Is replacing certain words with certain adjectives better by regex or pure Python?

I wonder if the following can be done reliably by regex, or should I stick to plain string manipulation in Python? Performance is very important.

German apple is good. Apple is nice. Where is the apple? English apple have worms. English people are nice.

• I would like to replace all occurrences of Apple or apple with German apple.


• However if apple has the adjective English, English should be replaced by German.


• English people won't change, because people aren't apples.

I am not really an expert in regex. There are some online generators, such as this http://www.regexr.com/

I tried this and it gives me only the first apple. \b(apple)

Any help would be much appreciated