Avaliação do efeito do sorbitol e do glicerol nas características físicas, térmicas e mecânicas da película e do hidrogel de amido de milho reticulado com glutaraldeído

Abstract

Starch is used in food industry as a thickener and stabilizer, in addition, has apart from degradability and mechanical properties that enable their use in the production of biodegradable films. Due to these characteristics the starch has the potential to replace conventional packaging, as well as an alternative to reduce environmental impacts by non-degradable polymers derived from petroleum to reducing the environmental impact caused by the non-petroleum degradable polymers. Few studies have used Waxy corn starch as a basis of byopolymer´s production owing to low amylose. Waxy corn starch has not been enough studied as a basis for the production of biopolymers, because it has a low amylose content. However, this ingredient is a low cost hydrocolloid low cost which can be used in industry. As the mechanical condition of biodegradable films and hydrogel based on starch are fragile and poorly resistant it becomes necessary to add plasticizers and crosslinking additives thus allowing its applicability. Therefore, this study evaluated the addition of 2-simplex lattice 2 simplex lattice, hydrogel systems and biodegradable film to the crosslinked corn starch with 0.75% glutaraldehyde, varying the concentration (0 to 30%) of the plasticizers glycerol and sorbitol. The influence of the application and concentration of additives glycerol, sorbitol and glutaraldehyde on the hydrogel starch properties of starch hydrogel was characterized by gelation kinetics analysis (by turbidity), differential scanning calorimetry (DSC), flow curves (rheology) and compression (texturometer). The results obtained from the proposed analysis, showed that the final hydrogel product may have been thixotropic and pseudoplastic characteristics, high rigidity and opacity. The increase in sorbitol concentration moved to an increase in the hydrogel breakdown voltage, making a stronger and resistant gel. Since a high concentration of glycerol increased its elongation, forming a more elastic gel. Thermal analysis proved that the addition of additives delayed gelation, the outstanding result in systems containing high concentrations of sorbitol. Nevertheless, the applicability of this system for upstream production of biodegradable films was limited by the formation of fragile and brittle films characteristics.