Fruit Damage Due to Ammonia Refrigerants
- Ammonia refrigeration is very common today in the fruit storage industry. The basic principles involved are the same as any other refrigeration technique, except that ammonia is used instead of freon or other fluids. Ammonia as a refrigerant combines a number of desirable properties: It's inexpensive, readily available, has a low boiling point and a relatively high heat capacity. Unlike chlorofluorocarbons, ammonia does not contribute to ozone depletion. Cooling the fruit helps to prevent it from spoiling prior to sale.
- Accidental low-concentration leaks from the refrigeration system can leach ammonia gas into the chamber where the fruit is being stored. Once the concentration of ammonia exceeds 50 mg per 100 ml or 0.05 percent, the ammonia may damage the fruit. Ammonia has a strong and unpleasant odor that becomes readily apparent even at these low concentrations. The odor of ammonia should be taken as a sure sign that a leak has occurred.
- The symptoms of damage in fruit are similar to those caused by some other chemical agents, including excessive exposure to fumigants. The ammonia damages the skin and tissue of the fruit and its appearance. Dark surface stains and black discoloration are common symptoms of ammonia exposure. Low concentrations cause tiny green-black specks. Higher concentrations may cause even more serious injuries like pitting and scald, and the discoloration may extend all over the surface of the fruit.
- Ammonia refrigeration systems are usually equipped with ammonia sensors that detect trace concentrations -- often the first sign of a leak. Many insurance companies require certification that ammonia sensors have been installed and are functioning properly. Appropriate detection and ventilation systems are essential. It's vital to ensure that employees are trained on the use of this equipment; they should all know how to recognize and respond to a leak. Detection and ventilation systems should also be inspected frequently and repaired as necessary.