Improve the_content and the_excerpt_rss filter

/*
 * RSS
 */
// Add a Custom Field to WordPress RSS
if ( recipressextend_recipress_version_check() ) {
  add_filter('the_excerpt_rss', 'recipressextend_postrss');
  add_filter('the_content', 'recipressextend_postrss');
}

function recipressextend_postrss($content) {
  global $wp_query;

  $postid = $wp_query->post->ID;

  $recipe = get_the_recipe_extend( $postid, 'rss' );

  if (is_feed()) {
    if ($recipe !== '') {
      $content = $content . "<br /><br /><div>" . $recipe . "</div>";
    } else {
      $content = $content;
    }
  }

  return $content;
}

Improve this code because when i used Seriously Simple Podcasting plugin, it was overwriting it’s feed.

https://wordpress.org/plugins/yakadanda-recipress-extend/