Liofilização de alimentos com forma esferoidal: experimentação, modelagem e simulação.

Abstract

The production of foodstuffs has increased with each passing year and unfortunately so has the waste. In this way, the optimized studies of the processes are thus increasingly for the conservation, the optimization and the optimization and the processes more and more efficient. Seeking to improve the freeze-drying process of fruits, this work presents a numerical and experimental study on the freeze-drying process of tropical fruits. It was necessary to determine which coordinate system best describes the geometry of tropical fruits, using the epheroid system of combinations. A transient two-dimensional thermophysical model was developed in each of the lyophilization phases to predict the heat transfer, considering the symmetry around the center of the solid, constant properties and volume. The connection boundary solution was calculated via the volume numerical method, considering a convection condition on the solid surface. To validate the numerical methodology, freeze-drying experiments were carried out with bananas of the Musa paradisiaca variety. The fruits were frozen with freezing at temperatures of -51, -33, -28 and -27 °C, and drying in a freezing chamber whose pressure in the freezing chamber was less than 1 mbar. Experimental results of kinetics and fruits were shown and analyzed. It was found that the temperature gain and loss curves of the fruits were influenced by the freeze-drying phase. Theoretical results of fruit temperature were obtained from the experimental results, allowing the determination of the convective heat download coefficients compared. A good fit was observed between the predicted and experimental results