This was told to me by a Turk & it works. When the Bananas appear to start turning a lighter green, cut the bunch off and place in a black bag with a light coloured apple, not red or dark green. Place the bag on the floor in a darkened room allowing air to get into the bag, but not allowing the light to get in. check every few days and you will see your bananas ripen, 7 to 14 days should do it, depending on the lightness of the green when you put them into the bag.