VuFind's import tools include support for using the Aperture Java library to extract full text from external documents (PDF, Word, etc.). In order to take advantage of this, you need to install Aperture (see link below) and point VuFind to the software by editing the web/conf/fulltext.ini file.
For more details of using Aperture in VuFind, see the import instructions for MARC and XML documents.
Under Linux, there is a known bug with version 1.5.0 which prevents Aperture from running on the command line correctly. See this page for details on the fix (it just involves minor edits to the lcp.sh file).