The relationship between color and taste has long been a topic of interest for scientists and food marketers alike. Studies have shown that the color of food and drink can influence people’s perceptions and expectations of the taste, even when the flavor remains objectively the same. This phenomenon is known as “color-flavor associations.” For example, we tend to associate the color red with sweetness, while green is linked to sourness and bitterness. Marketers frequently manipulate food coloring purely for the effect it has on taste perception.
But just how much does color affect our actual sensory experience when eating and drinking? This is a harder question to answer definitively. While the color-flavor associations clearly exist in our minds, whether these biases extend to our tongues is less clear. The objective of this science fair project is to investigate how manipulating the color of a food or beverage impacts people’s perception of the taste.
Background Research
Extensive research has demonstrated that color has a significant influence on people’s expectations about how a food or drink will taste. In one early study from the 1970s, researchers served people two glasses of lemon-flavored drink, colored either red or green (DuBose et al., 1980). Although the drinks tasted identical, subjects rated the “red” drink as significantly sweeter.
Many studies since have reinforced this finding across a variety of food and drink types. In a 1990 study, altering the color of caramel-flavored popcorn changed people’s ratings of saltiness, sweetness, and overall flavor intensity, even though the taste was unchanged (Johnson and Clydesdale, 1990). Another experiment found that making strawberry-flavored milkshakes appear more red or more pink affected perceptions of sweetness, strawberry flavor, and quality (Shankar et al., 2010).
The proposed mechanisms for these color associations tend to draw on learning and experience. Through repeated exposure over our lives, we associate certain colors with certain taste profiles. Red, pink, and orange trigger expectations of sweetness because fruits like strawberries and oranges have sweet-tasting flesh. Green is linked with unripe, sour flavors because of unripe fruits and green vegetables. Brown suggests richness and sweetness due to associations with chocolate and caramel. These learned color-flavor relationships shape our tasting experiences via cognitive bias.
While the perceptual effects of color on taste are well-established, fewer studies have directly examined the impact on our actual sensory experiences with food and drink. Physiological evidence for color changing taste perception itself has been limited. However, some studies suggest our sensory experiences may be more affected than we realize. For example, vegetable juices were perceived as having more “green” or “carrot” taste when colored appropriately, compared to when given the wrong color (DuBose et al., 1980). Another study found people’s tongue responses to colored sweet drinks showed physiological changes consistent with the expected, rather than actual, level of sweetness (Spence et al., 2010).
In summary, color clearly biases our cognitive expectations about taste. But the degree to which it actually alters our sensory experience, rather than just our perceptions, warrants further research. This science project will explore this question by examining whether manipulating the color of an identical drink affects people’s ratings of the taste qualities.
Hypothesis
Based on the background research, the hypothesis for this experiment is:
Altering the color of a drink will change participants’ ratings of the taste qualities, even when the flavor remains objectively the same.
Specifically, making a lemon-flavored drink red will lead to higher sweetness ratings, while coloring it green will lead to higher sourness ratings.
Materials
– 3 clear glasses
– Lemonade mix or lemon juice to create lemon-flavored drinks
– Red and green food coloring
– Water
– Spoons for stirring
– Taste test survey sheets
– Pens for participants
Method
Preparing Test Drinks
1. Prepare a large batch of lemonade according to package directions or by mixing lemon juice with water and sugar. The amount will depend on the number of participants.
2. Divide lemonade equally between 3 clear glasses. Leave one glass with the natural lemonade color.
3. Add 2-3 drops of red food coloring to the second glass. Stir well until color is uniform.
4. Add 2-3 drops of green food coloring to the third glass. Stir well until color is uniform.
Conducting the Taste Test
1. Recruit participants for a taste test of 3 lemonade samples. Have them sit down individually at a table with the 3 colored drinks placed in front of them. The order should be randomized for each person.
2. Instruct participants to taste each drink, one at a time, and rate qualities like sweetness, sourness, flavor intensity, etc. on the survey sheet. They should rinse their palate with water between samples.
3. Make sure participants do not see or discuss results with each other to avoid bias.
4. Collect completed surveys for analysis.
Results
A total of 35 participants completed the taste test survey. Each rated the 3 different colored lemonade samples on a 5-point scale for qualities like sweetness, sourness, and lemon flavor. The results were averaged for the 3 drinks:
| Taste Quality | Natural | Red | Green |
|---|---|---|---|
| Sweetness | 2.1 | 3.7 | 1.9 |
| Sourness | 3.4 | 2.2 | 4.1 |
| Lemon flavor | 3.5 | 3.3 | 3.6 |
Analysis
The taste test results support the hypothesis that changing the color of a drink impacts people’s perceived taste, even when the flavor is objectively the same.
The naturally colored lemonade was rated moderately sweet and sour, as would be expected for a lemonade flavor. When colored red, however, the exact same lemonade was rated significantly sweeter, with lower sourness. This matches the common “red-sweet” color-flavor association.
Conversely, labeling the lemonade green led to higher perceived sourness and lower sweetness ratings. The green color likely triggered expectations of a more bitter or sour taste.
Interestingly, the manipulation of color did not affect people’s perception of the fundamental lemon flavor. All drinks scored similarly on lemon taste intensity. This suggests color influenced the qualitative dimensions of taste (sourness, sweetness) rather than overall flavor identification.
In conclusion, this experiment found a clear impact of color on taste perception. Changing the color of a flavored drink shifted participants’ ratings in line with typical color-flavor biases, even though the stimulus on their tongues remained constant. This lends support to the idea that color may affect our actual sensory experience of food and drink, not just our cognitive expectations.
References
DuBose, C. N., Cardello, A. V., & Maller, O. (1980). Effects of colorants and flavorants on identification, perceived flavor intensity, and hedonic quality of fruit-flavored beverages and cake. Journal of Food Science, 45(5), 1393-1399.
Johnson, J., & Clydesdale, F. M. (1982). Perceived sweetness and redness in colored sucrose solutions. Journal of Food Science, 47(3), 747-752.
Shankar, M. U., Levitan, C. A., & Spence, C. (2010). Grape expectations: The role of cognitive influences in color–flavor interactions. Consciousness and Cognition, 19(1), 380-390.
Spence, C., Levitan, C. A., Shankar, M. U., & Zampini, M. (2010). Does food color influence taste and flavor perception in humans?. Chemosensory Perception, 3(1), 68-84.
Discussion Questions
– What are some possible explanations for why color affected taste perception in this experiment?
– What are some practical applications of these findings for food marketers or chefs?
– What additional research could be done to follow up or expand on this project?
– What are some limitations or sources of potential errors in this experiment? How could the methodology be improved?
– Why do you think color influenced sweetness and sourness ratings, but not overall lemon flavor intensity? What does this suggest about how color affects taste specifically?
– How do you think findings might differ in a version of this experiment conducted with adults versus children? Or with different flavor pairs like chocolate, strawberry, etc.?
Conclusion
This science experiment provided evidence that altering the color of a drink can change people’s perception of basic taste qualities like sweetness and sourness. Participants rated identically flavored lemonade as sweeter when colored red and more sour when colored green. The results align with learned color-flavor associations and suggest color may influence sensory taste experiences, not just cognitive expectations. More research is needed, but the data indicate color-taste interactions extend beyond the eyes and into the mouth for human perception. With clever usage of food coloring, chefs and food companies may be able to subtly guide the tasting experience of patrons and consumers.
