Development and characterization of films based on Canna indica L. flour / Elaboração e caracterização de biofilmes de farinha de biri (Canna indica L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The focus in biodegradable films is a global trend and has received a significant attention in recent years, thus motivating studies related to the development and characterization of films based on natural macromolecules. The objective of this study is to develop edible films from biri flour (Canna indica L.) and evaluate the effect of four process variables: glycerol concentration (15 - 35%), process temperature (70 - 90 °C), drying temperature (35 ¿ 55 °C) and drying air relative humidity (30 ¿ 70%), on both mechanical (puncture force, deformation, tensile strength, elongation at break and secant modulus), and optical (color, brightness and opacity ) properties, as well as on water solubility of films. In the first stage of this work, flour and starch were obtained from rhizomes of biri cultivated in the S? Paulo State (Brazil). The evaluation of such materials dealt with proximate chemical composition, physical and thermal properties, microstructural analysis by Scanning Electron Microscopy (SEM), size distribution of starch granules and structural analysis by Fourier Transform Infrared (FTIR) spectroscopy. On the second stage, edible films from the biri flour were prepared according to a Central Composite Rotational Design 24 (CCRD). The results were statistically analyzed using the response surface methodology (RSM), which along with the desirability function (D) allowed to obtain the optimum process conditions (17% for glycerol concentration, 90 °C for process temperature, 44,8 °C for drying temperature and 36,4% for air drying relative humidity). In optimum conditions the films showed high values of tensile strength (7,0 MPa), low solubility (38,3%) and satisfactory values of elongation at break (14,6%). On the last stage of this work, the films were prepared from flour and starch biri in order to determine the effect of fiber, protein and fat on the properties of the flour biofilms. The films were characterized based on their mechanical and optical properties, microstructure and structural analysis by means of SEM and FTIR. The results showed that flour films have greater flexibility in terms of elongation at break (14,6%), high water vapor permeability (5,3 ?0,2 x 10 -10 g.m/m2.h.Pa) and lower tensile strength and secant modulus (7,0 N and 231,7 MPa) when compared with the starch films (1,4%; 18,6 N; 1772 MPa and 3,2 ?0,01 x 10 -10 g.m/m2.h.Pa respectively). From SEM analysis it was observed that the flour films have flaws in its surface and a cross section less dense, with small cracks compared with the starch films. FTIR spectra showed presence of OH groups, CH2 and amide III in both films, while the amide group I was only observed in flour film. Optical properties showed that the flour films were yellowish while the starch films were clearer and less opaque

ASSUNTO(S)

biofilme film amido canna indica l flour starch farinhas

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