A Deakin University study has found that caffeine does not have the flavour enhancing qualities claimed by soft drink manufacturers.

The study by Dr Russell Keast and Dr Lynn Riddell of Deakin University’s Faculty of Health, Medicine, Nursing and Behavioural Sciences, in Melbourne, Australia, found that caffeine had no effect on the flavour of soft drinks.

Caffeine is a widely consumed, mildly addictive chemical that occurs naturally in coffee, tea and chocolate, but is an additive to soft drinks—mostly cola flavoured drinks.

"Soft drink manufacturers claim caffeine is added as flavouring," Dr Keast said.

"We found no flavour based rationale to include caffeine in soft drinks, so why would beverage manufacturers include caffeine in their product formulations?"

There are serious public health reasons to remove caffeine from sugar-sweetened soft drinks, Dr Keast said.

"The level of caffeine found in 500ml of soft drink is enough to trigger the types of psychological and physiological responses that lead to addictive behaviour," he explained.

"A child who consumes a sugar sweetened soft drink not only enjoys the sweet taste, but also associates the flavour with the positive effects of caffeine. Caffeine’s influence on the body diminishes over 6-12 hours and the child would then consume another caffeinated soft drink to get a boost.

"This is of particular concern as consumption of soft drinks has been linked with adolescent and childhood obesity."

In the study, highly trained panellists tasted a caffeinated and non-caffeinated cola drink as well as caffeinated and non-caffeinated sweet solutions.

While the tasters were able to detect subtle differences in flavour when caffeine was added to a variety of sweet solutions, they were unable to detect any differences in the flavour of the cola soft drink.

"We believe the tasters inability to notice any difference in the taste of the caffeinated and non-caffeinated soft drink is due to multiple ingredients in the soft drink that effectively mask any subtle effects caffeine may have on flavour," Dr Keast said.

"These results put a serious question mark on whether an addictive agent such as caffeine should be an additive in sugar-sweetened soft drinks marketed to children and adolescents."

The results of the study have been published in the latest issue of the international journal Appetite.