Repeated exposures may offer better measure of consumer liking: Study

By Nathan Gray

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Single exposure tests to predict long-term consumer preferences may be less reliable than previously thought, according new research

The study, published in Food Quality and Preference​, found that repeated exposure and preference testing of sports drinks with different subtle changes (in the form of different acidulants) led to changes in preference when 128 consumers evaluated the drinks over a 14 day period.

The authors, from the University of Pretoria, South Africa, said that the findings “challenge the validity of sensory evaluation test strategies that rely on single exposure testing to predict long-term consumer preferences.”

“It is possible that subtle differences in the taste profiles of the sports drinks with the different acidulants became more evident after repeated exposure and therefore influenced liking,”​ said the researchers, led by senior author Dr Henriette de Kock from the Department of Food Science, at the University of Pretoria.

Subtle changes

“In the food industry it is often necessary to make small changes to the formulation of a well-known food product,”​ said the authors, who explained that such changes may influence long term consumer acceptance of the product.

For example, a decision to change from using citric acid to another acidulant in a sports drink can be a major decision for a manufacturer, they said.

Previous studies have shown that a subtle difference in the taste profiles of similar food products may be noticeable only after repeated tasting.

The new research tested this by determining whether repeated exposure to a sports drink with different acidulants (including malic acid, tartaric acid, fumaric acid and Fruitaric acid) would lead to changes in long-term acceptance and preference – referred to as hedonic adjustment.

“The question asked during this investigation was whether consumers will notice a difference in a sports drink if citric acid was replaced with another acidulant and if they do, whether it would affect preference,”​ explained the researchers.

Study details

The authors used a ranking test, which enabled them to measure preference changes between the products without indicating other differences. They explained that this method is powerful when comparing formulations with only slight variations.

An initial sensory group of 10 trained panellists compared the sports drink containing the different acidulants to the original drink containing citric acid.

The trained panel reported no differences in the respective ratings for malic, tartaric, fumaric and Fruitaric acid sports drinks compared with the drink containing citric acid.

After the initial sensory panel testing, the researchers tested preference after repeated exposures on 128 volunteers over two weeks.

de Kock and her co-workers noted that product exposure influenced the preferences of consumers. They reported that products preferred initially became less preferred after 14 days exposure, and visa versa.

“Interestingly, no significant difference in preference was noted during the second laboratory evaluation … ​[But] the results from the third laboratory session … confirmed a clear shift in consumer preferences for the sports drinks,”​ said the authors.

They noted that the initial single exposure taste test was not predictive of consumer preferences after repeated exposure.

Source: Food Quality and Preference
​Published online ahead of print, doi: 10.1016/j.foodqual.2011.01.003
Would repeated consumption of sports drinks with different acidulants lead to hedonic adjustment?”
Authors: M. Kinnear, H.L. de Kock

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