However, the major issues highlighted by the recent crisis turned renewed attention on the question of sustainability, and especially how hard-pressed economies intend to deal with increased pressures on their supply chains. After all, the inevitable further squeeze on costs is going to affect everyone, and above all those whose businesses are marginal at the best of times.
Shipping food around the world, particularly perishable and delicate fruits and vegetables, is an intensely competitive business where margins are measured in small percentages. In this context, controlled atmosphere reefers play a vital role: not just in ensuring that high-value cargos reach their destination in perfect condition, but in maximising energy efficiency and minimising costs for operators.
As natural products, fruits and vegetables are still alive after harvesting and continue to consume oxygen (O2) and release carbon dioxide (CO2) as they ripen. The key to slowing down the ripening process, and thus extending the transportation window, is controlling the supply of O2 and the extraction of CO2. Left to freely consume O2 inside unregulated reefer containers, the produce would become rotten long before completing the voyage.
With properly regulated atmospheric control, however, even the most delicate fruits, such as avocados, bananas and blueberries can easily survive anything from 28-45 days in transit and still arrive in perfect condition.
Passive beats active
There are two basic approaches to controlled atmosphere technology: passive and active. The active system injects nitrogen (N2) into the reefer to reduce CO2 levels more quickly. However, the process is more complex and costly and requires additional flushing to achieve and maintain the correct balance of gases for specific fruits. Besides which, with voyages of up to 40 days or more, the benefit of rapidly reducing CO2 levels to the desired set point is negligible.
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