In a surprising turn of events, research has shown that people often prefer fleshy fat yogurt or ice cream over lighter alternatives. However, it’s not just the taste that’s responsible for this preference – it’s also the addictive mouthfeel of high-fat products.
A study conducted by brain researchers at Oxford University found that the brain area responsible for sensations and the attractiveness of food, known as the orbitofrontal cortex, becomes more active when recognizing fatty foods. The study focused on the melting oiliness of the food, which reduces friction as it slides against the tongue and walls of the mouth.
To test this theory, researchers prepared vanilla-flavored milkshakes with varying fat and sugar content. They also obtained pig tongues from a local butcher to measure sliding friction in conditions similar to the human mouth. The results showed that friction decreased according to the fat content of the shake.
Next, more than 20 test subjects tasted different milkshakes and were asked how much they were willing to pay for more. Their brains were imaged using functional magnetic resonance imaging (fMRI) while they tasted their milkshakes to see if there were any correlations between composition and pleasure levels in their brains.
The results showed that differences in composition and pleasantness were reflected in reactions from the orbitofrontal cortex. The preference was partly explained by mouthfeel associated with sliding friction, which affects people’s food choices. For example, when participants could choose between three curries with different fat content for lunch without knowing they were being observed, those whose orbitofrontal cortex reacted strongly to greasy mouthfeel in previous experiments chose fattier meals more frequently than those who did not show such a reaction.