ii) Ripening with Ethylene gas: In this technique, the fruits are exposed to low level of ethylene gas (10-100ppm) in an air-tight ripening chamber for 24 to 72 hours so as to induce ripening. The most important thing in this technique is temperature and relative humidity control inside the ripening chamber, which should range between 15-250C and 90-95% relative humidity, depending upon the fruit type. Several methods are used to provide proper ethylene concentration in the ripening room.