Transcript The Truth About the Tea - NDsciencefair

The Truth About Tea
The Antibacterial Effects of Green Tea:
Bottled vs. Brewed
Background Research (1)

Green tea has been shown to help with heart
disease, oral health, arthritis, weight loss, stress, flu,
food poisoning, colds, and other bacterial illnesses
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It can also help promote helpful bacteria in the
intestines
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Sweetened, flavored, bottled, and old green teas
have been shown to retain less antibacterial effects
as they are very processed
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Two types of bacteria were used: E. coli and strep
mutans
Background Research(2)–Bacteria

Escherichia coli (E. coli)
◦ Gram negative
◦ Bacteria found in intestines of warm blooded animals and
people
◦ Causes food poisoning and can be from consuming
undercooked or raw meat and vegetables, water, or
anything that comes in contact with animal manure
◦ Can cause diarrhea and eventually HUS/kidney failure
◦ Most documented outbreak of O157:H7
◦ Similar to Salmonella
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Streptococcus mutans
◦ Gram positive
◦ Bacteria found in teeth and mouth area
◦ Creates acid which causes tooth decay, and also damages
gums and roots
◦ Feeds on refined carbohydrates in milk, sugar, fruit, etc.
Question
 Which type/brand of green tea
has the most antibacterial
effects?
Hypothesis
 The brewed green tea made from
Chinese tea leaves will have the
most antibacterial effects.
Materials (1)
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Twenty-four sterile
 Ruler (in centimeters)
paper disks
 Sterile tweezers
Six Petri dishes with
 Incubator
tryptic soy agar
 Sterile swabs
Six empty Petri dishes  Goggles
Streptococcus mutans  Lab coat
purchased from a
 Gloves
catalog
 Permanent marker
Escherichia coli
 Tape
purchased from a
catalog
Materials (2) – Green Teas
Brewed Chinese green tea
 Trader Joe’s unsweetened bottled green
tea
 AriZona sweetened honey ginseng
bottled green tea
 Just Tea unsweetened bottled green tea
 Gold Peak sweetened bottled green tea
 Sterile water

Procedure
1.
2.
3.
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5.
6.
Petri dishes with agar were labeled with three tests for
each type of bacteria, and type of tea on outside
Empty Petri dishes were each filled with one of the types of
tea and sterile water, and the sterile disks were put in to
soak
Freeze dried E. coli and strep mutans cultures were
hydrated using sterile technique, and the bacteria was
incubated for approx. 24 hours
Sterile swabs were used to spread E. coli over three Petri
dishes, and strep mutans over three Petri dishes
One disk soaked in each type of tea was placed into each of
the dishes
The Petri dishes were incubated at 37 °C for approx. 48
hours, then the zones of inhibition were observed for both
types of bacteria
Variables

Independent
◦ The types of green tea; the types of bacteria
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Dependent
◦ The size of the zones of inhibition

Control
◦ The sterile water tests

Constants
◦ The two different types of bacteria, the types
of green tea and water, the length of
incubation
Data (1)
E. coli Avgs. of the Zones
Diameters of Zones (in millimeters)
12.00
10.00
8.00
6.00
4.00
2.00
0.00
Trader Joe's
Brewed
AriZona
Gold Peak
Types of Green Tea
Just Tea
Sterile Water
Data (2)
Strep Mutans Avgs. of the Zones
Diameters of Zones (in millimeters)
18.00
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
Trader Joe's
Brewed
AriZona
Gold Peak
Types of Green Tea
Just Tea
Sterile Water
Data (3)
Comparison of Averages of Zones of Inhibition
Diameters of Zones (in millimeters)
18.00
16.00
14.00
12.00
E. coli avg.
10.00
8.00
Strep avg.
6.00
4.00
2.00
0.00
Trader Joe's
Brewed
AriZona
Gold Peak
Types of Green Tea
Just Tea
Sterile Water
Possible Sources of Error
For the E. coli test, the time between
when the brewed green tea was made
and when it was tested was larger than in
the strep mutans test
 In the strep mutans test, the zones of
inhibition were very faint and may have
been inaccurately measured for any of
the teas

Continuations
 What other bacteria are green tea
effective on?
 Does green tea really help other, nonbacterial illnesses? (ex: cancer, arthritis,
etc…)
 Do other green tea products besides the
actual tea have antibacterial effects? (ex:
lotions, body washes, food, etc…)
 Are other alternative medicines more
antibacterial than green tea?
Conclusion
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All teas except for AriZona had at least a small amount of
antibacterial effects
The two sweetened teas (AriZona and Gold Peak) appeared
to have the least health benefits, although the error bars
are large
The flavored, sweetened, more processed teas had less
effects
Because of the range of data for brewed green tea, it can’t
be said whether it had a greater effect than any others
except AriZona
The hypothesis was rejected – Trader Joe’s had the most
effects overall and was very consistent in the data
Unsweetened, unflavored bottled green tea or brewed
green tea from loose leaves are still the best choices
Works Cited
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About E. coli. (2011). Retrieved from Marler Clark LLP, PS website: http://www.about-ecoli.com/
All about antioxidants. (n.d.). Retrieved from AriZona Beverage Co. website:
http://www.drinkarizona.com/index_national.html#health_anti_ox
Baker, S. L. (2010, August 17). Scientists discover how polyphenols in green tea may protect health of diabetics.
Retrieved from Natural News Network website:
http://www.naturalnews.com/029496_polyphenols_green_tea.html
Bottled green tea and canned drinks: Why more harmful than healthy. (2006-2010). Retrieved from
http://www.amazing-green-tea.com/bottled-green-tea.html
Chinese tea health benefits. (2005-2010). Retrieved from
http://www.goldenteahouse.com/health_benefits.php#bac
Cold tea vs hot tea health benefits: How long can you keep or steep? (2006-2010). Retrieved from
http://www.amazing-green-tea.com/cold-tea.html
Compestine, Y. C. (2000). Introduction. In Cooking with green tea (pp. 2-3). New York, NY: Avery Books.
Cup of green tea to keep the bacteria away. (2007, January 16). ScienceDaily. Retrieved from
http://www.sciencedaily.com/releases/2007/01/070116132946.htm
Green tea. (2007). In B. Baver (Ed.), Mayo clinic book of alternative medicine (p. 56). New York, NY: Time.
Herbal remedies. (2010). Retrieved from Resort health products website:
http://www.resorthealth.com/herbs/green_tea.html
Lash, R. (2007). The legend of green tea keeps a-growin. Discover. Retrieved from
http://discovermagazine.com/2007/oct/the-legend-of-green-tea-keeps-agrowin/?searchterm=health%20&%20medicine%20nutrition%20te
Learn all about the history of green tea. (2010). Retrieved from Adagio Teas website: http://www.green-teasguide.com/history-of-green-tea.html
LIPTON® green tea with citrus flavor. (2010). Retrieved from Unilever website:
http://www.liptont.com/our_products/iced_tea/ice_green_citrus.aspx
Strep mutans. (2010). Retrieved from http://www.dentist.net/strep-mutans.asp
Tai, J. (2006-2010). The truth about tea: A t-volution is quietly steeping away. Retrieved from
http://www.amazing-green-tea.com/index.html
Thank you!