Caracterização físico-química de filmes biodegradáveis de farinha de mandioca e proteína de soja

Abstract

Environmental concerns associated with plastics disposal have promoted research into alternatives to replace the common plastic. Following this tendency, this research used cassava flour mixed with different rates of soybean protein and glycerol to produce biodegradable films by thermoplastic extrusion. Variables analyzed were: soybean protein, moisture and glycerol. The analysis was done by using a methodology that consists in surface response statistical design to obtain predictive mathematical models. The variables were response to water vapor permeability (WVP), output pressure extruder (MPa), flow rate (kg/h), the thickness film (mm), the penetration force (N), the penetration deformation (%), the traction tension (N), the tensile strain (%), elasticity modulus, Water Solubility Index (ISA, %), Water Absorption Index (IAA, g gel/g), color (L, a, b), maximum pasting viscosity at low temperature (Cp), maximum pasting viscosity (Cp), minimum pasting viscosity (Cp), breakdown pasting (Cp), final pasting viscosity (Cp) and Setback pasting (Cp). The raw materials were characterized for their proximate composition. The variance analysis showed that the water content and the soybean protein are significant linear with respect to the WVP (P <0.05). Pressure to exit from the extruder, the water content was the most significant variable, followed by glycerol, and the flow, thought to be a significant inverse effect on the interaction of water and glycerol content. With respect to the films thickness, there is great significance for the water content in both a linear and quadratic followed by the protein content of soybean and glycerol. For the penetration force all variables were significant. While penetration for deformation in the interaction between glycerol and water content and the interaction of soybean protein and water content were inversely significant, none of the independent variables was significant for the traction tension. With respect to the interactions of independent variables on the tensile deformation, there was a significant reverse. In the elasticity modulus calculation, the interaction between glycerol and water content and the interaction of soybean protein and water content were significant in direct proportion again. In WSI, the greatest significance was given by the soybean protein, followed by glycerol. With respect to WAI, there is not significance of independent variables. For color, only the parameter b, the glycerol showed a significant inverse square. In the starch rheology analysis, it was observed that glycerol and water content were significant linear and quadratic relationship with cold pasting viscosity. The interactions between glycerol and water content and the interaction of soybean protein and water content were inversely proportional in the maximum, minimum and final pasting viscosity. The water interaction and protein content of soybean showed significance with respect to the breakdown and Setback pasting. The fact that the protein concentrations and glycerol have values or not significant in a smaller proportion compared with the water content as to its effect on the dependent variables analyzed, may be due to the model proposed mergers have been insufficient. Therefore, the addition of glycerol at higher percentages undermines the extrubility .