Desidratação parcial de tomate cereja em secador de bandejas vibradas com reciclo

Abstract

In this essay, it has been analyzed the partial dehydration of oval cherry tomato Lycopersicum sp. Mill, by using a vibrated tray dryer with recycle until the tomatoes reached 15% of its initial water content what represents 70,19% of humidity in wet basis or 2,35 kg of water/kg of dry mass in dry basis. The dryer used consists basically of a vertical dryer tunnel with four perforated trays by whose perforations tomatoes and air flow where drained in a crossed way, being the latter injected at the bottom of a pipe connected to a blower, allowing the adjustment of output and also to go through a series of four resistors that sets the temperature. All trays are connected to a vibration system that helps the tomatoes flow, which are recirculated with the aid of a conveyor belt. CCD was used to verify the influence of significant variables of the process: air flow, temperature and tomatoes mass. The analyzed response was the amount of in natura tomatoes processed in a day. The optimum operating condition was experimentally reproduced, validating the results obtained in the CCD, where there was obtained 18, 729 kg of tomatoes processed per day, with an optimum temperature of 67.6 ° C, airflow rate 6 kg / min and amount of processed tomatoes of 4.025 kg. In the optimum condition of the dryer it has been studied the drying curve and drying kinetics. The drying process started with the dryer working in batch without tomatoes recicle, until achieve the moisture content of 85% approximately, followed by the addition of porcelain spheres with a diameter of 0.0235 m, that forced the tomatoes particles flow and the process began to occur with recirculation. In the drying knetics, three periods were identified: two periods that the dried tomatoes in steady state rates, interspersed with a variable rate period. For the drying rates constants, quantified values of the correlation coefficient above 0.99, linear fitting a straight line with the experimental points. Comparing the behavior of the fixed bed with the vibrated bed, it was observed that the application of vibration acted in decreasing by 30% the drying time. The results indicated that the simultaneous influence of vibration and porcelain balls intensify the drying process, resulting in a peculiar air drying.