Development of a biodegradable film based on chestnut starch

• Autor(a) principal: Fontoura, Ana Catarina Quintino
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.22/24076
• topic: Chestnut starch; starch-based films; biodegradability; food system; Life cycle assessment; Domínio/Área Científica::Engenharia e Tecnologia

Conventional plastics, known for their durability and versatility, have generated serious environmental problems. Their characteristic of not easily degrading results in the massive accumulation of plastic waste in oceans, soils, and landfills, causing environmental pollution. In addition, the production of conventional plastics from oil contributes significantly to carbon dioxide emissions, exacerbating climate change. To address these environmental problems, biodegradable plastics have emerged. They are designed to decompose more quickly in specific conditions, such as industrial composting or natural environments, which helps to reduce the accumulation of plastic waste. In addition, many biodegradable plastics are derived from renewable sources such as plants, decreasing dependence on non-renewable resources and reducing CO2 emissions during production. This work aimed to develop a chestnut starch-based film reinforced with fibers from the chestnut shell. The first step was to compare the efficiency of three extraction techniques: High Shear in Water method using deionized water (Sdw), High Shear in Water method using tap (Stw) and extraction using Na2S2O5 (Ssm). High Shear in Water method using deionized water (Sdw), showed a slightly better yield was with means of 26.67%. However, the chestnut starch extracted by the High Shear in Water method using tap water (Stw) showed greater similarities with the commercial potato starch (CS). To produce the films, an alkaline extraction was carried out on the chestnut shells to obtain fibers which were then bleached. Four different films were prepared by the solvent casting technique, using four types of starch: CS, Sdw, Stw and Ssm. The obtained films were characterized regarding some mechanical, optical, and functional properties. Its biodegradability and application to a system food were also evaluated. The film in which the migration of the phenolic content from the food (toast) to the film was higher was the FCS. Elongation percentage varied between 4.32 ± 0.14 % (FCS) and 9.64 ± 0.70 % (FSsm). Tensile Strength varied between 1.25 ± 0.19 (FStw) and 2.08 ± 0.01 (FSdw), while the elastic modulus varied between 13.90 ± 3.67 N/mm2 (FSsm) and 40.06 ±3.15 N/mm2 (FCS). The film prepared with Ssmwas the most biodegradable, with around 15 % of mass loss after a 5-weeks in contact with soil. Life cycle analysis was realized to help determine the more environmentally safe method of starch extraction. The results showed that the Stw was clearly the more sustainable extraction method.