Caffeine is present in some quantity in over than a hundred plants, but only the fruits of coffee, cocoa, cola nut and tea leaves contain plenty of it. Caffeine content in a cup of coffee is influenced by several factors:
- Beans roasting degree: more roasted (darker) beans, as for espresso, give less caffeine.
- Coffee sort: Robusta beans contain more caffeine than Arabica.
- How to brew coffee: the less coffee contacts with water, the less caffeine it contains, so a cup of espresso brewed in 28 seconds contains less caffeine, despite the existing stereotype.
Remember that caffeine does not affect the taste of coffee, thus thinking that bitter taste of coffee means it contains more caffeine is a mistake. The bitter coffee is not necessarily strong, and vice versa – the strong is not necessarily bitter! The bitter taste is added by complex organic substances — tannins. To neutralize them, milk or cream is added, they fix tannins and the brew loses its bitter taste. The caffeine is considered a moderate stimulant that effects the central nerve system via regions of the brain.
The coffee doesn’t only stimulate a person, but also helps to overcome sleepiness. It increases productivity. Caffeine alkaloid improves reaction and helps to concentrate.
Stimulating the heart, the caffeine increases stroke output, accelerates respiration and metabolic processes in the whole body. Thus, it helps vessel relaxation, increasing blood flow in all organs. At the same time it stimulates constriction of blood vessels of the brain, causing brief increase of blood pressure.
Since 1958 coffee has been listed as a product and drink considered safe for human health by World Health Organization. Caffeine is eliminated from the body completely. Healthy adult can drink 2-3 cups of coffee a day (it is even considered a therapy dose for a healthy person).
Chemical composition of roasted coffee beans.
| Food products | Caffeine content (mg) |
|---|---|
| Can of Coca-Cola | 30 |
| Cup of tea | 30 – 50 |
| Plain chocolate, (100 g) | 20-200 |
| Headache medicine with caffeine | 25-100 |
| Cup of espresso (60 ml) | 40-100 |
| Cup of machine brewed coffee (150 ml) | 50-175 |
| Cup of Arabica (150 ml) | 50-120 |
| Cup of Robusta (150 ml) | 100-250 |