Challenges in Postharvest Procedures for Maintenance of Quality of Tropical Fruits and Vegetables

Tropical fruits and vegetables marketed in the U.S. are produced primarily in other countries and exported to the U.S. using marine transport. Challenges involved in exporting tropical fruits and vegetables to the U.S. are interrelated and include those related to the production environment and to the postharvest physiology of tropical crops. Many tropical fruits and vegetables are quite sensitive to physical injury during harvesting and postharvest handling. Postharvest decays are an issue since there are no labeled pesticides available for most tropical crops. An inherent problem in international trade of tropical fruits and vegetables is that long transit durations of 2 to 4 weeks, or even longer, may exceed the limits of the products¹ potential postharvest life. This is particularly problematic for fruits, because it may lead exporters to ship immature fruit with consequent poor sensory quality at the consumer level in the U.S. Average daily temperatures during harvest seasons in tropical production regions are typically quite high - commonly in the range of 30 to 40 °C. In addition, many tropical products are subject to quarantine for insect pests and the most common treatments required to address potential infestation involve heating the products with high temperature (in excess of 40 °C) water or air. This makes rapid cooling and excellent temperature management essential for successful export operations, but the required infrastructure for proper postharvest temperature management is often lacking. On the contrary, tropical fruits and vegetables can be injured by exposure for sufficient duration to low temperatures that are below a threshold unique to each product. This chilling injury is an issue in exporting tropical products because exporters may address transit durations that test the limits of their products¹ postharvest life by using lower than recommended set point temperatures in the marine containers during shipping. Since the sensitivity of tropical products to chilling injury is greater for lower maturity stages, the combination of immature products and lower than recommended transit temperatures can be devastating to product quality. These practices often result in produce that, while it has acceptable appearance upon arrival in the U.S., is very likely to later develop chilling injury in stores or in consumers’ homes.