The Fast Food Fruit
Technology: The banana’s journey from the plantation to you is one long science project.
BY GLORIA DAWSON
A truck is traveling on the freeway. Inside, stacks of bananas are piled high. Picked a few weeks ago at a plantation, they’ve traveled overseas in climate-controlled cargo ships, their color still green and unappetizing. But that won’t last for long. A colorless gas with a faint, sweet, and musky odor seeps from an open pouch placed inside the truck, quietly transforming the fruit en route. By the time the tropical fruit is in your grocery basket, they are a golden yellow.
This is not science fiction, but yet another attempt at perfecting the tropical fruit delivery process—a new ripening-on-the-go trick that Professor Bhesh Bhandari and his Ph.D. student Binh Ho at the University of Queensland, Australia, are now experimenting with. For the past two centuries, bananas have traveled the world by all modes of transportation. In the late 1800s, it was by railroads—tracks were built solely for banana transport. In the 1900s, bananas were trekked in refrigerated ships—gleaming white fleets with radio technology that allowed vessels to coordinate their arrival times with harvesting schedules. In his book, Banana: The Fate of the Fruit that Changed the World, Dan Koeppel says that the banana industry “invented fast food in a way.” A banana may be healthier than a burger, but how it’s brought to you is not all that different. Before the fast-food industry learned to process, pack, and ship inexpensive temperature-controlled meals, banana carriers had already perfected their own shipping process. “If you look at the model of the industrialized supply chain, what they really came up with was a lot closer to what a fast-food chain does,” he says. The result “is bananas that arrive at the market on their final green day, and which will last exactly seven days before turning brown.”
By the time bananas land on the supermarket shelf, their ripening process has already been carefully engineered through the use of three gases: ethylene, carbon dioxide, and oxygen. “To bring this tropical fruit to distant markets and have it be edible is kind of amazing,” says Randy Ploetz, a professor of plant pathology at the University of Florida. “It’s pretty much a science.”
It is indeed. The banana is “a climacteric fruit, which means that once the ripening process begins, you can’t stop it,” explains Ploetz. “So the idea is to harvest the fruits when they are mature but not ripening.” When banana bunches are cut off at harvest, they start to release ethylene, triggering a decrease of pectin and a breakdown of starch, which softens and sweetens the fruit. As part of that “senescence process,” Ploetz adds, bananas also release carbon dioxide. But high levels of carbon dioxide and ethylene would cause bananas to ripen too fast or to spoil before they arrive to consumers. Like many other climacteric fruits, bananas are sensitive to carbon dioxide— if carbon dioxide levels rise to more than 7 percent, the fruit will soften while still green and won’t taste good. So the transportation companies use a full-blown climate-control system for their capricious passengers. When bananas are loaded onto a ship, they are cooled off to 54 to 58 degrees Fahrenheit, depending on the length of the future voyage, and the levels of oxygen and carbon dioxide are maintained at 5 percent each, according to Carrier Transicold, a company that designs trucks and ships to transport bananas worldwide. Plus, humidity levels are kept between 90 and 95 percent, to keep the fruit moist.
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