Filmes biodegradáveis de amido de trigo mourisco (Fagopyrum esculentum): produção e caracterização utilizando a técnica de Casting com adição de ácidos orgânicos

Abstract

Packaging materials are crucial to ensure the safety and quality of food throughout its shelf life. Petroleum-based plastics and flexible films represent the vast majority of packaging sold; however, their widespread use has significant disadvantages for the environment. The industry's interest in biodegradable films has been increasing in a context in which there is a growing concern about the disposal of plastics in the environment. Chapter I highlights the study and application of biodegradable starch films from non-conventional sources in the context of food, where it has stood out as an option that fits into conventional waste disposal models while aiming to add value to underutilized crops. The study of non-conventional sources of starch for the production of edible films is a constant trend in the area of food science and technology, as well as studies to improve mechanical properties and sensitivity to water, in order to close the gap to synthetic plastics efficiency. The objective of chapter II was to investigate the influence of the incorporation of organic acids (citric, malic, and tartaric) in buckwheat starch films obtained by casting. Buckwheat starch was extracted using alkaline methodology and the impact of different acids and concentrations on film properties was evaluated. The films obtained were characterized by their mechanical properties and moisture resistance, water vapor permeability (WVP), as well as thermogravimetric analysis (TG), field emission source scanning electron microscopy (FEG-SEM) and infrared spectroscopy (FTIR). The incorporation of organic acids resulted in reduced moisture content (up to 21%), WVP (up to 2 times) and increased thermal stability, suggesting the occurrence of crosslinking reactions with polycarboxylic esterification. From the organic acids studied, films prepared with tartaric acid and citric acid resulted in improvements in mechanical and water resistance, while malic acid in general provided films with undesirable mechanical properties and surface homogeneity - especially at higher concentrations - probably due to its characteristic to promote the intramolecular interactios. Buckwheat starch films with tartaric acid showed significant improvements in WVP and thermal stability, maintaining mechanical resistance and with greater elongation when compared to films without organic acids. Based on the results of this study, the incorporation of tartaric acid into buckwheat starch films has demonstrated application potential, especially in situations where the product needs to be protected from environment humidity, but with high dissolution upon final application (i.e. edible films or products to be dissolved in water). On the other hand, the incorporation of citric acid formed a film with intermediate and improved properties compared to films without organic acids. A few studies applying buckwheat starch as a source for film production are found in literature, and to date no published studies have been identified regarding its interaction with different organic acids, therefore the novelty of this thesis.