Keeping It Cool

Before cool chain logistics in sea freight was ready for the market, an unconventional step needed to be taken: seven years of research on the high seas, in specially reconverted containers, were necessary for this rapidly developing transport mode to overcome its teething troubles. Read on to find out how a young researcher faced this challenge and what cocoa beans had to do with it.

In the year 2012, around 190 million t of chilled cargo were transported around the world, around half of which was shipped in refrigerated container vessels across the sea. By 2016, global refrigerated transport volumes had risen to 2.87 billion t, and industry forecasts predict that they will reach 3.25 billion t by 2022. The amount of technological innovation and economic significance behind these numbers becomes apparent when one stops to take a brief look back.
 

It all started with bananas

The arrival of the sailing ship "Reyward" in New York in 1803 with 30 red banana trees from Cuba is commonly seen as the first example of modern reefer vessel transport and of what we understand as cool chain logistics today. During the first few decades, reefer transport was almost exclusively centered around bananas. In 1850, they were increasingly coming from Central America as well, and imported to the USA via Boston, New York and New Orleans. The only problem was that the banana trees were shipped as additional cargo on the decks of slow sailboats, which resulted in around 60% of the bananas ripening prematurely and having to be discarded into the ocean. By as early as 1880, when Siemens presented the first electric elevator and Thomas Alva Edison patented an improved light bulb, meat had become the most important refrigerated commodity worldwide, which it would remain for the next 80 years. By this time, the industry had learned a few lessons and made significant success – first by using ice as a coolant, then by means of cold air from cooling chambers or brine-filled pipes running through the cargo area and absorbing the heat from the cargo.
 

Fancy a steak from Argentina?

In order for foodstuffs transports to bridge more extreme distances, such as between Australia and Europe, another large leap of innovation was needed. In 1874, the first steamboat equipped with a vapor compression cooling system – aptly named “La Frigorifique” – managed a successful meat delivery from Buenos Aires to the French Rouen. With this, the proverbial ice was broken. In the following decades, reefer ships and cargo refrigeration systems were continuously improved and optimized. To this end, methods that had already been tried and tested on land – such as the ones contained in our ordinary refrigerators – were adapted to the special requirements of ship operations. 

The world in 6.06 x 2.44 x 2.59 meters

In April 1956, when the American transport entrepreneur Malcom McLean’s first container ships embarked on their journey from Port Newark, Pennsylvania, to Houston, Texas, it was not yet apparent that a revolution had taken place: In the following decades, container shipping grew into one of the most important pillars of world trade. Not least thanks to its particular suitability for various types of breakbulk cargo, which could now be transported simultaneously, independently of their shapes or specific storage requirements – at drastically reduced prices. 

The reefers (short for “refrigerated containers”) which were introduced shortly after brought significant additional benefits. They made it possible to close the cold chain and bring even small load quantities safely into new target markets by means of intermodal transport.

Quality over quantity

Despite technical innovation, shorter delivery times and increasingly precise know-how, the preservation and quality of chilled products have remained the dominant issue up until today. Even modern cooling systems have their pitfalls, after all. And over-refrigeration can wreak just as much havoc on taste and quality as a lack of refrigeration.

The founder of the US ocean carrier Sea-Land and aforementioned “inventor of container transport” Malcom McLean set out to tackle this problem with an unconventional solution. He installed a container laboratory on one of his ships where he wanted to analyze foodstuffs and the changes they underwent under genuine conditions and under direct, live supervision. He found the perfect expert for this endeavor in the young scientist Barbara Pratt, who had just gained her physics degree at Cornell University in New York in 1976.

Life and research in the container

The research environment: a container with three compartments - consisting of a machine room with diesel generator, fuel tank and water tank; a laboratory; and an office and living section with desks, bunk beds and cooking facilities. 

The first challenge: cocoa beans which were shipped from the Dominican Republic to the USA and arrived moldy. 
The discovery: Solar radiation during the day caused the temperature in the containers to rise, drawing the moisture out of the beans. As soon as the containers cooled down at night, the water would condense and drop back into the bags of cocoa beans, causing mold to grow. 
The consequence: a new ventilation system for containers, which solved the problem.

Barbara Pratt spent a total of seven years working in the container laboratory and producing important findings for elementary questions of cool chain logistics, such as regarding temperature, humidity and ventilation. She analyzed numerous types of fruits and vegetables as well as their sensitivities and reactions under various circumstances. 

It is easy to imagine that research on this topic is significantly simpler today, or at least, can be conducted without spending weeks inside a container. With the help of modern computers, the calculated values do not need to be permanently monitored, and analyses can now be made remotely, as Barbara Pratt explains in an interview. Meanwhile, Pratt has remained true to her vocation: Today, she is Experienced Refrigerated Transportation Executive at Maersk Inc., the market leader in container shipping who had taken over Sea-Land in 1999. A job description which fits her perfectly.