You’re going to produce a leaflet entitled: “Everything looks brighter after a cup of tea – Fact or Fiction”. It will explain all the health risks and benefits of drinking tea. You will substantiate any of your claims by investigating tannin, caffeine and flavonoids in tea. You will carry out analytical tests on tea samples and your leaflet should be able to list a number of different types and brands of tea with the findings from any tests explained.
Before you start your investigation you should carry out a risk assessment and have it checked by your teacher. For help with this, read through our health and safety information and look out for health and safety warnings in the text.
You should start by looking at the range of teas that are available. You will need to pick a wide selection of types to test, try choosing a range of different types and brands of tea.
First, you need to do some research to find out what tannin is. Find out what it does to your cup of tea – both in appearance and flavour. Find out if it has any other uses. Does it have any harmful/beneficial effects on health? Find out if any teas give information about their tannin levels on the packaging. Design a test to determine which of your tea samples contains the most tannin. When you’ve got some rough, comparative results, find out how to determine actual quantities of tannin in tea samples. You will need to investigate protein precipitation and spectroscopy. When you’re up to speed with the method you should set about determining the tannin levels in your tea samples. You may need to link up with a university or someone from industry if your school/college doesn’t have the appropriate equipment.
Next up is caffeine. There’s a lot of literature available about why too much caffeine is bad for us. Conduct your own research and collate your findings. Try also to find out if caffeine is beneficial in any way. Find out if any teas give information about their caffeine levels on the packaging. Pick decaffeinated as well as caffeinated teas to test. Design some tests to see if drinking caffeine can affect performance.
Only conduct these tests if you have written permission from the subjects. Don’t use more tea or more cups of tea than people would normally consume. Make sure the tests are done hygienically.
Work out if it’s possible to determine the caffeine levels in your tea samples. You will need to find out about High Performance Liquid Chromatography (HPLC). You could also determine the caffeine levels in a variety of coffees. Which contains more caffeine, tea or coffee? You will almost certainly need to link up with a university or someone from industry to use HPLC–equipment.
Flavanoid and fluoride content
Tea contains flavanoid, a type of polyphenol. Find out about the health benefits of flavanoids. Find out if any teas give information about the number/amount of flavanoids on the packaging. It is possible to determine the polyphenol content of your tea samples. However, you won’t be able to conduct such tests in your school/college (or even a university); stick to researching the methods. Polyphenols are extracted using 70% methanol/water solvent. The content is determined by a method called ‘Folin Ciocalteu spectrophotometry against gallic acid standards’. Tea also contains fluoride. Find out the health benefits/risks of fluoride. Find out if any teas give information about the amount of fluoride on the packaging. As with flavanoids, determining the content of fluorides won’t be possible within a school/college. Again, research the methods and, if possible, contact someone in industry to demonstrate them.
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