Desenvolvimento e avaliação de filme biodegradável de polietileno incorporado de amido de grão-de-bico (Cicer arietinum L.) / Development and evaluation of biodegradable film of polyethylene incorporated with chickpea starch (Cicer arietinum L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The concern with the pollution caused by the great volume of waste plastics in the environment has led to the study of new biodegradable materials. The starch is one of natural polymers with greater potential of application in the development of biodegradable packaging, which is renewable and can be obtained from much variety of crops at low cost. Chickpea is promising for the use in films, mainly for its high quantity of amylose. The aim of this study was to extract and characterize starch from chickpea and use it to produce a biodegradable film of polyethylene. Chickpea starch yield was of 28%, having high purity. Scanning electron micrographs revealed cylindrical and oval granules, with mean length and width of 20 μm and 10 μm, respectively. X-ray pattern could be assigned to a C- type starch, typically of legume seeds. Pasting properties from chickpea starch were measured using differential scanning calorimetry (DSC) and rapid visco analyzer (RVA). The DSC parameters such as onset temperature, conclusion temperature and enthalpy of gelatinization were 65.51C, 86.90C and 12,12 J/g, respectively. Pasting temperature evaluated from RVA was 73.1C and was observed high viscosity values and set-back and low shear thinning. Chickpea starch showed low swelling power and solubility at 90C. Starch gel showed high turbidity values and syneresis and, at texture profile analysis, were observed high compressive force and springiness. The heating resistance, high paste viscosity and good capacity to form gel could be related to a great potential to use chickpea starch for films that suffer high pressure and temperature during processing. Polyethylene films incorporated with 5, 10, 15 and 20% chickpea starch and plasticized with 2.5% of acetyl tributyl citrate (ATBC) were processing at a single-screw extruder. Films with less starch concentration presented good appearance and well gelatinized granules and that ones with more starch had structural problems because of not totally gelatinized granules. The incorporation of starch in the PE films resulted in increase of the opacity and it did not provoke alteration in the crystallinity pattern and the glass transition temperature. In terms of mechanical properties, the films with starch showed a characteristic of a rigid and brittle material, losing the elongation capacity. The films had lost weight in the biodegradation tests at soil and water, of 3% maximum after 90 days, with trend of increase with the time. It had growth of fungus in the films embedded in soil and algae in that submerge in water. The microorganisms had initiated the degradation for the starch points, provoking formation of holes. The control film (without starch and with plasticizer) showed to have incompatibility between ATBC and PE, with loss of the plasticizer for the environment. The chickpea starch allowed the formation of plastic films, with better mechanical properties and appearance at lowest concentrations, and increased the biodegradation at the environment. More studies are necessary for its application as food packaging.

ASSUNTO(S)

propriedades funcionais functional properties chickpea starch amido de grão-de-bico tecnologia de alimentos filme biodegradável biodegradable film

ACESSO AO ARTIGO

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