Limiting the number of words displayed from custom fields

I am using custom fields and some code I found to display them alongside each entry on the homepage.

This is the code:

<?php
      $profile = get_post_meta($post->ID, "profile", true);

      //check that we have a custom field
      if ($profile != "")
      {
        // Separate our comma separated list into an array
        $profile = explode(",", $profile);

        //loop through our new array
        foreach ($profile as $profil)
        {
          echo $profil;
        }
      }
?>

The custom ‘orofile’ field typically contains quite a lot of text and I’d like to be able to limit the number of words when I display its contents on the homepage.

Essentially, I’m trying to recreate the way the built-in Excerpt function works, but apply that same idea to custom fields.

I’ve searched for a plugin or some code to help me do this, but can’t seem to find anything.

I’d really appreciate any suggestions anyone has. Thanks.