Bio project

1. Bio project Group leader: Sandy Hui Group member: Emily Yeung Heike Lam

2. Objective • To find out the amount of sugar different drinks contain qualitatively. • To investigate whether the sense of taste of human is reliable.

3. Introductionfor the project • As our goal of this project is to find out whether the taste of human is truly reliable, the interviewees were asked to taste 8 different drinks which includes tastes like bitter, sour and sweetness. • Then the interviewees are asked to arrange the degree of sweetness. • The sweetest the drink is, the highest degree is the result collected and it is checked with the Benedict’s test we had carried out, which was tried to test the amount of sugar qualitatively.

4. Introduction for Benedict's test • Reducing and non-reducing sugar present in the 8 different drinks are tested using Benedict’s test qualitatively. • Acid are used to hydrolyze the non-reducing sugar and then boiling is needed. Precipitate will form as sugar is present. • Filter the precipitate and measure the weight of the precipitate.

5. Introduction of tasting • Interviewees were asked to taste the 8 different drinks. • Grades according to sweetness were given by the interviewees. • After each trial of one drink, interviewees were required to drink water to wash away the sweetness of the previous drink.

6. predictions • For Benedict's test • Brick red precipitate will be formed when reducing and non-reducing sugar is present. • The result is concordant with the nutritional claim. • For tasting test • It is predicted that the sense of taste of human is not reliable that they may be deceived by the taste of bitter or sour---they may have the misconception that drinks with bitter or sour tastes contains less amount of sugar.

7. Assumptions

8. Variables

9. Apparatus/Materials

10. Procedure for Benedict’s test • Set up a water bath and boil it for later use. • Put the filter papers into oven to dry them up for 10 minutes • Add 1ml of the samples into different test tubes. Then add 5 drops of 0.1M HCL. • Mix them well and boil the mixture in the water bath for 5 minutes. • Add 5 drops of 0.1M NaOH into each test tube to neutralization. • Add 5ml Benedict’s solution and boil the mixture again for 5 minutes. • Take the filter papers out and measure their weight. • Carefully filter the precipitate with the weighted filter papers. • Wash all the precipitate of the test tubes into the filter papers. Be careful not to add too much water or else the paper will be damaged with holes. • Put the filter papers into 100℃ oven for 1 day. • Take out the filter papers after 1day and measure the weight of the papers again.

11. Procedure for tasting test • rinse the mouth with water thoroughly. • Taste 8 different drinks in order. • After each trial of 1 drink, repeat step 1. • Record the grades of sweetness given by the interviewees. • Ask the interviewees to distinguish which drink is lite.

12. Label all the test tubes to prevent any mixing up of the drinks. Wash the pipette before use to avoid contamination. Ensure the drinks contain no residue or else the precipitate present may not all are due to the sugar present in the drink. tasting PRECAUTIONS

13. Resultof Benedict’s Test

14. Table showing the result of Benedict’s test

15. Table showing the result of Benedict’s test (continued)

16. Calculation • Average weight of precipitate of the two trials ={ [the whole system’s final weight ( precipitate + filter paper) – filter paper’s weight ] in trial one + [the whole system’s final weight ( precipitate + filter paper) - filter paper’s weight ] in trial two} / 2 • The molar mass of glucose ( C6H12O6) =12x6+1x12+16x6 =180 gmol^-1 • Mass of sugar present in 100ml 1M glucose solution = 18g • Mass of sugar present in each 100ml drink 18x (mass of precipitate in drink samples/ mass of precipitate in glucose solution)

17. Discussion about the Benedicts’ test

18. Discussion • Interpretation of the result • According to the mass of sugar in each 100ml drink, we can get the trend of sweatiness of drinks the trend is as below: I>E>G>D>C>H>B>A>F>J • The higher the amount of red precipitate the drink has, the higher the mass of sugar in each 100ml drink • 1M glucose solution has the highest amount of sugar in 100ml of it • Water as a control has the lowest amount of sugar in 100ml of it • Among drinks, 100ml yakult has the highest sugar content while hung fook tong american ginzen with honey drink has the lowest sugar content

