I saw this today, and I was wondering if anybody had heard of this or had more info. According to this, the Fresh Express ready washed salads have been using this technology since the end of May. It mentions something of using lactic acid, and peroxy-something acids.
http://danacosolutions.net/news/news.article.php?newsid=340
http://danacosolutions.net/news/news.article.php?newsid=340