We don't treat our bags with anti-mold or anti-staining treatments, as they can be quite toxic.  To get rid of mold, spray it with distilled white vinegar.  After the bag has dried, use a soft brush and scrub the area with a mix of lemon juice, salt and hot water.To keep mold from coming back and to prevent it from growing, wash the bag fairly regularly and dry it completely before putting it away.  Make sure to remove the ice pack from the bag as soon as possible after eating.