19. Table comparing the sugar content in 100ml of each drink in the experiment result and the nutrition label

20. Picture showing the result of the experiment ( precipitate on filter paper)

21. Picture showing the result of the experiment ( precipitate on filter paper)

22. Comparison between the nutritional label and the experiment result • The trend of the amount of sugar content in each 100ml drink in nutritional label I>E>D>C>G>H>B>F,A>F • The trend of the amount of sugar content in each 100ml drink in experiment result I>E>G>D>C>H>B>A>F>J • Generally speaking, both trends are quite similar only with three of them ( D,C,G) in the wrong order. • The wrong order may because of the errors in carrying out the experiment

23. Error • The sugar content done by the experiment and that in nutritional label is more or less the same • The relative error between the experiment result and the nutritional label can be minimized by using more amount of drinks to carry out the test ( e.g. 200ml) • There are some result cannot be done in the experiment because of the failure of filtration of precipitate • Some filter paper may be holed by the precipitate and thus we cannot get the result of the amount of precipitate, hence the amount of sugar ( * in table indicated the unknown data)

24. control • In this experiment, control is set up by replacing the drinks with distilled water. • Having a control can know whether the result have affected by some environmental factors like temperature. • To show any precipitate formed is due to sugar presented in drinks • In this experiment, another control is set up replacing the drinks with 1M glucose solution in order to carry out a quantitative test • Through doing quantitative test, we can calculate the amount of sugar content in each drink

25. Result of the tasting test

26. Graph showing the sweetness tasted by different testers *★ is an arbitrary value(7★= very sweet, 1★= slightly sweet, - =not sweet at all) **☆ = 1/2 ★ ***@means that tester can state that drink is a ‘less sweet’ formula

27. Results of Taste test • The sweetness tasted by testers in descending order E>D>G>A>B>F>C>H • The sugar content claimed by nutrition label E>D>C>G>H>B>F,A • By comparing two sets of data, taste of testers are not totally reliable. • However, we can see that the experimental trend roughly echo with the claimed one: E>D>G>B>F The above trend can be found in both data

28. Discussion about the tasting test

29. Discussion – Is human taste is reliable? The reliability is so-so. In what way it’s reliable: 1.Most of data of the trend we get echoes with the official one (E>D>G>B>F) 2.Although the sweetness of Yakult only worth 6stars, 2/3 of the testers agree that Yakult is ‘7 stars sweet’, which is ‘very sweet’ !. Indeed, it contains 9.1g of sugar per 100ml, which is very sweet in reality. . Graph showing the tasted sweetness and the actual amount of sugar of drinks

30. Discussion – Is human taste is reliable? • in what way human taste is unreliable? • Comparing coffee and milk tea, the former contains more sugar than the latter but the former taste less sweet than the latter • Comparing milk tea and ginzen drink, they contains same amount of sugar. However, milk tea tastes sweeter than Ginseng drink Graph showing the tasted sweetness and the actual amount of sugar of drinks

31. Discussion – Is human taste is reliable? in what way human taste is unreliable? 3. Lucozade contains 9.1g of sugar(which is 3rd highest amount of sugar) but it only tastes like the 2nd least degree in sweetness 4. Slimilk contains 7.1 g of sugar but surprisingly, almost no one can find out the sweet taste. Graph showing the tasted sweetness and the actual amount of sugar of drinks

32. Discussion – Is human taste is reliable? in what way human taste is unreliable? 5.Out of 11 testers, only 2 and 1 can point out the lemon tea or Ribena they are drinking is a ‘less sweet’ formula respectively. Graph showing the degree of sweetness of 2 drinks tasted by testers

33. Discussion – Our interpretation Let’s go back to the comparisons with milk tea. Both coffee and ginseng drink contains a natural bitter taste. Our sense of taste is kind of ‘faked’ by the bitter Taste. When comparison is made between bitter drinks and milk tea (which is not bitter), those bitter ones tastes less sweet than it supposed to be. Graph showing the tasted sweetness and the actual amount of sugar of drinks

34. Discussion – our interpretation Here comes the Lucozade example. Lucozade contains citric acid and lactic acid. Taste buds responds to H+ groups of acid and get the sense of sourness. Human tongue is ‘faked’ by the sour taste again so lucozade taste less sweet than it should be. Graph showing the tasted sweetness and the actual amount of sugar of drinks

