Bioplásticos: síntese e caracterização de plástico biodegradável à base de amido extraído do córtex da mandioca (Manihot esculenta Crantz)

Abstract

The use of plastics derived from petroleum results in two major dilemmas: they depend on a non-renewable and therefore finite source of material, and the second is due to the fact that they are made up of polymers that are resistant to natural degradation and generate serious environmental impacts. In this scenario, the so-called bioplastics are presented as a promising alternative, since they have properties similar to conventional plastics and, at the same time, are less harmful to nature and present socioeconomic advantages. In this sense, from the perspective of sustainability, the final project in question aimed to synthesize a bio-based and biodegradable bioplastic and evaluate its potential for applications in coating fruits and extending shelf life. The bioplastic was produced using the casting technique, which consists of preparing a film-forming solution to form the biomaterial of interest. The raw material used in the synthesis was the cassava cortex (Manihot Esculenta Crantz), from which the starch was extracted through mechanical processes. The plasticizer and solvent used were commercial glycerol and distilled water, respectively. The quality of the bioplastic was evaluated through the following properties: thickness, opacity, solubility, moisture and biodegradation in soil. To verify the potential of the final product in the packaging sector, an immersion test was performed on cherry tomatoes (Solanum lycopersicum var. cerasiforme), and their ripening was monitored by means of the variation of TSS available in the pulp. The technique employed and the materials used demonstrated efficiency for the production of bioplastics with characteristics similar to other results described in the literature. The values for thickness, opacity, solubility and moisture were equal to 0.24 mm (± 0.11); 2.29 (± 0.04); 29% (± 0.029) and 8.99% (± 1.20), respectively. The biodegradation test in soil showed a reduction in the size of the samples and proliferation of fungi on the surface of the material, revealing the capacity of the material to undergo biodegradation. The evaluation of the material as packaging demonstrated its inefficiency in delaying the ripening of cut tomatoes, as it favored the growth of fungi, while for whole fruits it showed promise; however, more in-depth tests are necessary. The present study demonstrated the viability of using cassava bark as a source of starch for the production of biobased and biodegradable materials with properties similar to previous research, with potential for application in the packaging sector. It is also concluded that the methods employed are aligned with the principles of green chemistry, in order to contribute to a more sustainable society.