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17 July 2012

Caffeine

This video from Periodic  videos arrived in my inbox this afteroon:

Published on Jul 17, 2012 by 
In our first video about caffeine, Dr Rob Stockman extracts the molecule from six cups of coffee. Video also features Professor Martyn Poliakoff and Dr Samantha Tang. 
From the School of Chemistry at The University of Nottingham:http://www.nottingham.ac.uk/chemistry/index.aspx

At the end of the video we learn that 17 milligrams of caffeine were in a filter drip cup of coffee....of course, I was curious about how much caffeine there is in other food and drink, for example -  a bottle of Coca-Cola, and chocolate. A little searching on Google revealed: 

"There is 96mg of caffeine in one litre of Coke Zero or Coca‑Cola and 128mg in a litre of Diet Coke. This equates to about 32mg in a 330ml can of Coca‑Cola and 42mg in a 330ml can of Diet Coke. To help put this in context, a mug of tea contains about 75mg of caffeine and a mug of coffee provides about 100mg of caffeine." (link)


Searching on, I came to this chart of Caffeine Content in Drinks, where you can sort by USA, UK/Europe, and Australia/NZ.  Explore this site a bit, and you'll find interesting graphs, charts, links, and comparisons. 
"The most comprehensive chart of beverage caffeine content online. Find the amount of caffeine in coffee, tea, soft drinks, energy drinks and energy shots.
Note that caffeine amounts are for the whole can/bottle."
It's hard to find out if cafeine content of various drinks is the same in the US as it is elsewhere, because the US content is listed in fluid ounces, and the rest of the world is in ml.  (1 US liquid ounce = 29.5735296875 ml)

WikiAnswers tells us that a 32 oz can of Coca-Cola Clasic contains 34 mg, "For comparison, green tea has about 25 mg per 12 oz, black about 50, and coffee can have upwards of 200 mg."   From the Australian Food Standards site we learnt that milk chocolate has 20 mg/100g bar, but the Lindt website says
"Caffeine is a natural compound derived from plant sources like kola nut and naturally found in substances like coffee and tea. However, very little caffeine is found in chocolate in comparison to the amount found in the other commonly consumed sources. Generally, 1oz of Dark Chocolate contains about 20 mg of caffeine 1 oz of Milk Chocolate contains about 6 mg of caffeine 1 oz of White Chocolate contains less than 2 mg of caffeine By comparison, an average can of soda contains about 50 mg of caffeine and the average cup of coffee approximately 80 ? 155 mg. The caffeine content will always vary, depending on the product and even in some cases depending on the specific cocoa bean and origin. "


So put on your math hats, and figure this out!
1 oz = 28.3495 gr
100 gr = 3.52739619496 oz
Fluid ounces are different from dry ounces...
Here are the various content descriptions:
32 mg in a 330ml can of Coca‑Cola
17 mg (milligrams) of caffeine were in a filter drip cup of coffee
100 mg in a mug of coffee
25 mg per 12 oz green tea
50 mg per 12 oz black tea
200 mg per 12 oz coffee
20 mg of caffeine in 1oz of Dark Chocolate 
6 mg of caffeine in 1 oz of Milk Chocolate
20 mg per 100g bar of milk chocolate

Are they all saying the same thing?