Foods that are more -- or less -- delicious than we expect can also cause mood changes, according to a recent study.

Researchers found that eating vanilla yogurt made people feel happy. They also found that yogurts with lower fat content gave people a stronger positive emotional response, Bel Marra Health reported.

"We were surprised to find that by measuring emotions, we could get information about products independent from whether people like them," Dr. Jozina Mojet, lead author of the study, said in a statement. "This kind of information could be very valuable to product manufacturers, giving them a glimpse into how we subconsciously respond to a product."

For the study, researchers collected and analyzed data from more than 70 people, The Blaze reported. They used a new method called an emotive projection test to determine the effect of different yogurts on people's moods. The test involved showing study participants photographs of other people and asking them to rate the people in the photographs on six positive and six negative traits. The idea behind the test is that people project their emotions onto others, so their judgment of others could indicate their own mood.

The participants were split into three groups that were each given a par of yogurts to taste. The pairs of yogurts were of the same brand and were marketed in the same way, but had different flavors or fat content. The team then tested their emotions using four methods, including the new emotive projection test.

The results revealed that liking or being familiar with a product had no effect on a person's emotion. However, changes in whether they liked it after tasting the yogurt did: being pleasantly surprised or disappointed about the food influenced people's moods.

"We were looking for a valid, quick and not too expensive and time-consuming method to measure the emotions or mood changes evoked by food," Mojet said. "I strongly believe that sensory and consumer research should be conducted in an ecologically valid way. This sort of implicit method can reveal the complex interactions between the different factors involved in a situation, which, based on his or her memory and expectations, is given meaning by the person under investigation."

The findings are detailed in the journal Food Research International.