Monitoring Storages

Cold-storage and CA facilities are monitored for temperature, RH, ammonia, oxygen, and carbon dioxide. Refrigeration equipment for cooling and maintaining fruit temperature should have reliable control mechanisms. Consistent, stable temperatures maximize storage life. Temperatures outside suggested ranges reduce expected storage life if too high or can lead to severe chilling or freeze injury if too low. An obstacle in managing RH is the ability to measure it accurately. Sensors for measuring RH include capacitive, resistive, thermal conductivity, and dew point instruments. The most reliable sensors are chilled mirror hygrometers that measure the dew point.

Specific cultivars of fruit have specific atmospheric requirements. Storage at a gas concentration that is 0.5 percent lower or higher than recommended can result in a commercial disaster. Some cultivars are very sensitive to carbon dioxide at concentrations above 0.5 percent. Thus, it is important to be able to monitor gas levels on a routine schedule, automatically control these gas levels within set points, and have storage operators on call 24 hours a day for emergencies. The sensors used for detecting oxygen are paramagnetic, polarographic, or electrochemical. Carbon dioxide sensors are normally infrared detectors. The latest technology of scanning near-infrared equipment has demonstrated the ability to monitor carbon dioxide and other important gases such as ethylene, carbon monoxide, propane, 1-methyl-cyclopropene, and various flavor components inside storage rooms. This equipment is quite expensive, but with a manifold system of solenoid valves and pumps, one scanning infrared sensor can monitor several rooms on a routine cycling basis.

The main objective in handling and storing freshly harvested fruit is to preserve quality through rapid cooling and cold storage. The most valuable tools for storage operators are accurate, reliable, and stable equipment that produce, maintain, and monitor cold-temperature and atmospheric conditions.



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