Effects of ultrasound treatment in the process formation of zein edible films (107)
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The Ultrasound treatment is an emergent technology with a nonthermal physical process that has several applications in the food industry. Ultrasound application could improve the polymer matriz homogenization and produce films with good properties for the packaging industry. The power and time applied during the treatment affect the film properties because they have direct influence in the protein structure. In this work films with ultrasound application at 120 W, 400 W and mechanical agitation at 650 rpm for 5 and 10 minutes were made. Then, some important properties, such as film thickness, transparency/opacity, solubility, swelling studies and optical microscopy images were analyzed. The thickness can be affect by various process and influences other properties, the ultrasound treatment of 120 W in 5 minutes showed one of the lowest thickness of the films. Transparency/opacity were slight higher in the film with ultrasound treatment for 5 minutes, probably due to the better dispersion of oleic acid in the matrix. Water solubility and swelling index had no significant (<0,05) differences in the films, presenting similar water properties. Optical Microscopy showed a difference in the ultrasound micrographs: when the intensity and time of ultrasound treatment increase; a raise in the size of the white spots in the microstructure can be observed. Further studies in the microstructure and the effect of higher intensities of ultrasound is necessary.