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What color is fungi?

The traditional manioc (also known as cassava), a native plant from the southeast of the Amazon Region and the staple food of Brazil’s indigenous people, had been used as food long before the arrival of the Portuguese explorers. Cassava now has new and advanced technological functions. Biodegradable plastic films made from the starch of this vegetable can be used to produce active packaging, capable of preventing the growth of fungi, or intelligent packaging, which changes color when the food product begins to spoil. This polymer is also being tested in heart surgery to coat venous implants and provide them with higher resistance during the initial phase or to release drugs.

The studies that resulted in the plastic films made from cassava, a polysaccharide whose main function is storing the energy produced by photosynthesis, began in 2004 at the University of São Paulo (USP). The films, developed by the research group coordinated by Professor Carmen Cecília Tadini from the Food Engineering Laboratory of the Chemical Engineering Department of USP’s Polytechnic School, share a common element, which is the addition of glycerol during the composition of the film. Glycerol is a plasticizing substance, commercially referred to as glycerin. A low-cost compound, glycerol is a by-product of biodiesel.

This research group has conducted studies on three types of plastic films, each one characterized by the substances in their compositions. Two of the films contain clay nanoparticles to make them more resistant. In the case of the antimicrobial film, the substances include clove and cinnamon oils, which provide protection from microorganisms. Laboratory tests with the polymer containing these oils revealed that the polymer prevents the growth of fungi. “Nowadays, anti-fungi substances are applied to the packaged product for protection,” says Carmen. “The assays we conducted on the films that we developed showed that this protection lasts for up to seven days.”