Monitoramento do desempenho do processo de secagem por atomização e caracterização físico-química do leite desnatado na aplicação de um protocolo de encapsulamento baseado em modificações de pH

Abstract

Spray drying is a process widely applied in the dairy industry to produce powder ingredients, mainly as powder milk and its derivates. In this document drying technology is addressed in two different projects. For the first project, it is relevant to consider that in the industrial scale the modern drying equipment presents two and three stages for the evaporation process, nevertheless in the pilot scale it is common to dry using single-stage spray dryers. In this project a characterization of the performance of a pilot scale single-stage spray dryer was performed in terms of the experimental parameters. The studied parameters were mass and energy balance, while the independent variables were inlet drying air temperature, inlet product flow rate, and nozzle selection. The results suggest that the inlet product flow rate improves the performance because it increases the nozzle pressure, which enhances the surface area of the droplets for increasing the mass and energy transference in the drying process. The nozzle selection can significantly affect the performance of the spray dryer, so it is important to guarantee the non-utilization of pieces with defects. The effect of inlet air temperature was to increase the lost energy in the process and did not improve the performance, suggesting that the equipment needs to optimize energy utilization by isolating the drying chamber. For the second project was addressed an encapsulation technology for fat-soluble vitamins which could be applied in the production of fortified skimmed powder milk. The objective was to evaluate the effect of the total solid concentration and characterize the physicochemical interactions in the system through the application of the encapsulation protocol; the protocol was divided in three treatments. The studied parameters were electrophoretic mobilities reported as surface zeta potential, conductivity, particle size distribution, and soluble ionic calcium; while the independent variables were total solid concentration and treatment applied. The main results are that the protocol can be applied with a total solid concentration of 17 g.100 g-1 and reversibility of the expansion-contraction process of the casein micelle is inversely proportional to the concentration of the product