The effect of milk on the amount of antioxidants in black tea

1. The effect of milk on the amount of antioxidants in black tea Group Number: 1-032 Sim Nigel (leader)-2O2(26) Chen Xingjian-2A4(03) Ethan Ong-2O2(25) Chong Zhi Lin-2A4(06)

2. Contents • Introduction • Objectives • Hypothesis • Variables • Materials • Methodology • Result • Conclusion • Reference

3. Antioxidants in tea • Antioxidants are chemicals released in tea. • These chemicals help reduce aging. • They also lower the risk of getting cancer. • Slows down the oxidation of other molecules. • Some of the more well known antioxidants include beta carotene, lycopene, selenium, glutathione, lipoic acid, coenzyme Q10, vitamins A, C and E, and other substances.

4. General Facts • Black tea is also known as red tea. • Black tea is commonly found in hawker centres in Singapore.

5. Objective and Hypothesis • Objective of the study: • To study the effects of milk have on the amount of antioxidants in black tea. • Hypothesis: • The longer the black tea is exposed to air, the lesser the amount of antioxidants. • The antioxidant level in black tea with milk will be higher than that in black tea without milk.

6. Dependent Variable • The amount of antioxidants reduced.

7. Independent Variable • Milk • 5 ml • None • Recording Times • Immediately after tea preparation • 15 min after tea preparation • 30 min after tea preparation • 45 min 30 min after tea preparation • 1 hour after tea preparation • 1 hour 15 min after tea preparation • 1 hours 30min after tea preparation • 2 hours after tea preparation

8. Controlled Variables • Number of tea bags used • Amount of water added • Amount of milk added • Volume of tea for measurement of antioxidant level • Water temperature when making the tea • Room temperature

9. Materials • Beakers • Condensed milk (Carnation milk) • Black Tea – Tea Bags (brand: Lipton) • Boiled tap water. • ABTS (2,2'-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid) • UV spectrometer

10. Study Design • The following 2 groups will be studied: • Control group: no milk added • Study group 2: 5 ml milk added • Time points to measure antioxidant level: • Immediately after tea preparation • 15 min after tea preparation • 30 min after tea preparation • 1 hour after tea preparation • 1 hour 15 min after tea preparation • 1 hour 30 min after tea preparation • 2 hours after tea preparation

11. Procedures • Set-up • Control • Add 15ml of water. • Milk • Add 5 g of milk into a beaker and add boiled water until it reaches the 15ml mark. Stir well. Note*( Using magnetic stirrer to stir)

12. Flowchart of procedures

13. Procedures • Preparation of tea • Boil 500ml of water • Add three bags of black tea into the water and wait for 5 mins, stir well. • Take out the tea bags. • Pour 200ml of tea into each of the two beakers prepared earlier. Mix well. • Check that the total volume of tea in each beaker is 215ml.

14. Procedures • Time points to be measured the amount of antioxidants • Immediately after tea preparation (baseline) • 15 min after tea preparation • 30 min after tea preparation • 1 hour after tea preparation • 1 hour 15 min after tea preparation • 1 hour 30 min after tea preparation • 2 hours after tea preparation

15. Procedures • Antioxidant measure: • Place 3ml of ABTS into a small test-tube. • Drop 20μl of the tea sample into the small test-tube. • Shake well. • Then, place it into the UV spectrometer. • The readings will then be shown. • Below is how we will calculate the amount of antioxidants in the tea sample: • ( X is the reading shown on the UV spectrometer) • Three readings of each group will be taken and the median will be used for the data analysis.

16. Analysis Methodology • Three repetitions will be done for each setup. • Repeat measurement technique (mixed model) will be utilized to evaluate the effects of milk on slowing down the loss of antioxidant. • Mean reduction of antioxidant level at each time point from baseline will be compared by paired T test.

17. Result • Anti-Oxidant Level at each time point

18. Result • Reduction of Anti-Oxidant Level

19. Result • Mean Reduction of Anti-Oxidant Level P=0.085 Mean difference: 4.02 (95% CI -0.70 – 8.75)

20. Conclusion • Adding milk to black tea slows down the loss of anti-oxidants. • Further study: • Larger sample size to confirm our finding. • Milk effect on other forms of black tea such as tea leaf instead of tea bag. • Milk effect on other types of tea such as green tea, WuLong Tea.

21. Reference • “Influence of milk and sugar on antioxidant potential of black tea” • VasundharaSharma,H. Vijay Kumar, L. Jagan Mohan Rao • Food Research International, Vol.41, Issue 2, 2008, 124 – 9 • http://www.news-medical.net/health/What-are-Antioxidants.aspx • http://www.webmd.com/food-recipes/features/antioxidants-in-green-and-black-tea • http://www.ncbi.nlm.nih.gov/pubmed/16020939 • http://www.livestrong.com/article/536591-does-tea-with-milk-take-away-antioxidants/ • http://www.nutraingredients.com/Research/Milk-s-fat-content-may-influence-tea-s-antioxidants

22. The end Thanks for listening. 