include creaminess, mouthcoating and astringency. Tribology data with rheological data correlates well to sensory data. 

In summary, Cash stated that the dynamics of oral processing are challenging. But there are approaches to measuring texture and mouthfeel, which include imitative techniques, empirical methods and fundamental mechanical properties that can provide useful information. Sensory science can capture very complex data over time of the oral processing experience, and instrumentation has been shown to correlate to specific points during oral processing. Cash advised that to capture the desired sensory information, strategies must include correlation of instrument fitters, settings, materials, sample history and time. 

The power of applied chemistry can transform the efficacy, usability, allure, integrity and profitability of products. 

“The Use of Instrumental Analysis in Evaluation of the Texture of Beverages,” Mary Jean Cash, R&D, Food & Beverage Applications for Ashland Specialty Ingredients, 302-995-3191, mcash@ashland.com. 

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