Summary: Researchers have discovered that “sourness” is far more complex than a single taste sensation on the tongue. By comparing five common organic acids—citric, malic, lactic, fumaric, and tartaric—a new study reveals that different acids produce vastly different levels of sourness, puckering, and mouth-drying sensations, even at identical concentrations.
While citric acid (citrus) was found to be the most intense, lactic acid (fermented foods) was the mildest. The study also debunked the idea that a love for sour foods is tied to “risk-taking” personalities, suggesting instead that a preference for tartness is likely shaped by dietary exposure rather than character traits.
Key Facts
- Not All Acids Are Equal: Citric acid produces the strongest puckering and sourness, while lactic acid produces the least, even when used in the same amounts.
- Three Consumer Profiles: People generally fall into three categories: those who immediately dislike sourness, those who gradually dislike it, and the “sour seekers” (roughly 1 in 8 adults) who enjoy the sensation more as it intensifies.
- Mouthfeel Matters: Sourness isn’t just a taste; it is intrinsically linked to physical sensations like puckering (astringency) and drying of the mouth.
- Diet vs. Personality: Unlike spicy or bitter food preferences, which are linked to sensation-seeking personalities, sour preference appears to be driven by habitual dietary exposure.
Source: Penn State
Biting into a tart green apple is a different taste and sensory experience than sucking juice from a lemon, and both significantly vary from accidentally consuming spoiled milk.
Each of these foods contains a different organic acid that gives rise to the flavor commonly referred to as “sour,” even when the taste and related mouthfeel sensations such as puckering and drying vary drastically from food to food and person to person.
Now, Penn State researchers have found that while some of that difference comes from individual perceptions, the acids themselves vary in sourness, even at the same concentrations.
The researchers, who recently published their findings online in advance of the March issue of Food Quality and Preference, explained the work builds on their 2024 study that revealed roughly one in eight adults like intensely sour sensations and exceptionally sour foods.
This new study dives deeper into why different acids taste differently sour, why people disagree on how sour things taste, and why some people love sour foods while others really don’t.
“Beyond just being interesting, these findings might help guide the food industry in making formulations for sour foods because these different acids have subtle taste and mouthfeel nuances to them,” said study senior author Helene Hopfer, associate professor of food science in the College of Agricultural Sciences.
“We found that sourness isn’t experienced as just taste — it’s also puckering and it’s also drying. Equal amounts of different acids do not create equal sourness or mouthfeel. People vary widely in both how much sourness they like and how strongly they perceive it.”
The researchers recruited 71 everyday consumers — not trained tasters — who eat or drink sour foods at least once a month.
The participants tasted water solutions containing equal amounts of five acids: lactic — found in sauerkraut, pickles and milk; malic — found in Granny Smith apples, fumaric — found in papayas, pears and plums; tartaric — found abundantly in grapes; and citric — in citrus fruits and juice.
Each acid was tested at four increasing concentrations. Participants rated sourness, puckering, drying and overall liking.
“Because all these different organic acids are widely used by the food industry, and they’re food safe, there’s a lot of conventional wisdom, ‘well, you use this one for this application or use that one for that application,’” said study coauthor John Hayes, professor of food science.
“But we really wanted to unpack all of that and do a systematic apples-to-apples comparison.”
The results suggest that different acids do not taste equally sour, even at the same concentration. Overall, citric acid produced the strongest sourness and puckering overall. Lactic acid produced the least sourness and puckering.
More specifically, the participants generally fell into one of three groups: those who more immediately disliked the taste as sourness increased; those who more gradually disliked the taste as sourness increased; and those who liked the food experience more as the sourness increased.
The groups didn’t just taste and like sourness differently — they experienced it differently, Hayes noted. The group that more sharply disliked the taste rated sourness, puckering and drying as more intense, especially at high concentrations. This effect was strongest for non-citric acids. The opposite group that liked the sourness reported consuming more citrus fruit juices and tart fruits.
“Equal amounts of different acids do not create equal sourness or mouthfeel,” Hayes said.
“People vary widely in both how much sourness they like and how strongly they perceive it. These differences matter most for acids other than citric acid and could be important for food formulation, product optimization and tailoring sour foods to different consumer segments.”
Using validated surveys, Hayes and colleagues previously found that those who like spicy food tend to have specific personality characteristics, like being motivated by rewards and an inclination toward taking risks.
They also previously found that those who like and seek out bitter tastes, like pale ales, are also more prone to taking risks.
“However, in this study, the participants who prefer sour taste did not demonstrate different personality traits from the other groups, so sour preference seems linked to dietary exposure, not personality,” Hayes said.
“We looked at whether or not personality traits were related to strong liking of sour taste because we’ve done a lot of work showing that people who like the burning sensation from chili peppers are risk takers and adventure seekers,” he said.
“We wondered whether people who were a little more sensation seeking or risk taking and adventurous might strongly like sour taste. We thought that might explain why those one in eight adults really likes intensely sour sensations. But that didn’t work out— there was no relationship.”
Study first author Astrid D’Andrea recently earned her master’s degree in food science from Penn State.
Funding: The U.S. Department of Agriculture’s National Institute of Food and Agriculture funded this research.
Key Questions Answered:
A: It comes down to perception and exposure. The study found that “sour seekers” actually perceive the intensity of puckering and drying as less extreme than those who dislike sour foods. This group also tends to eat more tart fruits and juices regularly.
A: It’s both. Researchers found that sourness is a multi-sensory experience that includes “puckering” and “drying.” Different acids trigger these physical mouthfeels in different ways, which is why a tart apple feels different than spoiled milk.
A: Probably not. While people who love spicy chili peppers often have adventurous, risk-taking personalities, this study found no such link for sour lovers. Your craving for tartness is likely just a result of what you grew up eating.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this taste perception and neuroscience research news
Author: Adrienne Berard
Source: Penn State
Contact: Adrienne Berard – Penn State
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Consumer segmentation for sourness: exploring perception, liking, personality, and intake” by Astrid D’Andrea, John Hayes, and Helene Hopfer. Food Quality and Preference
DOI:10.1016/j.foodqual.2025.105811
Abstract
Consumer segmentation for sourness: exploring perception, liking, personality, and intake
Organic acids are commonly added for sourness in food, but published data on relative sourness at equimolar concentrations is lacking, and related attributes like puckering and drying remain understudied.
Here, we compare different organic acids in a large sample of naïve consumers. Participants (n = 71) who reported consuming sour foods or beverages at least once a month rated attribute intensities and overall liking of aqueous equimolar solutions of lactic, malic, fumaric, tartaric, and citric acid across four log concentrations.
Dose-response functions revealed acid-specific intensity differences. Citric acid induced the most sourness and puckering, while lactic acid induced the least.
Based on the linear mixed effects model coefficients, relative to lactic acid, sourness increased the most with fumaric and malic acid, followed by tartaric, and citric acid.
Based on affective data and recent literature, participants were segmented into three hedonic groups: (1) a Strong Negative (SN) group showing a strong drop in liking with increasing concentration, (2) an intermediate Weak Positive-Negative (WP/N) group where liking dropped more gradually, and (3) a Strong Positive (SP) group where liking increased with increasing acid concentration.
Notably, the three groups differed in their perception of sourness, puckering, and drying, which was more pronounced for the non-citric acids tested. Strong sour dislikers (SN) rated these attributes as more intense than the other groups, particularly at higher concentrations.
Compared to the SN group, strong sour likers (SP) self-reported a significantly higher intake of citrus/tart fruits and fruit juices, but no personality differences were observed.
