- var_dump: documentation ( source)
- preg_replace_callback: documentation ( source)
- str_replace: documentation ( source)
<?php
$article = '"foo bar baz" bat "quux quuz" this little "piggy" went "to market, this little" piggy "STAYED HOME!"';
$article_clean = preg_replace_callback('/".*?"/', function($v) { return str_replace(' ', ' ', $v[0]); }, $article);
var_dump($article_clean);