San José, Costa Rica, since 1956

Banana Plastic: A Novel Idea

If the concept of biodegradable plastic sounds light years ahead of Costa Rica, imagine biomedical pins that dissolve inside patients’ bodies and San José vehicles running on biofuel – all made out of rejected bananas.

The recently released results of a study by the National Science and Food Technology Center (CITA) of the University of Costa Rica and the National Banana Corporation (CORBANA) revealed that bananas that do not meet export standards can be used to produce much more than just juice and purée.

According to a statement from the  National Council for Scientific and Technological Investigation (CONICIT), the number of rejected bananas amounted to 322,000 tons in 2005, approximately 20% of the national banana production.

Of this number, 75% is processed and converted to juice, pulp and purée, while 25% is used for national consumption, said the statement.

However, CITA’s revolutionary experiment could transform this, changing the use of refuse bananas to production of raw materials for biotechnology.

CITA director and project researcher Carmela Velásquez, who affirmed the project is a breakthrough and bananas have never been evaluated for this use, said she and her research collaborators, Rebeca López and Ana Ruth Bonilla, found the fruit has two significant applications: production of polylactic acid and ethyl alcohol, or ethanol.

During a recent press conference at CORBANA’s research facility in the Caribbean-slope town of Guápiles, Velásquez explained that polylactic acid, used to make biodegradable plastic, is the product that most interests researchers.

“This plastic is attractive for biomedical applications. Instead of a metal fracture pin that will set off all airport detectors, the body will absorb it (the biodegradable pin). You don’t have to remove it,” Velásquez said during the press conference, adding that this type of plastic is very malleable, too.

The acid can be produced only through microbiological fermentation, a procedure through which the fruit is ripened, turned to pulp, and then submitted to a fermentation process through a microorganism that converts the banana’s sugars into lactic acid.

Lactic acid is a colorless or yellowish liquid that results from lactose fermentation, which is commercially produced mainly from corn fermentation, according to CONICIT.

Ethanol, the other application of bananas, was produced by the food technologists with a laboratory bioreactor, a machine that induces fermentation to obtain alcohol, according to Velásquez.

The expert explained that although the production of ethanol and biodegradable plastic worked on a small scale, with compact machinery, it has not yet been tested on the industrial level.

 If ethanol production works on a massive scale, experts would want to use it as bioethanol, fuel combined with a percentage of ethanol that creates a more thorough combustion in the motor of a vehicle, resulting in less toxic emissions because of the oxygen content of ethanol, according to the CONICIT statement.

Ethanol is also produced through fermentation of other products such as sugarcane, potatoes, rice, wheat, and other cereals that are rich in starch.

CITA research on the use of banana waste began three years ago, with the financial backing of the Science and Technology Ministry, which contributed ¢23 million ($46,000), the Costa Rica-United States Foundation (CR-USA), a private nonprofit organization that supports development in Costa Rica, with ¢6 million ($12,000), and CORBANA, which donated ¢5 million ($10,000) to the experiment, according to Velásquez.

Minister of Science and Technology Fernando Gutiérrez, who attended the March 30 press conference, praised the researchers’ work as an example of how the business sector can help finance projects that will generate knowledge for their own use.

“This matter (financial support) cannot just come from the State, to produce this synergy, two parts must come together,” Gutiérrez said, explaining the two parts are the business sector and the country’s research community.

Banana producers, who harvest 99% of their fruit on the country’s Caribbean slope, have shown interest in the possibilities the project generates.



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