I agree with Ben. Just accept the local politics. Every group has their peculiarities. I've been told by some groups that coffee is an intoxicant and thus forbidden by the fifth precept. What is considered not "food" and therefore acceptable after noon varies. Some groups worry whether the "bits" in a juice are too large and sieve their juices. I've been with Ajahn Chah groups who have dark chocolate (and gummy bears!) in the evening, which would be frowned on by other groups.
The point of this precept, in my view, is to enhance mindfulness and concentration. I don't think that the details of exactly what is allowable are particularly important.
However, as Ben says, suddenly dropping coffee can be tricky. I gradually weaned myself off coffee onto green tea on a retreat in January... As my energy went up I didn't need the coffee anymore...