Avaliação dos efeitos da radiação gama em blendas de hidrocoloide da chia/pectina de maçã

Abstract

The aim of this work was to evaluate the effects of different doses of γ radiation on the thermal and morphological properties of polymer blends obtained from apple pectin and chia hydrocolloid (Salvia hispanica L), rich in carbohydrates, proteins, lipids and with great capacity antioxidant, with the inclusion of glycerol and glutaraldehyde as additives in order to observe the formation of hydrogels for such blends. Four formulations that presented satisfactory results in preliminary tests, with respect to the mechanical responses of modulus and tenacity, were selected. The formulation of the blends studied had the following mass composition (pectin/hydrocolloid/glycerol/glutaraldehyde): (I) 34/21/25/20; (II) 41/29/25/5; (III) 41/14/25/20 and (IV) 35/35/25/5, respectively. These suspension blends were subjected to radiation doses of 2.5, 5.0, 7.5 and 15.0 kGy. The production of the blends was carried out through the casting methodology. The results showed that blends I and III suffered greater degradation observed by the results obtained with FTIR/ATR and DSC analysis. The FTIR / ATR spectra presented variations in bands associated with the deformation of –OH and C–O–C groups, increasing the absorption intensity of the hydroxyl groups and decreasing the ether bond strengths as the radiation dose increases, observing the increase of the absorption intensities ratio –OH and C–O–C in blends I, II and III. The thermal analysis results (DSC) of the blends showed a main endothermic event attributed to the water outlet around 100 ºC, which was not observed in the second scan for all samples. The formation of agglomerates in the form of sticks observed under an optical microscope was also observed. These results indicated that the radiation was effective in the degradation of the polymeric structures and not in the increase of crosslinking as expected, leading to the conclusion that the formulations selected to make the blends are not suitable for obtaining hydrogels.