Perfectly sanitized dimpled spinach leaves or tender greens like baby lettuce has been high on the wish list of the $3.1-billion bagged salad industry since its inception. The race to develop better wash systems for cleaning took off in earnest in 2006, after the high profile E. coli O157:H7 outbreak linked to bagged spinach killed five people and sickened more than 200 , leaving the leafy green industry with a black eye and an ego-bruising $350-million price tag in recalls and lost sales.