Caracterização dos rizomas filhos e da fécula do mangarito (Xanthosoma mafaffa Schott) e elaboração de filmes biodegradáveis

Abstract

Conventional packaging, especially plastics, constitute a significant portion of municipal waste discarded in the environment. Concerned with environmental issues, search centers, companies and governments come interesting and investigating the biodegradable packaging, derived from renewable sources as an alternative to minimize environmental impacts. In this context, this work, which was developed at the Universidade Estadual de Goiás (UEG) in Anapolis, Goiás, had as main objectve to study the physical and chemical properties of the comels the mangarito (Xanthosoma mafaffa Schott), properties physical, chemical and functional of starch isolated this and preparation and characterization of biodegradable films based on starch using glycerol as plasticizer. Initially the physical characterization, chemical composition of rhizomes and the of starch granules of these isolates were determined, as well as the granule morphology, size, paste viscosity in rapid viscosity analyzer and thermal properties by differential scan calorimetry. Later, starch was used for preparation of biodegradable films, keeping constant the amount of this (2 g) varying the mass of the filmogenic solution (FS) and the plasticizer [glycerol (GLY)] in the solution, following a scheme experimental central composite, star type, with five replicates the center point and four axial. And in the end, characterized the biodegradable films on the visual appearance by means of microphotographs, thickness, water solubility and water vapor permeability. We applied a mathematical model predictive of the dependent variables (solubility and permeability), using analysis of variance (ANOVA) at 5% probability, its optimization was performed by the proposed technique for dependent variables based on the definition of a desirability function (D) restricted the range of [0,1] and the experimental data were described using means and standard deviations, being processed and analyzed with the help of statistical analysis program Statistica 8.0. It was observed that the rhizomes have an average weight of 3,5 g, the average major and minor diameters of 23 and 15 mm, respectively, are highly energetic, consisting mainly of starch and does not oxidize in contact with air, presenting suitable for the production of starch. The isolated starch showed purity of 95,19% and its granules shape rounded and average size of 12,5 μm. It was found that the gelatinization temperature of starch is between 82,15°C and 94,65°C. The viscosity profile of starch pastes showed high stability at 95°C and a greater tendency to retrogradation, being indicated for use in the packaging industry, adhesives and food products. Applying the starch, associated with water and glycerol in the preparation of biodegradable films was noted that variations in glycerol concentration and thickness did not influence the visual appearance of the same and the conditions which the FS were submitted were sufficient to obtain films biodegradable homogeneous. In characterizing the films as the thickness, the water solubility and water vapor permeability can be observed that the thickness, which has values between 0,035 to 0,081 mm, varied significantly depending on the concentration of glycerol and the amount of film solution (p < 0,01), not depending on the interaction of factors and the effect was positive, may reach a maximum of 0.086 mm for 30% GLY and 25 g of FS and a minimum of 0,036 mm for 10% GLY and 19 g of SF. In assessing the solubility and permeability showed that the respective values between 9,24 and 36,22% and 5,55 x10-5 to 12,75 x10-5 g (ms Pa) -1, it was found there is interaction of glycerol versus mass of filmogenic solution and depends on the synergistic effect caused by these factors, the maximum achieved 48,20% solubility and 14,28 x 10-5 g (ms Pa) -1 permeability in films prepared with 30% glycerol and 25 g film solution and has already achieved the minimum of 8,75% solubility in films prepared with 10% GLY and 20 g of FS and 6,31 g (ms Pa) -1 permeability in films prepared with 10% GLY and 22 g of FS. Considering the desirable factors of low water vapor permeability and thickness and high solubility, films made with 10% glycerol and 24,73 g film solution would be those who would attend more of these characteristics.