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

Contents  Introduction  Objectives  Hypothesis  Variables  Materials  Methodology  Result  Conclusion  Reference

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.

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

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.

Dependent Variable  The amount of antioxidants reduced.

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

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

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

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

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)

Flowchart of procedures Preparation of tea Time points to be measured Analysis Methodology

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.

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

Procedures

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.

Result  Anti-Oxidant Level at each time point

Result  Reduction of Anti-Oxidant Level

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

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.

Reference  “Influence of milk and sugar on antioxidant potential of black tea”  Vasundhara Sharma, H. Vijay Kumar, L. Jagan Mohan Rao  Food Research International, Vol.41, Issue 2, 2008, 124 – 9  Antioxidants.aspx Antioxidants.aspx  recipes/features/antioxidants-in-green-and-black-tea recipes/features/antioxidants-in-green-and-black-tea   milk-take-away-antioxidants/ milk-take-away-antioxidants/  content-may-influence-tea-s-antioxidants content-may-influence-tea-s-antioxidants

The end Thanks for listening.