stripping code from listing

Hi,

I’m getting excerpts like

Geskryf deur Francois van Deventer [caption id="attachment_161" align="alignleft" width="664" caption="Esters, Jongelinge, Bekommerdes"][/caption] Die middag van 25 Oktober het die Jongelinge (jeug), die

Bold by me to highlight the problem.

The text is generated by this code: (as far as I can tell)

<?php the_content_rss(”, TRUE, ”, 50); ?>

I’m using the GracioMag theme.

How could I strip the unwanted code?

Thanks