Caffeine doesn't taste of anything. Extracted, it's a tasteless, dull white powder that has some resale value for caffeine pills and caffeinated drinks thanks to its stimulant properties. In other words, it doesn't add anything to the taste of coffee. As everything else in this world, it is a chemical, one that can be analysed and understood - and can therefore be targeted by other chemicals or processes for removal from its carrier.
The most interesting carrier of caffeine is, of course, coffee. Whilst tea is a culturally vital plant that also contains caffeine (roughly half the quantity of coffee when comparing the the drinks), coffee has a deeper culture of drinking for stimulation of the body rather than of conversation.
Decaffeination, whether by carbon filter or using solvents such as methylene chloride or ethyl acetate (the latter of which exists in fruits such as apples and pears, leading some marketers to refer to a "natural" decaffeination process), requires initial processing of the green beans to enable the caffeine to be extracted. This is usually done by steaming, but can also involve compressed CO2. Whatever the case, the bean fibres are broken open for "attack." Beans are also re-steamed to remove any remaining solvents and are then roasted. These preparation and finishing processes lead to weaknesses in the bean structure that lead to sensitivity to the roasting process.
As far as I can understand, the somewhat underwhelming taste of most decaf coffees is a result of there being a higher likelihood of individual beans within a particular roasting batch becoming over-roasted and imparting a burnt, unfulfilling taste to the blend. For this reason, decaf coffees tend to be light to mild roasts that naturally cannot give the "bang" that a high roast can.
Whilst coffee decaffeination is still an imperfect art, it is very much a luxury for many that would be denied those who cannot or should not consume caffeine.
All of this is a prelude to me voicing my intense annoyance at the fact that the small coffee stall in the Heidelberg Kinderklinik doesn't sell decaffeinated coffee at all. Yes, those young mothers looking after their breastfeeding children are denied this one crucial luxury that allows them to escape the hospital environment, no matter how briefly, with an intense taste experience that is all too often denied them during their stay there.
As a postlude, it will be interesting to see how genetically selected (see how awful that appears these days? But how else do we get our most beautiful flowers or treasured dogs?) caffeine-free beans work out, commonly known as
decaffito.
