bibtex-autokey-titleword-case-convert-function

bibtex-autokey-titleword-case-convert-function is a variable defined in `bibtex.el'.
Its value is

downcase

• This variable may be risky if used as a file-local variable.

Documentation:
Function called for each titleword to perform case conversion.
See `bibtex-generate-autokey' for details.

You can customize this variable.