Keeping it fresh: An overview of refrigerated cargo

Reefer containers are the unsung heroes of global trade. Each one silently maintaining the perfect climate for its fragile cargo to thrive while en route to its destination. But what exactly do these specialised refrigerated containers transport? And how do they keep your favourite foods and essential supplies in tip-top condition despite their differing requirements? Let’s explore.

What types of goods are transported in reefer containers?

Reefer containers (also known as reefers) are designed to maintain precise temperature and humidity levels. By creating the ideal microclimate for the cargo in their charge, they preserve its quality and safety. In doing so, they also enable compliance with strict regulations and standards, such as those outlined by the International Organization for Standardization (ISO).

Here is a breakdown of the most common types of cargo shipped in refrigerated containers.

Fresh produce

Fresh produce means fruits and vegetables that have not been processed. With their adjustable temperature and humidity controls, reefer containers mimic ideal storage conditions for each type, slowing down the ripening process and ensuring freshness.

As the below examples of fresh produce illustrate, the temperature range within which each type must be stored and transported to maximise shelf life varies significantly.

Meat and seafood

Safeguarding food quality is paramount, especially for this category. Reefer containers maintain consistently low temperatures, preventing bacterial growth and ensuring these products reach their destination safely. Since fresh meat and seafood spoil quickly, it is important to prevent thawing or refreezing during transport.

As with fresh produce, different meat and seafood products require different temperature settings while in transit.

Dairy products

Milk, cheese, and other dairy products rely on precise chilled environments to prevent spoilage and maintain quality. Cold chain logistics ensures these items arrive at their destination in the best possible condition.

Pharmaceuticals

Life-saving medications, particularly biological therapeutics such as vaccines, require strict temperature control throughout transportation. Refrigerated containers guarantee the efficacy and safety of these vital supplies.

• Medications: Many medications, especially biologics (e.g., insulin, chemotherapy drugs), require specific temperature ranges (typically 2-8°C) and humidity levels (40-60%).
• Vaccines: Temperature-sensitive vaccines require precise temperature control within a narrow range (often 2-8°C) to maintain potency and efficacy.
• Cryogenics: Some pharmaceuticals and biological material (such as stem cells and organs) require specialised cryogenic containers and sophisticated temperature control systems for transportation. They are extremely sensitive to temperature fluctuations, and it’s crucial to maintain ultra-low temperatures below -150°C. Even minor variations render products unusable.

Other temperature-sensitive cargo

The world of cold chain logistics using reefer containers extends beyond the kinds of cargo you might expect. Here are some other items that rely on cold chain logistics.

• Fresh cut flowers: Maintaining ideal temperatures (typically between -1 and +4°C) and humidity levels is crucial for keeping flowers fresh and vibrant.
• Electronics: Sensitive electronic components can be susceptible to damage from extreme temperatures. Reefer containers create a stable environment, safeguarding delicate parts during transport.
• Art and antiques: Priceless works of art and historical artefacts are sensitive to heat and humidity. Reefer containers provide the necessary climate control to protect these treasures during transport.

Yet other examples of products requiring temperature control include chocolate, bonsai trees, potted plants, animal hides, and certain chemicals. These general guidelines outline the optimum conditions for the transport and storage of 100s of commodities. It is worth noting, however, that actual requirements may vary based on the specific product, its origin, maturity, and intended destination.

Did you know? The earliest recorded delivery of refrigerated cargo dates back to 1878, when 80 tons of mutton arrived in perfect condition at the port of Le Havre, France.

Beyond temperature-controlled cargo: How else do reefer containers protect goods?

Temperature is not the only important climate factor that must be well-regulated during transportation. Depending on the cargo, refrigerated containers also need to enable precise control of humidity and/or fresh air exchange levels. Fresh-cut flowers, for example, require good air circulation to allow them to breathe and prevent stagnant, moist air from causing spoilage.

What is the difference between ambient, chilled, frozen, and deep-freeze foods?

Understanding the specific needs of these different cold chain freight categories is important for proper food storage, safety, and quality. Here’s a breakdown:

Temperature categories for reefer cargo

Reefer container technology: How innovation is driving advancements

To optimise the shelf life, quality and safety of temperature-sensitive goods, refrigerated containers employ several key technologies. This is where leading logistics services providers set themselves apart – by developing highly accurate, efficient, and cost-saving systems that outperform other suppliers in safeguarding the quality of their clients’ temperature-sensitive cargo.

• Precise temperature control: Powerful refrigeration units maintain precise temperature control within the container, ensuring that products are kept within their optimal temperature ranges. Integrated sensors continuously monitor internal temperatures, providing real-time data to operators.
• Humidity control: Dehumidification systems help regulate humidity levels, preventing condensation and ensuring optimal conditions for various products.
• Controlled Atmosphere (CA) systems: For certain produce (e.g., apples, grapes), CA systems adjust the levels of oxygen and carbon dioxide within the container, slowing down ripening and extending shelf life. Controlled air circulation helps maintain even temperature distribution and prevent localised temperature variations within the container.
• Remote Container Management (RCM): GPS tracking enables real-time monitoring of the container’s location and allows for proactive intervention in case of unforeseen delays or disruptions. With data logging, one can record temperature and humidity data of the transit, providing a detailed history of the conditions within the container.

Companies like Maersk are constantly developing new technologies for reefer containers, such as more efficient refrigeration units, improved temperature control systems, and enhanced data analytics capabilities. Advancements in cold chain like supply chain visibility and automation are revolutionising cold chain logistics, reducing food loss, and enhancing efficiency.

Other innovations focus on delivering superior climate conditions for specific product categories. Examples include:

• Combining CA technology with “Controlled Ripening” (CR) capabilities to enable banana ripening during transit; and
• Deploying advanced insulation and refrigeration technology to keep high-value seafood products (such as tuna, shellfish, swordfish, and urchins) at ultra-low temperatures (-60 to -20°C).

Whether it’s pineapples from Costa Rica or fish from Spain, Maersk enables you to ship a wide range of temperature-controlled cargo worldwide. With our cold chain logistics solutions and end-to-end integration capabilities, we can help you maintain the quality and freshness of your cargo, while providing full traceability and visibility across the supply chain.