Summary The ripening of Blue cheese may be accelerated by the addition of to the milk or to the curd. Approximately the same degree of flavor development was secured in five months in cheese to which commercial (Pfanstiehl) was added as in normal cheese in twelve months. While the steapsin cheese was accepted by the trade, competent judges considered it inferior to the normal cheese due to a characteristic bitter flavor. Cheeses made with but which were not inoculated with mold became quite rancid and developed none of the typical flavor of Blue cheese. Although may accelerate the ripening of Blue cheese, it cannot produce the characteristic flavor of the cheese, unless Penicillium roqueforti is present and active.