35. Discussion – our interpretation Slimilk contains 7.1g of sugar but it tastes unsweetened at all! The reason is, those 7.1g sugar is lactose indeed. Lactose is a disaccharide making up 2-8% of milk which only possesses a subtle sweet taste. So only those supertaster (very sensitive ones) can sense the sweetness of lactose Graph showing the tasted sweetness and the actual amount of sugar of drinks

36. Research – why human taste is unreliable • Let’s be clear about the following terms: Flavor and Taste. • Taste is the signal received by taste bud in respond to chemical in the food. It will be transmitted to the brain • Flavor is the overall impression of how the food ‘tastes like’, affected by smell, sight and many other factors.

37. Research – why human taste is unreliable • Approximately 80-90% of what we perceive as "taste" actually is due to the sense of smell. • With out smell, we can only taste 5 basic tastes: bitterness, saltiness, sourness, sweetness and Savoriness, which is the taste produced by amino acids such as glutamate

38. Research – why human taste is unreliable • The brain interprets signals from taste, smell and even vision before turning them into an impression of the food's taste, known as flavor. • These senses play an important role in precepting flavor: • Sight: an unsweeten soda water with artificial orange color added might tastes like an genuine orange soda • Pain: the spicy and hot taste of chili is actually a sense of pain

39. Research – why human taste is unreliable • Chewing helps to transfer odour from the mouth to the back of the nose. • The area which is sensitive to smell is located at the back of the nose where several million receptor cells per square centimetre respond to thousands of chemicals in the food.

40. Research – why human taste is unreliable • To conclude, the flavor we percept is affected by a bunch of factors including pain, smell, action of chewing,etc. • As our testers are in normal health status, their sense of smell is valid. So that the sweetness of drink they taste is affected by their own smell. • Also, other component of taste like bitterness in ginseng drink also affect the perception of sweetness.

41. conclusion • yakult contains the most amount of sugar, following is vita lemontea(less sweet), lucozade(original),ribena(less sweet), Kowloon dairy hi-calcium slim milk, Nescafe(rich),nestle milk tea and hung fook tong American ginzen with honey drink, in which nestle milk tea and hung fook tong American ginzen with honey drink contains the same amount of sugar.

42. Conclusion(2) • Respondents find yakult(E) contains the most amount of sugar, followed by lemon tea(D), and milk tea(A) and ribena (G)(same value for milk tea and ribena). Next comes coffee(B) and gizen drink(F). Then is lucozade(C). People find slim milk(H) contains no sugar at all. Key: 7- least sweet,1- most sweet

43. application1 • As one cannot notice any difference between the ‘less sweet’ formula and the ‘original flavor’ flavor of drink, ‘less sweet’ drinks are suggested to buy. • Sugars may be added to foods to make them more palatable and are found in calorie-rich foods, which may lead to a higher calorie diet, excess weight and cavities. • This is why most nutrition experts recommend limiting added sugars (excluding fruit and milk) to 40 grams per day or 10 teaspoons (4 grams is in one teaspoon). • Total sugar content is easily identifiable on the Nutrition claim on the back of processed foods.

44. application2 • High intake of added sugars is implicated in numerous poor health conditions, including obesity, high blood pressure and other risk factors for heart disease and now it may lead to prematureaging. • sugar molecules have been shown to damage collagen. Since we naturally lose collagen as we age, the logical idea is to do whatever we can to prevent damaging it faster than needs be to prevent premature aging. • sugar contribute to deplete collagen levels in our body, • that depletion leaves your skin more vulnerable to sun damage. • So if you eat a lot of sugar, chances are that the molecules will stick to your collagen fibers and bind them together, hence creating dangerous toxins that reduce your skin’s elasticity and flexibility which is associated with younger and healthier skin.

45. application3 • Sugar content should not be the only concern while choosing drinks. • Other ingredient, like carbohydrate, also contribute to the energy value • Please do concern the energy value on the nutrition label too

46. Application-4 • According to our tasting test, although the sense of human is not totally reliable, it still roughly cohere with the true sweetness • we can rely on our own sense to determine the drink with least sugar in a restaurant (as nutrition label is never provided in a restaurant)