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.
Top Related