Researchers from Unilever R&D Vlaardingen, The Netherlands, and the University of Manchester, UK, investigated whether, and how, the energy content of a yoghurt drink affects its liking and reward value over repeat consumption.
“Specifically, we investigated whether yoghurt drinks consumed in a high energy need state would lead to preference of the high energy over the low energy version,” said the authors, led by Elizabeth Zandstra of Unilever R&D.
“The results indicate that we succeeded in conditioning preference for a delayed (energy) reward: participants chose the high energy yoghurt drink significantly more often over the low energy yoghurt drink,” they said.
The authors added that the study also provides “a new approach to the conditioning paradigm (cueing energy via a coloured label instead of flavour) and includes a new and important measures in this research area (preference instead of liking).”
Zandstra and colleagues reported that 44 participants were given either a high or low energy yoghurt drinks (255 kcal or 57 kcal per 200 ml serving, respectively) every morning for two weeks, with five exposures to each yoghurt drink on alternate days.
The high and low energy yoghurt drinks were paired with two coloured labels, either blue or pink, with the pairings fully counter-balanced.
“Participants were not aware that the drinks differed in any way, except that one drink had a blue label, and the other a pink label,” said the authors.
In the third test week, participants were given a free choice of either consuming the pink or the blue labelled yoghurt drink.
The researchers found that in the third week participants chose the high energy drink significantly more often over the low energy drink, “suggesting a conditioned preference for a delayed (energy) reward.”
“Clear and pronounced effects were found for the behaviour measure preference: participants chose the high energy yoghurt drink significantly more often over the low energy yoghurt drink,” said Zandstra and co-workers.
“These findings provide further evidence for energy based learning in human adults,” they added.