Oral processing of food involves a chain of sensory and neural events in which a food’s physical structure elicits oral sensations and subjective valuations that guide eating behavior. For example, foods high in sugar and fat typically produce a characteristic flavour in the form of a sweet taste and thick, smooth texture (‘mouthfeel’). These sensory signals are thought to contribute to the reward value of food, to the near-universal preferences for foods high in sugar and fat, and to unhealthy eating behavior and the development of obesity. This talk will review our recent findings from behavioural and neurophysiological experiments in monkeys and humans showing that (i) nutrients and sensory food qualities constitute biologically critical rewards that influence human-typical sophisticated economic food preferences (Huang, Sutcliffe, and Grabenhorst, 2021, PNAS); (ii) nutrient components of food rewards guide reinforcement learning and decision-making (Huang and Grabenhorst, 2023, Journal of Neuroscience); (iii) two key oral-texture parameters—the coefficient of sliding friction and viscosity—are processed in reward structures of the human brain in a manner that predicts individual differences in fat preference during naturalistic eating (Khorisantono et al., 2023, under review). Of particular interest was the finding that the coefficient of sliding friction, measured in our experiments from the interactions between fatty liquid foods and real oral surfaces (pig tongues), partly mediated the effect of a food’s fat content on subjects’ economic food preferences and brain reward responses. Our findings have implications for the design of foods that have both healthy nutrient composition and attractive oral-texture properties that mimic the reward value of dietary fat.

This work was funded by the Wellcome Trust and the Royal Society.