Carrier Refrigeration

What is meant by postharvest? Postharvest is the handling of all fresh produce – fruits, vegetables, and flowers – after harvest. It's the management of the product through the entire cold chain. More than just the transport of perishables, the cold chain is preparing the product at the packing plant in the producing country, putting it into the right packaging and into the container or cargo hold, starting refrigeration, putting it into transit, and when it arrives at the destination, continuing with proper handling to the ripening facility or distribution center, and then on to the retailer. The essence of postharvest technology is to try to stop the natural process of ripening, senescence, aging and breaking down to make sure the fruit maintains top quality from the time it is harvested until it reaches the consumer. How important is temperature in the postharvest period? Refrigeration is key, and cooling the fruit as soon as possible after harvest is crucial. The most complex operation of the cold chain is within the country of origin: harvesting the fruit at the right maturity, processing it at the right speed, loading it on the same day and making it to the ship on time. So managing the product through the cold chain is much more than simply turning on the refrigeration at the vessel. That said, fruits, vegetables and flowers typically spend 80 percent of their time after harvest in transport and would not survive the travel without optimum refrigeration. What limits the ability to preserve produce after harvest – either in storage or transport? The main biological activity of any fruit, vegetable or flower from the time of harvest until it dies and deteriorates is respiration. Refrigeration is the main way to keep respiration as low as possible. The more respiration can be brought down, the longer fruits, vegetables and flowers can be kept. Each product has its own metabolic activity, and that's why some have more potential for shipping long distances than others – it's their genetics. That's one reason why bananas can last for more than 30 days, but raspberries only about five, with traditional refrigeration alone. Are there other factors that can limit transport of perishables? The maturity of the fruit, flower or veggie at the time of harvest is a factor. If you wait too long, you reduce shelf life potential. If you were to harvest tomatoes when they were red, they would not last through shipping. You have to harvest them green, like bananas. This allows them to reach destination markets in good condition, where ripening can then be completed, as needed, for commercial sale. Any wounding can speed up respiration tremendously. The bruising of fruits tends to release internal production of ethylene, a powerful hormone that is involved in many processes and will accelerate the ripening. Other factors are humidity, presence of mold and the anatomy of the tissue of the fruit itself. Some, like bananas, have more protection than others. How does equipment play a role? First, it must be ensured that the product is kept at the optimum, minimum safest temperature. The proper temperature for each flower, fruit and veggie is known, but many times temperature is not enough. Ethylene also needs to be prevented from building up, so that the freshness of the product can be maintained for a longer period of time. The atmosphere around the produce can be artificially modified by lowering oxygen and increasing carbon dioxide. In doing this the products are put to sleep by slowing down respiration. In addition, preventing water loss helps to prevent dehydration, decay, senescence and rapid ripening. For most fruits, this can be achieved by maintaining high levels of humidity. Should the technologies used to ship produce matter to retailers? Definitely. Controlled atmosphere helps the product maintain its quality and freshness during transit, and increases the potential for a better shelf life at the destination market. The big retail companies need to understand the benefits of an option such as XtendFRESH and know that they can take advantage of it if they simply specify that shipping lines use the controlled-atmosphere technology to deliver their imported perishables. w Turn to the Expert | ContainerLINE 2015 11

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