Obtención de plásticos biodegradables a partir del almidón de judías verdes y amarillas para su aplicación en envasado de alimentos

Abstract

The aim of this work was to obtain bioplastics using starch extracted from green and yellow beans (Phaseolus vulgaris L). For the development of the work, the starch was extracted by the wet method and natural decanting using a factorial design, where the factors were time and grinding speed with high and low levels. Subsequently, the quality of the starches obtained was analyzed. For the elaboration of bioplastics, tentative formulations were first elaborated with each starch separately and then they were combined with the objective of establishing process parameters. Then, a factorial design was elaborated, having as factors the concentrations of starch (3.80g and 3.60g) and glycerin (3.50g and 3.00g), resulting in four formulations (constant acetic acid and distilled water). Thickness, humidity, solubility, permeability, mechanical properties and biodegradability tests in water, surface and soil were carried out on the sheets obtained. The influence of these factors on the characteristics of the sheets was analyzed with the help of the MINITAB 19 statistical software. The starch extraction yields were poor (less than 2.00%) for both legumes, their amylose concentration was high, 42 .50% yellow beans and 50.13% green beans. A bioplastic sheet with 0.13mm thickness, 16.65% humidity, 37.94% solubility, 0.0195gm-1h-1MPa-1 permeability, 17.34MPa modulus of elasticity was obtained as the best formulation, 4.04% elongation and a biodegradability in water and soil of 90% from day 15. The bioplastic obtained presented an ideal hermeticity for food packaging, but its handling was very complex. It was concluded that bean starch was high in amylose and suitable for these studies, the plasticizer was the most important variable in the physical and mechanical characteristics in the synthesis of these biodegradable products. Modification of the starch and use of another less hydrophilic plasticizer is recommended.