Washington: Not just the taste and smell, but food's texture also affects whether it is eaten, liked or rejected, recent findings suggest. As part of the study, researchers found that people are better at detecting even minor differences in consistency because their tongues can perceive particle sizes.
The research included 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.
According to the researchers, these findings, published in Scientific Report, may have implications for parents of picky eaters since the 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 flavour perception.
One argument is that texture typically is not noticed when it is within an acceptable range, but that it is a major factor in rejection if an adverse texture is present, explained Hayes. For chocolate specifically, the oral texture is a critical quality attribute, with grittiness often being used to differentiate bulk chocolate from premium chocolates.
"Chocolate manufacturers spend lots of energy grinding cocoa and sugar down to the right particle size for optimal acceptability by consumers," he said. "This work may help them figure out when it is good enough without going overboard."
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 centre 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.
Researchers suggest that 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.