Protecting Horticultural Commodities Exposure to moderately low temperatures Exposure to low temperatures can also harm products. For example, certain fruits and vegetables - mainly those of tropical and subtropical origins, are susceptible to damage called chilling injury when exposed to temperatures above their freezing points but below 41°F to 59°F (5°C to 15°C). Symptoms of chilling injury include internal discoloration, surface lesions, failure to ripen properly and increased susceptibility to micro-organisms. The extent of chilling injury depends on the temperature, duration of exposure and the sensitivity of the product. Some commodities may show chilling injury only after prolonged storage while others may be injured by brief exposure to low temperatures. To prevent chilling injury, it is essential to know each product's recommended temperatures for pre-cooling, storage and transit. The following is a partial list of commodities sensitive to chilling injury
Exposure to freezing temperatures Freezing injury results when commodities are held below freezing temperatures. Typically freezing injury makes the product unfit for consumption. Most tropical and subtropical products are damaged by chilling injury before they freeze. The role of temperature in respiration Respiration rate is governed by temperature. For every 18°F (10°C) rise in temperature, the respiration rate doubles or triples, though it also depends on the different commodity variety, area of production and growing conditions. The transit life of a commodity is inversely proportional to its rate of respiration - the higher the rate, the shorter its transit or market life. Harvested commodities give off heat during respiration. This heat must be considered when designing the refrigeration equipment and determining the ventilation requirements. Proper temperature management will retard the respiration process and remove heat from the load. In summary, when it comes to the transportation of perishables, factors like temperature control, air exchange, proper packaging and loading become extremely important. Pre-shipment consideration
The effect of bruising on respiration It is important to prevent bruising from field to market, since bruises serve as entry points for decay. Bruising also accelerates the respiratory activity of the plant tissue, leading to faster heat release, aging and shorter potential shelf life. |
The quality of the perishable produce intended for shipment should be checked and inspected for proper maturity, skins breaks, bruises, decay and other deterioration. Another important factor is whether the commodity is able to withstand the transit period, of course in consideration of the intended transportation temperature. In general, the maturity and temperature of the produce should be measured prior to shipment. 