I asked ChatGPT what someone should do if they were offered a lemon for breakfast. The AI replied: “When life hands you lemons, throw them back and demand chocolate.” While most of you may agree with the AI chatbot, some people actually relish intense sour food items and will accept the lemons without throwing any tantrums.

The assumption is that adults generally dislike sour food. This is why while most studies in the past focused on people’s responses to sweet and salty food items, sourness and sour-likers have been largely ignored.

However, a new study involving participants from Italy and the US reveals that one in eight adults are in fact “sour likers”. This select group of people enjoy foods and drinks with high levels of tartness. Scientists have previously studied children’s responses to sour food items, but this is the first time enjoyment for sourness has been explored in the case of adults.  

“Within the traditional evolutionary approach/avoidance framework, sour taste is generally assumed to be a negative taste quality. This is the first time it’s been convincingly shown that there is a segment of adults who like strongly sour things,” the researchers note.

The cross-cultural citric acid experiment 

To test the liking for sourness among adults, the researchers conducted an interesting experiment. They recruited participants from the US and Italy, two countries with very different food cultures.

For instance, the most popular beverage in the US is coffee (next to bottled water), but for Italians, it is wine. When it comes to street food, Americans tend to favor pretzels, and hot dogs, while Italians savor pizza, and arancini (stuffed rice balls). 

Keeping many such cultural differences in mind, the researchers asked 143 adults in the US to consume and rate water samples with different levels of citric acid. A similar experiment was conducted with 350 adults in Italy where they drank and rated pear juice samples with varying amounts of citric acid. 

The ratings measured two things: how intense (in terms of sourness) a participant found a sample, and how much they liked its taste. Based on these responses, they divided the participants into three categories.

“A strong negative group where liking dropped with increased sourness, an intermediate group who showed a more muted drop in liking with more sourness, and a strong positive group where liking increased with more sourness,” the study authors note. 

The most surprising outcome of this study was that the cohorts in Italy and the US had a similar percentage. Both cohorts showed 11-12% preference for sourness, despite having so much difference in their food habits and lifestyle. This finding suggests that there could be a significant population across the globe that like sour flavours.

“Italian food culture and American food culture are so wildly different and yet we end up with almost identical percentages, which suggests to us this is not an effect of prior exposure. It’s probably something innately different about those people. We don’t know what that is, but it tells us that it’s not just the foods you grew up with,” Sara Spinelli, first author of the study and a sensory science researcher from the University of Florence, said.

Busting sour myths

A popular hypothesis suggests that “sour likers” can tolerate extreme tartness because their taste buds are less sensitive to this particular taste. So, these people experience less tartness compared to others even when consuming the same piece of lemon.

“But that’s not what we find. We find the people that like really sour flavor actually experience it just as sour as other people. They simply enjoy it more.” said John Hayes, one of the study authors and a professor of food science at the Pennsylvania State University.

Sourness also receives less attention from food and beverage companies. You might not have noticed, but this is probably why most edible packaged products are sweet, spicy, or salty. However, the study proves that there is a significant number of consumers for sour items as well.  

Moreover, according to the researchers, it is the balance between sourness and sweetness in many fruits, vegetables, and other food items that plays a key role in deciding whether people will like them. 

“This study highlights the importance of looking at individual differences and potential consumer segments, rather than merely averaging responses across all individuals within a group, because when we average the response, all we see is a dislike of sourness, we lose this subset of people who actually love it,” Spinelli said.

it is important to note, however, that the citric acid experiment was conducted on a limited number of participants. Therefore, further research involving a much higher number of subjects is required to validate these findings.

The study is published in the journal Food Quality and Preference.