Revealing the interaction between sweetness and sourness

21 December 2021

Sugar versus sugar-free? Consumers judge hard when it comes to sugar reduced or sugar free products, and there is a reason why it is so complicated to maintain the original taste in these products.

PhD student Jonas Yde Junge from Department of Food Science, Aarhus University investigates taste interactions between sweetness and sourness in beverages. Taste interactions occur when two tastes either enhance or suppress each other. Sweetness and sourness suppress each other, but where and how does the interaction take place? That is what Jonas Yde Junge is looking into.

The brain, the tongue or chemistry

Overall, he examines three mechanisms for interaction: a cognitive mechanism in the brain, an interaction in the dissolution, and an oral interaction happening between the molecules and the taste receptor in the tongue.

‘It is interesting to know the precise mechanism, because it can affect the way we compose beverages. If you change the composition, but maintain the taste, you have to be aware of what molecules you use for sweetness, if it is an oral mechanism. If it is a cognitive mechanism, it does not matter how you achieve the sweetness, because the interaction occurs in the brain,‘ says Jonas Yde Junge.

45 days with taste experiments

Jonas Yde Junge has just finished what he calls the core study of his PhD project. The study has taken place in Denmark, and for one and half month he has conducted tests with 55 persons. Each participant undergoes two hours of tests, and the study is therefore rather time-consuming compared to other studies in the research field.

‘For this study I was inspired by 40 year old studies, where researchers have used the tongue as control for itself. The split-tongue method exploits the fact that the two sides of the tongue is functionally identical,’ explains Jonas Yde Junge.

In his study the participants receive a sweet solution on one side of the tongue and a sour solution on the other. Later they receive a mixed solution on both sides of the tongue.

The setup makes it possible to reveal whether the taste mechanism is mainly a cognitive mechanism, which is the case if the participants have the same taste perception in the subsequent experiments, or whether it is mainly a chemical interaction or an oral interaction related to taste receptors or taste cells.

Jonas Yde Junge has worked on the equipment and set-up for almost a year, and it was a milestone, when the study was closed in November, and he could begin the final sprint of the project. He expects to hand-in his PhD project mid 2022.