Desenvolvimento de filmes biodegradáveis contendo compostos bioativos das cascas de Euphorbia umbellata (PAX) Bruyns (Janaúba)

Abstract

There is a growing concern about the amount of waste produced from non-biodegradable packaging. Their high consumption intensifies its production, which generate more waste. The use of biodegradable polymers from renewable sources becomes an alternative to this problem. The incorporation of antioxidant substances into plastic films, such as plant extracts rich in antioxidant and antimicrobial components, for the protection and maintenance of food quality, has been researched due to its abundance in nature. The objective of this work was developed active biodegradable packaging formulated with cassava starch, glycerol and extracts of Euphorbia umbellata bark (known as Janaúba), and after, evaluate the obtained material by their thickness, solubility, density, opacity, thermogravimetric analysis (TGA), scanning electron microscopy (FEG), determination of total phenolic compounds, antioxidant activity (DPPH •, ABTS • + and FRAP) and antimicrobial activity. Euphorbia umbellata (hexane, chloroform, ethyl acetate and methanol) fractions were initially extracted and the quantitative determination of the phenolic compounds, antioxidant activity (DPPH •, ABTS • + and FRAP) and antimicrobial activity of fractions was performed. The phenolic quantification revealed that the acetate fraction had the highest amount of these compounds (515.81 ± 0.02 mgGAE / g), better antioxidant activity against the DPPH experiments (1.95 ± 0.00 IC 50 μg / mL ), and higher antimicrobial potential against the strains of microorganisms tested (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Salmonella enterica ATCC 14028). These results demonstrated that this fraction was promising for incorporation into the cassava starch film. The results showed that the incorporation of the acetate fraction of the Euphorbia umbellata peel into the films influenced their thickness, solubility, density, opacity and whiteness index. The thermal analysis (TGA) of the films showed lower degradation temperature of the polymer matrices with the addition of acetate fraction. The microscopic evaluation of the films showed that, due the addition of the acetate fraction, a change in the regularity of the polymer matrix occurred and the film surface became more heterogeneous. For all the films produced with the addition of the acetate fraction, the development of antioxidant activity (DPPH •, ABTS • + and FRAP) could be observed, which was proportional to the concentration of the fraction used. The starch films, incorporated with different concentrations of acetate fraction of the Euphorbia umbellata bark, showed positive results for the antimicrobial activity measured by diffusion method in agar, presenting zones of inhibition for Staphylococcus aureus ATCC 25923 and for Escherichia coli ATCC 25922, and did not presenting zones of inhibition for Pseudomonas aeruginosa ATCC 27853 and Salmonella enterica ATCC 14028. Based on this, is possible conclude that the biodegradable cassava starch-based films, incorporated with the Euphorbia umbellata bark extract, presented bioactive properties and physicochemical characteristics suitable alternative for the production and application in food packaging.