How does the colour of a drink influence taste? By Cindy Purvis and Louise Godhard- Yr 8 SCEGGS Darlinghurst, NSW Australian Statistics Competition AMT 2015

Introduction Our eyes have been conditioned to see certain foods in a particular way and while some colours stimulate taste buds, others are capable of killing the appetite. Experts have long known that colour plays a crucial role in the taste and perception of food. Alongside flavour and texture, colour is considered by food scientists to be a major quality factor of food. In fact, it might be the most important of the 3. “If you don’t have the colour right, I think you can forget about the other two,” says Jack Francis, food scientist at the Univ. of Massachusetts. “If it isn’t the colour you expect it to be, you don’t like it. We would like to test this theory ourselves.

Aim and Hypothesis Aim: To investigate whether the colour of food/drinks affects a person’s sense of taste. Hypothesis: That a red-coloured drink will appeal to the persons’ tastebuds more than any of the others. A green-coloured drink will appeal least to the persons’ tastebuds in comparison to the others.

Equipment / Ingredients 3L of Fruit Juice containing: Pineapple, Mango, Passionfruit, Guava, Apple and Grape 60 plastic cups Red odourless food dye Yellow odourless food dye Green odourless food dye Purple odourless food dye

Method 1.Pour 50mL of the juice into 15 cups. 2.Colour each cup of juice with 2 drops of odourless red food dye and stir until mixed well. 3.Give the juice to 15 test subjects. 4.Repeat steps 1-3 (on separate days) Using a different odourless food dye each time. (Green, Yellow, Purple) 5.Get them to rank each juice in order of favourite to least favourite. (More information on the next page.) 6.Record the rankings from each person and average results (each juice must be given a different ranking)

How to measure rankings Each student must rank their juice from favourite to least favourite. When calculating the results, the juice that is ranked 1st by the person will get 4 points and the juice ranked 4th will get 1 point. Example: 1.Red Smoothie = + 4 points 2.Green Smoothie= + 3 points 3.Yellow Smoothie= + 2 points 4.Purple Smoothie= + 1 points

Results Table PersonRed JuiceGreen JuiceYellow JuicePurple Juice Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject Subject

Results Points Juice ColourNo. of Points Red Juice45 Green Juice43 Yellow Juice20 Purple Juice42 Based on these results:  30% of the points went to the red juice  28 2/3% of the points went to the green juice  13 1/3% of the points went to the yellow juice  28% of the points went to the purple juice

Results Graph

Statistics Here are some statistics that we discovered from our experiment based on our results: 40% of students like the red juice the best 26 1/3 % of students like the green juice the best 0% of students liked the yellow juice the best whilst 80% liked this juice the least 33 1/3 % of students liked the purple juice the best 6 2/3 % of students voted for the order 1. red, 2. green, 3. yellow, 4.purple 6 2/3 % of students voted for the order 1. purple, 2. red, 3. green, 4. yellow

Statistics Continued 6 2/3 % of students voted for the order 1.green, 2.purple, 3.red, 4.yellow 6 2/3 % of students voted for the order 1.purple, 2.yellow, 3.green, 4.red 13 2/3 % of students voted for the order 1.red, 2.purple, 3.green, 4.yellow 13 2/3 % of students voted for the order 1.purple, 2.green, 3.red, 4.yellow 20% of students voted for the order 1.red, 2.green, 3.purple, 4.yellow 26 2/3 % of students voted for the order 1.green, 2.red, 3.purple, 4.yellow

After we completed the first part of our experiment, we decided to test what students actually tasted these juices as. We asked students to guess what the main fruit in each juice was, and we had some astonishing results.  Red Juice: 80% of students thought it contained pomegranate, 13 2/3 % of students thought it contained blood orange and 6 1/3 % of students thought it contained guava.  Green Juice: 66 2/3 % of students were not sure what it contained, 20% of students thought it contained celery and 13 1/3 % of students thought it contained guava.  Yellow Juice: 60% of students thought it contained passion-fruit, 26 2/3 % of students thought it contained mango, 6 2/3 % of students thought it contained lemon and 6 2/3 % of students were not sure.  Purple Juice: 80% of students thought it contained Cranberry, 20% of students weren’t sure. More Experimenting

Analysis Traditionally, scientists thought that the tongue, nose, and brain dominated how people experience the flavours of the food. However, recent studies have revealed that taste is affected equally by how it is interpreted by the eyes, tongue, nose and brain. In our experiment, although we kept the smell and taste the same, we found that when we changed the colour, people responded differently to it. Students probably liked the red juice the best because it was easy to assume what was in them. Red juices usually contain strawberries, raspberries, etc. These fruits are well-liked. Even though the juice didn’t contain any of these fruits, people convinced themselves that these fruits were in them and found comfort in the fact that it appeared normal.

Analysis Continued The next most popular juice was the green juice. Green juices are a rising trend in society, because they have health benefits in the form of a juice. When we dyed the juices green, students may have thought it was a healthy concoction so responded positively. The purple juice was still fairly popular as people assumed there was cranberry and grape in it. Although they were obviously reluctant to drink a purple juice, the fact that they thought they could see the fruit it contained changed their perception. The yellow juice was least liked. This is because yellow is not a very appealing colour for something that a person is drinking. It was not clear what kind of fruits were in it, so people responded fairly negatively to it.

Although we did repeat our experiment on 15 students, we could have improved our experiment by repeating it again on another 15 students. This would ensure that our results were not biased or inaccurate. In order to create a more accurate result, we could have also tested students from a variety of year groups as well as adults. This would give us a broader idea of society at large. Also, we could have tested a wider range of colours for juices, as the ones we used were primary colours and fairly appealing. It would have been interesting to see results from brown and blue juices. To improve the reliability of our experiment, we could have also done the same experiment again using a different base juice. Discussion

Overall, we found that there is a relationship between the colour and perception of taste of juice. This does affect how a person perceives it, even to the point of making people think that there were different fruits in it. Students like red juice the most, green juice second, purple juice third and yellow juice least. The red, green and purple juices had very similar scores, but the yellow juice was clearly the least favourite. Conclusion