Summary: New research shows that “sourness” is not a single, uniform taste. By testing five common organic acids—citric, malic, lactic, fumaric, and tartaric—investigators found pronounced differences in perceived sourness, puckering, and mouth-drying, even when acids were presented at equal concentrations. The findings clarify why biting a green apple, sucking a lemon, and tasting spoiled milk feel so different on the tongue and in the mouth.
Citric acid (from citrus) produced the strongest sour and puckering sensations, while lactic acid (found in many fermented foods) was the mildest. The study also suggests that enjoyment of tart flavors is more strongly linked to dietary exposure than to personality traits such as risk-taking.
Key Facts
- Acids differ in effect: Equal concentrations of different organic acids do not evoke equal sourness or mouthfeel; citric acid ranks highest in sourness and puckering, lactic lowest.
- Three consumer segments: Participants clustered into three groups—those who dislike increasing sourness sharply, those who dislike it gradually, and “sour seekers” (about one in eight) who prefer stronger sour sensations.
- Mouthfeel is essential: Sourness includes taste plus tactile sensations like puckering (astringency) and mouth drying; these mouthfeels vary by acid.
- Diet shapes preference: Preference for sour taste correlates with habitual intake of tart fruits and juices rather than with sensation-seeking personality traits.
Source: Penn State
Biting into a tart green apple differs from sucking on lemon juice or accidentally tasting spoiled milk. Each experience is driven by different organic acids that create not only sour taste but distinct mouthfeel differences—puckering and drying—that make the sensations unique.
Penn State researchers published a detailed comparison of five organic acids in Food Quality and Preference. This work builds on a 2024 study that identified a subset of adults who seek intense sour experiences. The new study explains how acids differ in perceived intensity, why individuals disagree about sourness, and why some people enjoy sour foods more than others.
“These findings can guide the food industry when formulating sour products because each acid brings subtle taste and mouthfeel differences,” said Helene Hopfer, associate professor of food science and senior author. “Sourness is not purely taste—it includes puckering and drying. Equal quantities of different acids do not yield equal results, and people differ widely in both liking and perception.”
The study recruited 71 everyday consumers—not trained tasters—who reported consuming sour foods or beverages at least monthly. Participants tasted aqueous solutions containing equimolar concentrations of five acids: lactic (common in fermented foods and dairy), malic (apple), fumaric (found in papaya, pear, plum), tartaric (grape), and citric (citrus). Each acid was presented at four increasing concentrations and rated for sourness, puckering, drying, and overall liking.
Results showed clear acid-specific differences. Citric acid provoked the strongest sour and puckering sensations; lactic acid the weakest. Across participants, three hedonic groups emerged: Strong Negative (rapid drop in liking with increasing sourness), Weak Positive-Negative (gradual decline in liking), and Strong Positive (increased liking as sourness intensified). The Strong Negative group perceived sourness, puckering, and drying as more intense—especially for non-citric acids—while Strong Positive participants reported higher intake of citrus and other tart fruits and juices.
“People vary widely in both how much sourness they like and how strongly they perceive it,” said coauthor John Hayes, professor of food science. “These differences matter most for acids other than citric and are important for product design and targeting different consumer segments.”
Previous work by the team linked preferences for spicy and bitter foods to personality traits like sensation seeking and risk taking. In contrast, this study found no personality differences among sour preference groups, supporting the idea that dietary exposure—what people habitually eat—plays a larger role in shaping sour taste liking.
Study first author Astrid D’Andrea recently completed a master’s degree in food science at Penn State. Funding was provided by the U.S. Department of Agriculture’s National Institute of Food and Agriculture.
Key Questions Answered:
A: It’s a mix of perception and exposure. “Sour seekers” perceive puckering and mouth-drying as less intense and also tend to consume more tart fruits and citrus juices, which likely increases tolerance and enjoyment.
A: Both. Sourness combines taste with tactile mouthfeels such as puckering and drying. Different acids trigger these sensations to different degrees, so a tart apple, lemon, and spoiled milk all feel distinct.
A: Unlikely. Unlike preferences for spicy or bitter sensations, which have been associated with adventurous personality traits, sour preference in this study was not linked to personality and appears to be shaped mainly by diet.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by 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 used to create sourness in foods, yet comparative data on their relative sensory impact at equal concentrations are limited, and related mouthfeel attributes like puckering and drying are often understudied. In this study, 71 naïve consumers who regularly consume sour foods rated equimolar aqueous solutions of lactic, malic, fumaric, tartaric, and citric acid at four concentrations for sourness, puckering, drying, and overall liking. Dose–response analysis revealed acid-specific differences: citric acid produced the strongest sourness and puckering, while lactic acid produced the weakest. Based on hedonic responses, participants segmented into three groups: Strong Negative (liking falls sharply with increasing concentration), Weak Positive–Negative (liking decreases gradually), and Strong Positive (liking increases with concentration). These groups also differed in perception of sourness, puckering, and drying—differences that were more pronounced for non-citric acids. Strong sour likers reported higher intake of citrus and tart fruits, while personality measures did not differ across groups, indicating dietary exposure rather than personality drives sour preference.