Caffeine is present in many types of food and drink. The caffeine content of various beverages and foods can vary considerably, even between batches of the same product.
Factors affecting caffeine content:
(1) type of beverage or food (such as chocolate)
(2) caffeine content of botanical source
(3) volume or amount ingested
(4) preparation - instant vs brewed vs prolonged brewing
(5) intentional alterations – decaffeination vs supplementation
Sources of variation in a brewed cup of coffee:
(1) volume (typically 6 or 8 ounces)
(2) type of coffee (and caffeine content)
(3) preparation of the grounds (roasting, grinding, etc)
(4) amount of coffee grounds brewed
(5) manner and duration of brewing
Brewed coffee has approximately 16-18 mg of caffeine per ounce. 17 mg per ounce will be used in the implementation.
Regular brewed tea has about a third of the caffeine content (6 mg caffeine per ounce), but the caffeine content is affected by the same variables as for brewed coffee.
Decaffeinated does not usually mean caffeine-free. A high volume of a decaffeinated coffee that is brewed can contain a sizable amount of caffeine. Decaffeinated coffee tends to have < 2 mg of caffeine per ounce (< 0.08 mg per mL).
Many colas have the same amount of caffeine as tea.
