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

ProceduresSet-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

AnalysisMethodology

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 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.

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=0.085Mean difference:4.02 (95% CI -0.70 – 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 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-wi

th-milk-take-away-antioxidants/

http://www.nutraingredients.com/Research/Milk-s-fat-content-may-influence-tea-s-antioxidants

The endThanks for listening.