Carrier Refrigeration

Another component that should be controlled is ethylene, a hormone produced by all fresh produce that can accelerate decay, aging and ripening in the confined space of a refrigerated container. In addition to lowering respiration, a controlled atmosphere system should remove ethylene in an active way to avoid its harmful effects. Carrier Transicold's XtendFRESH ™ system is an example of technology that can monitor and control O2 and CO2 and remove ethylene. The XtendFRESH system does not require external ethylene filters or disposable scrubbing material, which distinguishes it from other systems for container atmosphere control. Controlled atmosphere technology can considerably increase the transit life of many fruit and vegetable cargoes by slowing down their metabolic rate without affecting eating quality and nutritional composition. Handle with Care Although controlled atmosphere is excellent for transit life extension, it can only realize its full potential when the commodity is harvested at the right age and optimum maturity, precooled properly and quickly, handled correctly, packed properly, processed under sanitary conditions, transported at the recommended temperature and atmospheric composition for each commodity, and cold-chain compliance is maintained. Existing, affordable controlled atmosphere systems are based on creating the correct atmosphere through product respiration. Establishing the desired levels of O 2 and CO2 in a timely manner after closing the container is highly dependent on how fast the commodity respires and the potential leak rate of the container. Success depends on the type of commodity being shipped and using an airtight container. An XtendFRESH type of controlled atmosphere system works best for high-respiring commodities like bananas, avocados, mangoes, asparagus, snap beans and raspberries. Some commodities that are low-respiring, such as grapes, blueberries, cherries, apples, peaches, papaya, kiwi and cantaloupe, require lower O 2 or higher CO2 than may be possible to achieve with the standard technology. For them, it may be necessary to inject nitrogen or CO2 into the container prior to departure to establish the desired levels. An alternative to controlled atmosphere technology is the use of modified atmosphere packaging. With this, the product is packed in plastic bags of specific permeabilities to O 2 and CO2 that are tailored to each particular commodity. The advantage is that the benefits of controlled atmosphere can be extended all the way to the store display shelf. However, extra care must be taken because when the product is exposed to temperature fluctuations, as normally occur during distribution, it can heat up, leading to accelerated softening. And, water condensation inside the bags can accelerate decay and spoilage. Designing the right controlled atmosphere protocol and using the proper controlled atmosphere system will help extend transit life potential of fresh produce. This can also help to reduce quality claims, while ensuring arrival of products in top condition to more distant consumer destinations. w Eduardo Kerbel joined Carrier Transicold Global Container Refrigeration in 2015, building on a 29-year career focused on postharvest business practices for private industry and government and as an educator. Today, he works closely with our customers representing many facets of the global cold chain – growers, shipping lines, logistics businesses and leasing companies – sharing his knowledge and experience to help them advance their success in transporting perishable goods from farm to consumers everywhere. *This article was developed for Food Logistics magazine as part of its continuing "Cool Insights" series. Look for additional contributions from Dr. Kerbel in future issues of Food Logistics and ContainerLINE. As a supplement to good temperature control, controlled atmosphere technology can potentially add days or even weeks to transit shelf life for a large number of fruits and vegetables. XtendFRESH ™ | ContainerLINE November 2017 5

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