Bananas ripen naturally or through an induced process. Once picked they can turn yellow on their own provided that they are fully mature by the time they are being harvested, or can be exposed to ethylene gas to induce ripening. Bananas which are turning yellow emit natural ethylene which is characterized by the emission of sweet scented Esters. Most retailers sell bananas in stages 3–6, with stage 5–7 being the most ideal for immediate consumption. The PLUs used for Cavendish bananas are 4011 (yellow) and 4186 (small yellow). Organic Cavendish bananas are assigned PLU 94011.