Differential hedonic, sensory and behavioural changes associated with flavour–nutrient and flavour–flavour learning.

Abstract

Flavour–flavour and flavour–nutrient associations can modify liking for a flavour CS, while flavour-flavour associations can also modify the sensory experience of the trained flavour. Less is known about how these associations modify behavioural responses to the trained CS. To test this, 72 participants classified as sweet likers according to their response to 10% sucrose were divided into five training conditions with a cranberry+orange flavour CS. In the flavour–flavour condition, participants consumed the target CS in a sweetened, low energy form (7 kcal, aspartame as sweetener), with energy but no sweetness added in the flavour-nutrient condition (159 kcal, energy as maltodextrin) and both energy and sweetness in a combined flavour–flavour, flavour–nutrient condition (159 kcal with 10% sucrose). Control groups controlled for exposure to the CS, and repeat testing. Training was conducted in a hungry state on four non-consecutive days. To test for acquired changes in evaluation and intake, the flavour CS was processed into a low-energy sorbet, which was evaluated and consumed ad libitum on two test days before and after training. Liking for the flavour CS increased only in the sucrose sweetened condition, but intake increased significantly in both high-energy conditions. In contrast, rated sweetness of the sorbet increased in both the sucrose–sweetened and aspartame–sweetened conditions. These findings suggest that liking changes are maximal when flavour–flavour and flavour–nutrient associations co-occur, but that behavioural changes are specific to flavour-nutrient associations. These data also confirm that hedonic and sensory evaluations occur through independent learning processes.