28 Jun 2019

A food's texture will determine whether a food is eaten, rejected or enjoyed with some people experiencing texture sensations more than others because their tongues can perceive particle sizes, new Penn State research suggests.

The Sensory Evaluation Center in the College of Agricultural Sciences at Penn State researched 111 volunteer tasters who had their tongues checked for physical sensitivity and then were asked their perceptions about various textures in chocolate.

"We've known for a long time that individual differences in taste and smell can cause differences in liking and food intake -- now it looks like the same might be true for texture," said John Hayes, associate professor of food science. "This may have implications for parents of picky eaters since texture is often a major reason food is rejected."

The perception of food texture arises from the interaction of a food with mechanoreceptors in the mouth, Hayes noted. It depends on neural impulses carried by multiple nerves. Despite being a key driver of the acceptance or rejection of foods, he pointed out, oral texture perception remains poorly understood relative to taste and smell, two other sensory inputs critical for flavor perception.

Researchers tested whether there was a relationship between oral touch sensitivity and the perception of particle size. They used a device called Von Frey Hairs to gauge whether participants could discriminate between different amounts of force applied to their tongues.

When participants were split into groups based on pressure-point sensitivity -- high and low acuity -- there was a significant relationship between chocolate-texture discrimination and pressure-point sensitivity for the high-acuity group on the center tongue. However, a similar relationship was not seen for data from the lateral edge of the tongue.

Chocolate texture-detection experiments included both manipulated chocolates produced in a pilot plant in the Rodney A. Erickson Food Science Building and with two commercially produced chocolates. Because chocolate is a semi-solid suspension of fine particles from cocoa and sugar dispersed in a continuous fat base, Hayes explained, it is an ideal food for the study of texture.

"These findings are novel, as we are unaware of previous work showing a relationship between oral pressure sensitivity and ability to detect differences in particle size in a food product," Hayes said. "Collectively, these findings suggest that texture-detection mechanisms, which underpin point-pressure sensitivity, likely contribute to the detection of particle size in food such as chocolate."

This study sets the stage for follow-on cross-disciplinary research at Penn State, Etter believes. She plans to collaborate with Hayes and the Sensory Evaluation Center on studies involving foods beyond chocolate and older, perhaps less-healthy participants to judge the ability of older people to experience oral sensations and explore food-rejection behavior that may have serious health and nutrition implications.