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Scientists study consumers’ detection threshold

Using milk and dark chocolate, food scientists find consumers don’t always dislike a food because they detect something different


University Park, Penn. – Food scientists at Penn State have found that consumers who love milk chocolate are much less accepting of bitter tastes.

In a test of bitterness rejection levels in chocolate, people who prefer milk chocolate quickly detected and disliked milk chocolate with a bitter substance added to it.

Fans of dark chocolate, however, had a significantly higher tolerance to the added bitterness.

“In some cases, you may be able to detect a change in the taste of your food, but that might not necessarily lead to disliking the product,” says Meriel Harwood, a food science graduate student.

“However, almost immediately, people who preferred milk chocolate indicated they tasted something different and they didn’t like it.”

Experiment, findings

The researchers divided a group of participants into two groups based on their self-identified preferences in chocolate, says Penn State.

A total of 43 people told researchers they preferred milk chocolate, and 42 said they preferred dark chocolate.

Participants tried a series of pairs of dime-size chocolate samples. In each pair, one sample contained sucrose octaacetate (SOA), a bitter-tasting substance, and the other did not. In each successive pair, the next samples contained increasing amounts of SOA.

The milk chocolate group quickly rejected the samples with SOA, while the dark chocolate group did not, says Harwood. The dark chocolate group had a rejection threshold more than 2.5 times the rejection threshold level of those who prefer milk chocolate.

Harwood says that tests of rejection thresholds in food may be a simpler and more direct way to test food acceptability rather than measuring when the consumer can taste something different – detection thresholds.

Detection threshold

The detection threshold test is one of the most common taste tests used in sensory science and is usually paired with affective, or consumer, testing to determine preferences.

People do not always dislike a food because they detect something different, even if that difference may be considered a defect or undesirable attribute, explains Harwood.

“There may be a disconnect between preferences and the ability to detect tastes, like bitterness,” says Harwood. “In other words, using detection threshold tests may not predict consumer acceptability.”

Harwood adds that rejection threshold tests may lead to cost-savings for the food industry.

Cost-savings for processors

Rather than disposing products that are thought to be undesirable and wasting costly materials, researchers could use rejection thresholds to find out whether consumers will object to the taste of a product.

Food manufacturers may also be able to use alternative ingredients, such as sugar or salt replacements, if they can first identify a rejection threshold level for those ingredients in products. This could give product developers more versatility when they create recipes.