Serving with different mime types

[eluser]Clooner[/eluser]
I want to serve my application with a different mime type then normally I would use a php code similair. This is how I would do it normally.

Code:

header("Vary: Accept");
if (stristr($_SERVER["HTTP_ACCEPT"], "application/xhtml+xml"))
    header("Content-Type: application/xhtml+xml; charset=utf-8");
else
    header("Content-Type: text/html; charset=utf-8");

or I could also set it with apache and the extensions.

My question is: Is there a way with codeigniter config to set a different or default mime-type which is not text/html?