Precooling Fruits and Vegetables in Georgia
Fruits and vegetables begin to deteriorate after they are harvested and separated from their growing environment. The rate of deterioration defines how long they will be acceptable for consumption. This is known as “shelf life.” To preserve the quality of fruits and vegetables and maximize profits for growers, it is critical to control the temperature of fresh produce and minimize the amount of time that products are exposed to detrimental temperatures.
Both temperature and relative humidity are important during the postharvest handling of fruits and vegetables. Heat, in particular, decreases produce quality and reduces market shelf life. Heat damage can come from two interrelated sources: the field’s temperature at harvest and the produce’s natural respiration. High field temperatures raise product temperatures; therefore, it is important to cool produce as rapidly as possible to avoid tissue damage. Some products that are sensitive to temperature abuse can experience excessive weight loss when field temperatures are too high. Some growers harvest their products at night to avoid excessive daytime heat. The second source of heat comes from natural respiration. Fruits and vegetables are still alive after they are harvested and they react with oxygen to form carbon dioxide, water and heat. Although this “heat of respiration” varies with different fruits and vegetables, in general as product temperature increases, respiration and heat generation also increase, shortening the shelf life.