Its the natural Ethylene gas that's the catalyst of the ripening process. Quite a miracle really. Of course man has now learned how to pick hard green Tomatoes, ship them across the globe in a shipping container, then inject manmade Ethylene into the the shipping container and ripen the whole lot in a week or two! No thanks!! I"ll stick to my in season, in garden, Purple Cherokees!!!! :hobbyhors