Why should we even ask the question? Because coffee is made out of coffee beans – they are called "beans" and all sorts of beans are kitniot (as we discussed). But what we discussed as "beans" are seeds in the botanical family Leguminosae. Coffee beans may look a bit like beans, but luckily they come from a totally different family, the Rubiaceae.
Coffee was considered for prohibition on pesach, on the argument that it is "a seed that people eat". On the other hand, coffee grows on trees and tree fruits are not included in the minhag of kitniot. Also, coffee it is not grown or stored near to grain and it is processed in a totally different way than your typical grain (ever bought "coffee bean flour"? No? Thought so). And finally, it was not included in the original minhag, as coffee arrived in Europe only in the 17th century. Also – the people just like coffee, so it would not be possible to enforce a prohibition. Dan Rabinowitz has a fascinating article on his blog about who (tried to) ban coffee when for what reason.
So while plain black coffee is always ok for pesach, Rabbi Dovid Cohen from the CRC lists some concerns that might bring coffee into contact with chametz. As the first possible problem, he lists decaffeination, where some of the used chemicals might be derived from chametz (whether or not you hold that this is actually a problem is another story). Second, instant coffee might contain maltodextrin which might be made out of chametz (but as instant coffee tastes horrible anyway, I’m glad not to be forced to drink it). And third, you never know what "flavor" actually is. So, to sum up – drink your coffee black, like Captain Janeway, and you will be fine.
- Danger of chametz traces: Not for plain black coffee.
- Danger of confusion with chametz (raw): No.
- Danger of confusion with chametz (processed): No.
- Botanical categorization: Rubiaceae, flower
- Known in 13th century: No.
- Verdict: Not kitniot.
photo (c) Photographer Robert Knapp http://www.modernartphotograph.com