After product has reached ripening temperature ethylene gas is added. The gas can be added with three systems. 1) A patented ethylene generator produces ethylene from ethyl alcohol. It produces a relatively constant flow of gas for atleast 24 hours. 2) pure ethylene can be purchased in small pressurized cylinders holding three cubic feet of gas. The cylinder is opened in the room providing a rapid release of gas, which will provide an adequate level during the process, if the room is fairly gas tight. 3) For larger operations use ethylene gas available in larger cylinders and use flow meters to measure a prescribed amount into the room.