It is very difficult to increase relative humidity above your already very high humidity, but there are some things you can try.  Usually the major reason for moisture removal from the room is the refrigeration evaporator coils.  Coils should have a large surface area and be controlled to operate at the highest possible temperature.  Second, the temperature of the room and fruit must be very uniform.  Surfaces inside the degreening room with temperatures even one degree Celcius lower than your set point temperature will be subject to condensation and will consequently remove moisture from the air.  You will need to do a temperature survey to find any cool areas in the rooms.  If you find cold areas, they are probably caused by poor air circulation.  Improving air circulation may help increase humidity.  Another reason for cold surfaces is inadequate insulation.  This would contribute to low humidity when outside air temperatures are low but would have little effect when outside temperature is near room setpoint.   Third, remove any materials that absorb water.  Fruit should be in containers made of plastic not wood or corrugated fiberboard.  Finally check the calibration of you humidity instrument.  Very few units have good accuracy at high humidities. I hope these suggestions help. – Jim Thompson