There are over 60 species of coffee currently in existence, but only two are of main commercial value. Namely, Coffee Arabica or "Arabica" and Coffee Cenaphora or more commonly known as "Robusta" coffee. On average caffeine content in Arabica is 1.2% (range 0.9-1.4%) and 2.2% in Robusta (1.8-4.0%).
Contrary to popular belief, coffee is not bitter due to caffeine, but rather due to the formation of several protein containing compounds created during roasting. In fact, its been estimated that less than 10% of coffee's 'bitterness' can be attributed to caffeine alone.
Melanoidins are brown colored polymetric compounds created during roasting process and responsible for giving coffee it characteristic brown hue. It accounts for approximately 25-30% of coffee's dry beverage and has been identified as a potent antioxidant, generally higher in medium color roasts.
Methylene chloride (CH2Cl2) is the most common method of decaffeination, representing 50-75% of the decaf market. The method is sometimes referred to as the KVW method or European process. A large percentage of the coffee is still decaffeinated in Germany since this is where much of the technology originated.
"Chemical free" decaffeination refers to the removal of caffeine without the use of traditional chemicals, namely methylene chloride or ethyl acetate.
There are several "chemical free" methods currently on the market with the most popular being the patented Swiss Water method, Mexican Water process, and Super Critical Carbon Dioxide method. The first two use water as a solvent used to extract caffeine from the bean, whereas the super critical method uses naturally occurring compressed CO2 gas as the solvent.
Naturally decaffeinated coffee is coffee decaffeinated using ethyl acetate (C4H8O2), a naturally occurring compound created during the ripening of several fruits.
Although manufactures label coffee as "naturally decaffeinated" the truth is that the solvent is produced synthetically. In pure form ethyl acetate exists as a clear volatile liquid with a fruity smell. It is also used in a number of industries including perfumes, nail removers, and in the storage of insects (entomology).
Produced by a mycotoxin Aspergillus ochraceus, OTA is short for "Ochratoxin A". Thus far, researchers have identified three distinct strains of the toxin: ochratoxin A, B and C, though only ochratoxin A has been associated with coffee.
OTA has been under extensive research over the past decade, since studies have shown to cause renal tumors in animal models. Currently the toxicity of OTA has been debated, since studies have shown its inability to form reactive intermediates in humans.
OTA formation in coffee has been correlated with poor manufacturing practices, namely: poorly stored cherries, improper drying, and rewetting of the beans on drying patios. Cases have also been found in poorly processed decaffeinated coffee samples.
Although OTA exposure from coffee is minor, it accounts for an estimated 4% - much behind its occurrence in other products, including cereals (44%), wine (10%), and beer (7%).